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Is Nature Unnatural?
June 1, 2013 10:20 PM   Subscribe

Decades of confounding experiments have physicists considering a startling possibility: The universe might not make sense. For you Saturday night science read, a very interesting science article, one of many on the Simons Foundation web site
posted by Long Way To Go (84 comments total) 45 users marked this as a favorite

 
There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory, which states that this has already happened.
posted by Confess, Fletch at 10:34 PM on June 1, 2013 [49 favorites]


Yep, Douglas Adams trumps Albert Einstein...
posted by oneswellfoop at 10:35 PM on June 1, 2013


Is Nature Unnatural?

No.

Now, to go read the article itself.
posted by benito.strauss at 10:46 PM on June 1, 2013 [7 favorites]


Not having read the article yet, I’m pretty sure the premise that it doesn’t make sense is wrong. From my time at MetaFilter I’ve learned that there are many people who have it all figured out.
posted by bongo_x at 10:51 PM on June 1, 2013 [18 favorites]


“Ten or 20 years ago, I was a firm believer in naturalness,” said Nathan Seiberg, a theoretical physicist at the Institute,

You mean you were a firm believer in the naturalness you thought you had a grip on. It turns out the lens you were looking through showed only a cross-section of what was going on and now you'd rather pursue the idea of non-naturalness then to retrain yourself and build the new lens that accounts for the new information.

The Higgs Boson results are brand spanking new by physics research standards. Perhaps we should ponder them a while before throwing up our hands and claiming defeat.
posted by Tell Me No Lies at 10:55 PM on June 1, 2013 [17 favorites]


Well, the universe might not make sense, but I know there's always a lighthouse.
posted by laconic skeuomorph at 10:59 PM on June 1, 2013 [1 favorite]


Without my having to read through an article by a potential nutbar can I have a hint about what we're talking about? What in physics are we talking about here?

Having a title where all I know about the article is that they confuse definitions doesn't give me a lot of faith in the article or the poster.
posted by ishrinkmajeans at 10:59 PM on June 1, 2013 [2 favorites]


“We don’t have an understanding of a basic extraordinary fact about our universe,” he said. “It is big and has big things in it.”

'kay. Thanks Dr. Arkani-Hamed, about the grant money...?
posted by Smedleyman at 11:04 PM on June 1, 2013 [3 favorites]


ishrinkmajeans, my summary (with limited knowledge of the subject): our theories have been wildly successful for most of the things we've tested. But there are a couple troubling points (Higgs, vacuum energy) that not only don't agree with predictions, they're hundreds of orders of magnitudes off.

So is it possible that some things in the universe don't (and won't) fit neatly into theories? Multiverse theory suggests that there are just so many universes out there, it's statistically probable that some will work even though a couple constants are wildly unpredictable (other things cancel them out).
posted by sbutler at 11:06 PM on June 1, 2013 [1 favorite]


" Perhaps we should ponder them a while before throwing up our hands and claiming defeat."

When it comes to physics, I threw up my hands and claimed defeat in tenth grade. THAT SHIP HAS SAILED.
posted by Eyebrows McGee at 11:28 PM on June 1, 2013 [17 favorites]


(And it sailed under some totally incomprehensible form of motive power beyond the minds of men, obviously.)
posted by Eyebrows McGee at 11:29 PM on June 1, 2013 [19 favorites]


can I have a hint about what we're talking about? What in physics are we talking about here?

IANAP, but there's a general premise on which a lot of physicists operate, that the universe is "natural", which means (according to Einstein) that the laws of physics that undergird the universe are "sublimely beautiful, inevitable and self-contained". In other words, like Maxwell's equations, underlying very complex physical phenomena, there's a lovely equation from which it all spins out, and the mission of science is to find that equation. This motivates a lot of physicists, apparently, because that premise entails that there's an achievable goal.

Against that, you have String Theorists saying there is no final equation, there's just a near-endless series of multiverses, and the particular universe in which we find ourselves has a set of constants that are key to the particular shape of our universe, but they're totally random and accidental, just a lucky roll of the dice that happened to create a universe that eventually birthed creatures capable of asking the questions we're asking. This is dis-spiriting to a lot of physicists because, in part, it means that the universe really can't be understood in any deep sense. You can measure a bunch of things, but the answer to the question "why does that cosmological constant have that particular value?" is just "it happens to be that way where we are."
posted by fatbird at 11:31 PM on June 1, 2013 [20 favorites]


Ok, so the options are that the universe does not "make sense" in a way we can comprehend which is where the New Mysterians stand, that it does make sense but not in a way we yet fully understand which is what we call "science", or it does make sense but that that sense is mutable.
posted by fallingbadgers at 11:32 PM on June 1, 2013 [2 favorites]


Imagine that baking was an incredibly opaque topic, that the average person has no direct experience with. People have seen bread in movies, and they vaguely know that into the bakery goes a bunch of things, but something altogether different comes out.

Now imagine you are a writer and you have to write an article about a new kind of bread bakers are making, with a no-knead dough, and how that might change the industry in profound ways.

Except it has to be 1000 words long. So forget explaining at the chemical level, how proteins change shape etc.--you don't even have the space to explain that flour comes from milled grain. Doesn't matter; your audience hasn't ever seen a loaf of bread in person, much less thought about how it is made.

So for half your article you're explaining what bread IS, what it tastes like and what normal bread is like to someone who has never had a slice. Any maybe you allude to it being from plants, but it's left unexplained how something green tough and fibrous can also be light and airy. But you're not actually explaining at all, you're kind of just using a bunch of metaphors from completely unrelated experiences. "Well a loaf of bread is kind of squishy, like a car tire. And it initially comes in a form that isn't a solid but isn't a liquid, to which we add fire, but it doesn't burn. Oh and if you leave it out for a day it turns into a rock."

And then you're explaining this new no-knead dough and how now bakers (whatever those are) are going to be able to make a lot more loaves (whatever that is) because they don't have to spend hours kneading (???) anymore.
posted by danny the boy at 11:32 PM on June 1, 2013 [47 favorites]


The article is saying that the calculated mass of the Higgs boson (after interactions with other particles increase its mass) is 10 000 000 000 000 000 000 giga-electron-volts greater than the value observed in experiments at the Large Hadron Collider. Furthermore, if the Higgs was only five times heavier than the measured value (never mind 10 000 000 000 000 000 000), life couldn't exist in the universe.

So either theory is wrong somehow, or the "bare mass" starting value of the Higgs is so negative it cancels out the tremendous increase added to it by other particles and the result is the very convenient measured value of 126 giga-electron-volts that makes our universe possible. It could have been anything, but it turned out to be within that extremely precise range.

Then the article talks about how the vacuum energy is a trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion times smaller than theory says it should be. This is a different area of physics (not directly connected to the Higgs Boson), but the result is the same: a fundamental constant that could be anything from here to umpty zillion happens to be within a very narrow range that allows the universe to exist.

Given what we know, it's something of a puzzle that the universe exists at all. It's like dumping a box of broken marble shards on the ground and spontaneously getting a Venus de Milo statue: a highly improbable series of coincidences with an even more unlikely result. This is why the article suggests that there are a great many universes and we happen to inhabit the one with the constants at the necessary values.
posted by Kevin Street at 11:35 PM on June 1, 2013 [9 favorites]


Well, that's just great, now we realize this, now, after all this time, we only realize this now, now all too late, by now our universe is way beyond warranty. Way to go scientists, way to go.
posted by TwelveTwo at 11:43 PM on June 1, 2013


"...In other words, like Maxwell's equations, underlying very complex physical phenomena, there's a lovely equation from which it all spins out, and the mission of science is to find that equation. This motivates a lot of physicists, apparently, because that premise entails that there's an achievable goal."

Well said. I think one reason physicists believe so strongly in naturalness is because mathematics works so incredibly well in quantifying physical law. And math is a single, tremendously complex system of thought. All of math fits together, so why shouldn't the universe work the same way?

We've gone from believing that the universe is a giant clockwork mechanism to believing that it's an enormously complicated mathematical equation, or computer program. Press "run" and the universe happens.
posted by Kevin Street at 11:49 PM on June 1, 2013 [2 favorites]


Of course it's within the narrow range necessary for the universe to exist. The universe does exist. Doesn't it?

Anthropic argument much?
posted by I-Write-Essays at 11:53 PM on June 1, 2013 [17 favorites]


That the universe may not really make a whole lot of sense to the people who study it professionally makes me feel slightly better about the occasional lack of analytic traction on questions that interest me.
posted by clockzero at 11:59 PM on June 1, 2013 [2 favorites]


I'm always excited when the physicists have to reevaluate their basic model. I keep hoping that one of these times someone will come up with an explanation for the double slit experiment that actually makes sense.
posted by Tell Me No Lies at 12:11 AM on June 2, 2013


Given what we know, it's something of a puzzle that the universe exists at all. It's like dumping a box of broken marble shards on the ground and spontaneously getting a Venus de Milo statue: a highly improbable series of coincidences with an even more unlikely result. This is why the article suggests that there are a great many universes and we happen to inhabit the one with the constants at the necessary values.

Yeah, I think that's all total nonsense and a product of crappy pop science journalism.

It's revealing that they're talking about Einstein and naturalism because Einstein famously said that he knew the General Relativity must be true because it's so beautiful while, in contrast, he hated quantum mechanics because it's so ugly. That's a mystical (or quasi-mystical anthropocentric) view of the natural world and it's bunk. I love Einstein, but it's bunk.

The truth is that the entire history of science is of deeper complexification and a movement away from human intuition.

The framing of this article is all about philosophy of science, not science, and as philosophy of science, it's shit.

To wit:

"Anthropic argument much?"

Right. The discussion is circling around the anthropic principle without even mentioning it. And the anthropic principle is either crap (strong version) or trivial and uninteresting (weak version).

Now, having said that, what these actual physicists are actually discussing is important because, without resorting to going so deep as to talk about the anthropic principle and a necessity of multiverses and such, it does make sense to care about theoretical elegance and parsimony.
posted by Ivan Fyodorovich at 12:13 AM on June 2, 2013 [5 favorites]


Not that any of it matters since with virtually 100% certainty our own galaxy or something more local will stomp us out like ants long before we develop any survival technology with more than a remote chance of success.
posted by Ardiril at 12:14 AM on June 2, 2013


Or, you know, to quote Haldane "Not only is the universe queerer than we suppose, it's queerer than we CAN suppose."
posted by symbioid at 12:23 AM on June 2, 2013 [4 favorites]


Well said. I think one reason physicists believe so strongly in naturalness is because mathematics works so incredibly well in quantifying physical law. And math is a single, tremendously complex system of thought. All of math fits together, so why shouldn't the universe work the same way?

It would do physicists a great deal of good to spend some time with biologists, some time. Hell, even chemists might teach them something.
posted by Jimbob at 12:37 AM on June 2, 2013 [3 favorites]


You lie down with dogs, you get fleas. If your world view commits you to weird metaphysical entities like "natural laws" then you can't be too surprised when they get, well, weird.
posted by thelonius at 12:39 AM on June 2, 2013


“Particle physicists, especially string theorists, had this dream of predicting uniquely all the constants of nature,” Bousso explained. “Everything would just come out of math and pi and twos. And we came in and said, ‘Look, it’s not going to happen, and there’s a reason it’s not going to happen. We’re thinking about this in totally the wrong way.’ ”

This is the important quote. If everything could be derived from math, then we could pat ourselves on the back and say that we finally understood everything. But if the fundamental constants are not uniquely determined, but instead the product of some cosmic dice roll for our universe, then there will be a kernel of knowledge that will forever elude our grasp.
posted by Pyry at 12:47 AM on June 2, 2013 [3 favorites]


Of COURSE it doesn't make sense. That's why we're dancing.
posted by BitterOldPunk at 1:10 AM on June 2, 2013 [12 favorites]


So we're saying that there's more than just earth, air, fire, and water? They make such a beautiful tetrad that it's hard to believe that the cosmos could be ruled by anything else, but I suppose needs must.
posted by benito.strauss at 1:25 AM on June 2, 2013 [2 favorites]


To me, it is just plain stupid to continue operation of mechanisms like the LHC at still higher energies and uncertainties than those at which it has previously been operated, in our own biosphere, when we don't understand and have fully integrated into our overall science the results of previous runs. It shouldn't run again, until we're all OK with the poorly understood results of its last run.

I think it's basic to human survival that, as the energies and results of physics experiments increase into the more and more improbable, that the distance at which such experimentation occurs, relative to the domiciles of most of humanity, increase at least at square power law rates. Because when, not if, something fundamental goes wrong, being commuting distance from home is going to seem pretty stupid to pretty much everyone but the principal investigators.
posted by paulsc at 1:25 AM on June 2, 2013 [2 favorites]


The article seemed more fixated on the question: "Is Nature Unnatural?" And this produced a very loose and uninteresting article. But I think a much better ground article could have been made on the subtitle: "The universe [may] not make sense."

J.S. Bell (of Bell's Theorem) published a collection of essays where he at one point quotes from several past physicists concerning the nature of physics in light of quantum mechanics:

"Bohr once declares when asked whether the quantum mechanical algorithm could be considered as somehow mirroring an underlying quantum reality: `There is no quantum world. There is only an abstract quantum mechanical description. It is wrong to think that the task of physics is to found out how Nature is. Physics concerns what we can say about Nature' ".

The point is that with the introduction of quantum mechanics, several phenomena were introduced which, as far as we can tell at this point, seem to operate without any underlying physical substrate. That is to say, there's nothing further out there for us to probe. There are effects without any underlying empirical cause. And this is something that science (and humanity) may have to accept at some point.

Classical mechanics provides us with causal accounts: Why did the billiard ball A move? Because billiard ball B struck it.

Quantum mechanics cannot: Why did the alpha particle break past its barrier? Well... there's simply no causal account which we will ever be able to give, because there is none.
posted by SollosQ at 1:31 AM on June 2, 2013 [2 favorites]


But quantum mechanics can give a mathematical description of how certain events happen, even when "common sense" or purely physical descriptions break down. It's an astounding triumph of theory that was later confirmed by experiment. Because of that I think Bohr would probably be a very strong advocate of naturalness - the idea that all of nature can be derived from equations.
posted by Kevin Street at 1:44 AM on June 2, 2013 [1 favorite]


The first paragraph:

"On an overcast afternoon in late April, physics professors and students crowded into a wood-paneled lecture hall... With his dark, shoulder-length hair shoved behind his ears..."

Powerful stuff. I'm hooked.
posted by EnterTheStory at 2:01 AM on June 2, 2013


Physicists are so excitable: always telling us either that they're on the brink of understanding everything, or that nobody understands anything.
posted by Segundus at 2:46 AM on June 2, 2013 [6 favorites]


I can't quite put my finger on what is in this article that evokes the smell of woo.
posted by Blazecock Pileon at 3:16 AM on June 2, 2013


Physicists reason that if the universe is unnatural, with extremely unlikely fundamental constants that make life possible, then an enormous number of universes must exist for our improbable case to have been realized.

The whole argument that oh how unlikely and remarkable is our birth so therefore multiverse (or any other pet theory of the author) always annoys me as it confuses cause and effect in such a fundamental way. It's not that the universe had to be a specific way for us to exist, it's that we exist because the universe is a specific way. Musing about how very special our universe has to be give rise to us is just another way for humans to feel special now religion doesn't quite cut it anymore.
posted by MartinWisse at 3:37 AM on June 2, 2013 [4 favorites]


However, in order for the Higgs boson to make sense with the mass (or equivalent energy) it was determined to have, the LHC needed to find a swarm of other particles, too. None turned up.

Reading things like this about the standard model and supersymmetry always makes me wonder if they're not just the modern version of epicycles. We can always add an nth order correction to the equations to make them a bit more accurate, but somewhere we've missed a flawed assumption, and when our Copernicus/Brahe/Kepler folks arrive, there will be a sea change in our models.

I hope I'm around for it.
posted by solotoro at 3:58 AM on June 2, 2013 [9 favorites]


MartinWisse: It's not that the universe had to be a specific way for us to exist, it's that we exist because the universe is a specific way.

I don't think the argument is that Nature "conspired" or "willed" the laws to enable us to exist, but that of all the conceivable permutations our Universe could have "adopted", only the specific permutation that it did would have accommodated life. From that jumping off point, the quote you included is the natural response for someone who favors a world with no supernatural intervention.

And I think the obvious rebuttal is that scientists can't be too sure of what exactly is required for life, and how improbable those circumstances are.
posted by Gyan at 4:16 AM on June 2, 2013


Also, it may be obvious that no other universe would suffice for our kind of life, but that doesn't mean no kind of life could arise in other universes.

But mostly, wondering about why the universe is exactly right for our kind of life is thinking that this is something that needs to be explained, rather than just something that is. I find it on a par of thinking of evolution as a process intended to produce us, rather than us just being a byproduct of evolutionary processes.

Does that make sense?
posted by MartinWisse at 4:51 AM on June 2, 2013 [6 favorites]


PhysicistsReporters are so excitable: always telling us either that they're on the brink of understanding everything, or that nobody understands anything.
FTFY
posted by CheeseDigestsAll at 4:58 AM on June 2, 2013 [5 favorites]


MartinWisse: that doesn't mean no kind of life could arise in other universes.

I concur with your sentiment but that is exactly what the anthropic thinking is suggesting i.e. any kind of life is only possible in our universe.
posted by Gyan at 5:01 AM on June 2, 2013


Man this thread is a mess. Can you guys actually read the article and maybe read the Wikipedia article on naturalness before commenting?
posted by empath at 5:02 AM on June 2, 2013 [1 favorite]


Einy rather famously said God doesn't throw dice.

What is pissing people off is that some facts, as we now understand them, support the notion that He did.
posted by seanmpuckett at 5:09 AM on June 2, 2013


A much better way to frame the problem would be to say that scientists long for a universe with no magic numbers. The sentence "Everything would just come out of math and pi and twos" nails it. Ever since the late 19th century it's been about showing that seemingly arbitrary constants emerge from the inevitable interaction of simple and inevitable components.

The thing is, while that idea is very elegant and has had a good run, it's also essentially a religious belief and the Universe is not ultimately constrained by our ideas of beauty. Like the world itself the Universe might be beautiful in certain ways only at a certain scale, and what the disappointed physicists in the article are worried about is that they have found the edge of the range across which their standard of beauty applies.

That leaves us as the one life-sustaining bubble in a mostly sterile foam of random universes, or having been tweaked either consciously or by some other mechanism toward a set of magic numbers that make us possible, and neither of those ideas is as appealing as our being mathematically inevitable.
posted by localroger at 6:38 AM on June 2, 2013 [6 favorites]


Gyan, I believe anthropic thinking focuses on conscious life, e.g. things that can actually consider and question the universe itself. It doesn't say that a universe couldn't exist that didn't allow for a slime to grow on a rock.

It's one of those ideas that is so simple- we can think about the universe, because the universe it compatible with our form of life.

It's like standing next to the reject pile outside a toy factory, there's no inherent special design in each broken toy, they're just dice rolls, but some, one out of a million, might be just good enough to be loved by a kid, so you give it to a kid, and it is loved.

You could say, looking at the kid with the toy, "Ahh! This toy is compatible with the love this kid gives it" but saying that doesn't mean there are others that couldn't also be loved, maybe for a day, maybe for a lifetime, maybe by a dog.

Now, you, having seen these million reject toys, could easily say "Aha, with all these data points, I can probably deduce the single rule that created them all" and you would, with a bit of thought, be able to actually sketch out a fairly sensible idea for the machinery that created them, and the variables of each part. "The ear stitching stage can error between 2 and 7 stitches and 0.01% of the time it even lacks thread".

What science is trying to do is deduce the machinery, but only after being given the single toy that was loved. Can it even be even roughly deduced without knowing about the size and shape of other universes, that's the question.
posted by Static Vagabond at 6:43 AM on June 2, 2013 [1 favorite]


It doesn't say that a universe couldn't exist that didn't allow for a slime to grow on a rock.

To be clear, the problems with "sterile universes that do not support life" go far beyond supporting slime but not humans. They are mostly universes where stars might not be stable, or where chemistry might not be possilbe because atoms can't bind together electrically, or where atoms more complex than hydrogen might not be possible. Only a vanishingly small number of those 10500 possible universes are likely to be enough like ours to even worry about small changes to the chemical properties of carbon.
posted by localroger at 6:48 AM on June 2, 2013 [5 favorites]


I haven't read anything that discounts the anthropic principle outright. It's kinda immutable. We're here because the physics of our solar system permit it. There's no god, there is, however, the fact that we exist. And for us to exist we need a universe that's receptive. Love you all!
posted by panaceanot at 6:49 AM on June 2, 2013 [1 favorite]


I dunno, I read these kinds of articles and it's as if God is winking.
posted by St. Alia of the Bunnies at 7:01 AM on June 2, 2013


Man, that God has his finger in a lot of pies!
posted by sneebler at 7:02 AM on June 2, 2013


Static Vagabond: I believe anthropic thinking focuses on conscious life, e.g. things that can actually consider and question the universe itself.

As per physicalism, a conscious brain is just a complex physical entity. No magic physics sauce needed relative to the slime apart from some time (a few billion years, tops) and some accommodating weather and neighbors.

Like localroger said, the anhropic principle is about an universe favorable to the chemistry of life (which would include slimes as well)
posted by Gyan at 7:11 AM on June 2, 2013


"Parallel universes cannot be tested for..."

Just got to this line in the article and went "Wait, why not?" Seems like the natural next step. Figure it out science peeps! I'll be over here making bad puns about it while you do.
posted by Potomac Avenue at 7:13 AM on June 2, 2013



Things like this make me wish that I taken the pure science route in higher education rather then what I chose. I want to understand it more then I do.

I wonder if it's too late to become a theoretical physicist.
posted by Jalliah at 7:15 AM on June 2, 2013 [1 favorite]


tl;dr: there is no tl;dr
posted by klarck at 7:19 AM on June 2, 2013 [2 favorites]


Things like this make me wish that I taken the pure science route in higher education rather then what I chose. I want to understand it more then I do.

I wonder if it's too late to become a theoretical physicist.


I think the same way sometimes, and then I remember how much math is involved.
posted by Foosnark at 7:22 AM on June 2, 2013 [1 favorite]


It is pretty apparent to me that randomness is the god that fills the gaps for materialists.
posted by vorpal bunny at 9:08 AM on June 2, 2013 [1 favorite]


Apparently, it’s physics-week here on metafilter. I’m awake, I’ve got my coffee, let’s get physical.

What this article is discussing is the technical concept of “Naturalness.” Naturalness does not mean “pretty theories” or “mathematical elegance.” What the Naturalness problem is attempting to tackle is why are there vastly divergent energy scales* in the physical laws that govern the Universe?

*As I’ve discussed in detail before on metafilter, you can convert any other dimensionful quantity (length, time, mass, volume, etc) into some combination of units of energy by use of the Planck constant. I will use the energy unit I am most familiar with, the giga-electron volt (GeV) here. A proton is about 1 GeV (it’s 0.938 GeV), an electron is 0.511 MeV (so 5.11 10^-4 GeV). The top quark is 174 GeV and the Higgs we have just discovered is 125.5 +/- 1 GeV. A photon of visible light is around an eV of energy (1 billion times less than a GeV), xrays are keV-MeV-ish, and gamma rays are MeV+. A GeV is 1.6 10^-10 Joules, and to convert to time or length units, an inverse GeV is about 2 10^-16 meters or 6.6 10^-25 seconds. So when I speak on different energy scales, you can think of this question as “why are there different lengths over which physics is different?” or “why are there different time-scales that are important?” It’s all energy, maaaaaan.

So, when we look at gravitation (general relativity, GR) and quantum field theory (quantum mechanics crossed with special relativity, QFT). We famously know that the two theories don’t play well together. However, we can still make some predictions with reasonable confidence (Hawking radiation for example). One of these is a prediction of at what energy everything goes to shit: when does it become clear that GR and QFT by themselves are just totally off the rails? it’s a pretty interesting and important fact that these theories contain the seeds of their own destruction, meaning that these theories cannot be good to all regimes, they must be modified somehow. String theory is an attempt to find that necessary modification, but I’m not a string theorist, so moving right along.

The highest possible scale when things must get nuts is the Planck scale. Think of it as the scale at which a quantum particle would have too high of an energy density to avoid becoming a black hole. This Planck scale is given by the Planck mass, or 1.2 10^19 GeV (there are also Planck lengths, the smallest length we can imagine in QFT, Planck times, the shortest time something can be said to exist, but I stick with energy). OK, the Universe might become non-QFT-like below a Planck scale, but if you can get your QFT theory to behave nicely up to the Planck mass, you’re set and you never have to worry about it falling apart in a regime where you thought it shouldn’t.

Now, waaaaaaaaaay down here, 19 orders of magnitude below the Planck scale, we have all these nice little protons and neutrons and quarks and electrons and so forth. These are well-described by perfectly reasonable quantum field theories, that include, quite literally, the most accurate theory of anything ever developed in science (quantum electro-dynamics, describing the interactions through the electromagnetic force, and why Gell-Mann and Feynman won their Nobels for).

The basis of QFTs is something called the “action.” The action is a strange thing; its a combination of terms representing the kinetic and potential energies for fields, and it’s hard to describe in a way that will make sense without any other context, unfortunately. However - and this is very important for those of you who think quantum mechanics is divorced from Newtonian mechanics - the action is what controls macro-scale physics. The motion of classical particles is governed by the action: every particle follows a path that extremizes the action (minimizes or maximizes the action). This is the classical path of a particle, and gives you Newton’s Laws of motion. The difference between quantum and classical motion is that a quantum particle in some sense “feels out” the other paths that are not the extremes, and there’s some sense in which it “travels along” all of them, which can allow for interference. Classical physics is the anomaly, not quantum physics: we just lumber around at scales too big to see the deviations from extreme action that really govern the Universe.

OK, so there’s an action, which is an integral over space-time of something called the Lagrangian (I just keep introducing words, don’t I? Bear with me). For quantum fields, the Lagrangian contains terms that are describe both the motion of the field (kinetic terms), and terms that describe the interaction of the fields with themselves and other fields (interaction terms). One of these interaction terms is a “mass term,” and this is where the trouble will come for the Higgs.

When you work with a QFT, each of these terms in the Lagrangian can get “corrected,” by high energy effects of other particles. The term here is “renormalization group evolution.” Say you care about the mass term. The mass term in the Lagrangian ties two instances of the field together: particle comes in, particle goes out, mass term tells you how much energy that particle needs to have to exist. Now, imagine that you also have a term in the Lagrangian that connects two instances of the particle with two instances of another type of particle that’s very very very heavy. If you probe the lighter particle in more detail (at smaller scales, and thus higher energies), you’ll see that, in addition to the mass term you thought was there (which I’ll call the “bare mass”), what you thought was the mass term also includes this 4-particle interaction: your light particle came in, spun-off a massive particle, which ran around in a loop and got eaten back up by the light particle, which went off on it’s merry way.

That crazy little loop will change the mass of the light particle. The amount of energy needed for the particle to exist at rest (the very definition of mass) is now different from the bare mass because of the loop, and it’s dependent on some much higher energy scale (the mass of the heavy particle involved). We call the measured mass the “physical mass,” and it’s now the sum of the bare mass and loop-correction. This happens for everything in the Lagrangian. Coupling constants physically change with energy: electromagnetism gets STRONGER as we move to higher energies (and coincidentally, the other two forces that govern QFTs: weak and strong nuclear forces, evolve to meet the electromagnetic force, appearing to unify at 10^15-10^16 GeV, but that’s another story). Renormalization group evolution sounds crazy, but we’ve measured it’s effects.

For spin-1/2 particles (called fermions) like an electron, the renormalization of the bare mass is logarithmic. That means that, as you look at higher and higher energies, the physical mass is given by
(some number)*bare mass *log (energy scale/bare mass).
Due to the presence of the logarithm, even if nothing interesting happened up to the Planck scale, the physical mass of the electron (for example) would only be 10% different from the bare mass. So there’s no worry about “why the electron is light?” It’s light because the bare mass is small, and renormalization won’t change that (why the bare mass is small is another question, but that’s not part of Naturalness). Also note that if the electron bare mass was zero, it would stay zero, because there’s a symmetry of Nature that protects it.

Now, for spin-0 scalars like the Higgs boson (the word “boson” actually means spin-0 or spin-1, and the Higgs has to be spin-0), the correction to the mass goes like
mass^2 = bare mass^2 + (some number)*energy scale^2.
Without a logarithm.

That’s the Naturalness problem. We know that the physical mass is 125 GeV (and even before discovery, we knew that it was below about 2000 GeV). We don’t know where the next scale of physics lies (the scale at which our theory changes and we have to start calculating renormalization flow differently), but let’s say that it’s the Planck scale (meaning nothing interesting happens between this energy scale and that). Then the physical mass is the sum of the bare mass plus a loop correction up to 10^19 GeV (squared). That’s the sum* of two numbers, one of which is 38 digits long, and the result is a 5 digit number (125^2 GeV^2 =15625 GeV^2).

*the loop corrections can be negative, so they can cancel.

Imagine I ask two of you to pick 38 digit numbers. Ignoring the fact that its hard for humans to pick truly random numbers, if I took those two numbers and subtracted them, how many digits will the result be? There’s a 9/10 chance it will be 38 digits long, 1/10 it’s 37, 1/100 it’s 36, and so on. To get two numbers that don’t have any connection between them to cancel for 33 digits? Something’s up. That’s the Naturalness problem (related to the hierarchy problem, which is “why isn’t the weak scale - the scale of the Higgs physical mass - the same as the Planck scale?” but they are two sides of the same coin).

So we think that something must come in and fix it so that the bare mass and the loop correction are about the same size. Since the physical mass is 100 GeV-ish, we suspect this means that the bare mass is also that size, and the loops are prevented from getting too much larger than 100 GeV-ish (how much cancellation you’re willing to accept is called the degree of fine-tuning).

There are 3 “obvious” ways to fix this problem:

Cancel the loops. The loops for the Higgs are due to every particle that gets a mass from the Higgs mechanism: the W and Z bosons, the quarks, and the leptons. Introduce another set of particles that exactly cancels each loop in turn. This requires a symmetry between each particles and it’s new partner, forcing each new loop to be exactly the same size but have the opposite sign. Supersymmetry, which flips the spin-statistics of the particles (spin-0 becomes spin-1/2, spin-1/2 becomes spin-0, and spin-1 becomes spin-1/2) is the most famous example of this, as switching spin-statistics just puts a negative sign in front of the loop correction, so the particle and the superparticle exactly cancel. There are other, less “elegant” methods of canceling the loops. Nima Arkani-Hamed made his name coming up with several.

Since we know that there are no spin-0 electron partners at 0.511 MeV, we know that this symmetry cannot be perfect: supersymmetry, if it exists, is broken. This pushed the new particles up in mass, but not too heavy: the larger they are, the less perfectly the loops are canceled and so we reintroduce the Naturalness problem. The amount of fine-tuning you are willing to accept is a personal preference, most theorists know something is fine-tuned when they see it (so, you know, like the Supreme Court and porn). The lack of superpartners at the LHC yet is what’s driving this fear over naturalness; without quark-partners below a TeV, the required tuning is getting worse, and people are freaking out.

2) Make the Planck scale small. That is, bring the mountain to Mohammed. We don’t actually know the scale at which gravity gets strong is 10^19 GeV; that’s an extrapolation. Maybe it’s 1 TeV. To avoid violating the shit out of every measurement of gravity we’ve done, the way to do this is to introduce extra dimensions that are small. We can’t propagate in the extra dimension, but gravity can, and the fact that the gravitational force needs to expand out into those other directions is what makes us think gravity is weak here in our 4D space. Nima came up with one set of extra-dimensional theories (so-called large extra-dimensions, which are still small, but you know, larger than the other small dimension theories), and Lisa Randall and Raman Sundrum came up with another set called warped extra-dimensions. Both are disfavored by more recent results.

Make the Higgs not be a scalar. Well, the Higgs is definitely a scalar, but maybe it’s made up of fermions, like a proton is made up of quarks. You never hear about the Naturalness problem with the mass of a proton, because the proton mass is set by the scale at which the strong force become strong; only about 4% of the proton mass is due to the Higgs mechanism, the rest is due to the strong confining force. Remember the strong force evolves, due to the renormalization group I talked about before. It starts small at some high scale, and gets stronger and stronger at low energies. At some energy, the strength goes “to infinity,” it’s literally impossible to isolate quarks because the binding force is infinitely strong. This sets a new scale in the QFT, and the masses of the collection of non-isolated quarks (protons, neutrons, etc) only care about that energy. So the strong force mass scale is protected.

This was the first idea for the Higgs, because we knew Nature picked this solution once before. We call it technicolor (get it? it’s like the strong force, which is described by particles of different “colors” instead of different charged, but new and improved. Physicists are so witty), and we all wish it were true. However, if the Higgs were a composite object, there would be subtle differences in precision measurements made even before the LHC turned on, and with the first results from the LHC, technicolor is looking pretty much killed. Though some technicolor guys will tell you it’s just pining for the fjords while nailing a parrot up on a perch.

So that’s the situation: of the 3 solutions to the Naturalness problem, only one (loop cancellation) is not in seriously dire trouble, and that’s getting there as we rule out the presence of new particles at higher and higher masses. So, people who think deeply about these problems are concerned that one of our motivating principles: that the Universe is Natural in this technical sense, might not be remotely relevant. Maybe the Universe just doesn’t give a damn about how it cancels loops.


Tell Me No Lies: well, the issue is that we’ve had the predictions for the Higgs Boson’s properties for about 30 years. They’ve been worked out to fantastic accuracy (people have calculated them out to two loops in QFT, which is quite the pain in the ass). Our expectation was that the results from the LHC would be similar to the Standard Model Higgs, but not quite: the Higgs would be produced with slightly the wrong cross section, and decay into the different final states a slightly different percentage of the time (the “branching ratios” would be different). The issue is that we’ve not seen these deviations as of yet. Which is starting to get people mighty nervous.

Personally, I think it’s insane to get that concerned yet, as the measurements are still extremely crude from the perspective of theory (though of course a huge experimental triumph; but intrinsically, the LHC is a messy machine to make fine-grained measurements. You need an electron-positron collider for that, and Japan is starting the wheels turning to build the International Linear Collider).

sbutler: for the multiverse solution to make sense, you need to have an “anthropic reason” for the odd result we’re seeing in our little patch of the Multiverse. For dark energy, there is one: if the density of dark energy were much larger than it is observed to be, the Universe would have expanded so rapidly that no gravitationally bound structures would have formed: no clusters of galaxies, no galaxies, no gas clouds, no stars, no planets, and so no possible observers to exist and say “wow, dark energy is just as large as my theory predicts.” Basically, there’s a reason that we can’t see dark energy as the “natural” value.

Personally I hate this way of doing science, but unfortunately the numbers for dark energy are quite convincing, so I can’t just ignore it because I find it distasteful. It’s something you have to consider if you want to work on those kind of problems. However, there’s no convincing argument that no observer could evolve in a Universe with a much larger Higgs mass. So that’s problematic.

paulsc: there are cosmic rays hitting the Earth continually that produce higher energies than the LHC is capable of. If we were accidentally going to kill us all by turning on the LHC, the Universe would have done it already by now.

solotoro: I understand why people outside of theoretical physics think this stuff looks like epicycles, and as we continue to decorate supersymmetry to avoid experimental bounds, it can get there. But the basic idea is not epicyclical at all: there’s a straightforward space-time symmetry that people had introduced even before the Naturalness problem that solves the issue neatly. That space-time symmetry is supersymmetry. Maybe it’s not true, but it’s got a convincing argument as to why it could be true, and so deserved and deserves the theoretical attention; as do pretty much all the other solutions I mentioned.

Sorry if that sounds like an argument from authority. I’ll be happy to follow up in more detail if you are interested.

Jalliah: I think I’d have to say that the bad news is it’s very difficult to catch up to a degree that you could be doing cutting edge research once you’re out of college. I’m sorry, that’s just kind of the way it goes. I’s not impossible, and I don’t want to discourage people who are interested in science from learning it, but I couldn’t in good conscience tell anyone past a certain age to go into physics grad school with the goal of becoming an active researcher. Again, not that it’s impossible, but the odds are so stacked against it that it would likely end badly. Even people coming up on the “usual” path should all be sat down and told “the odds of getting a paying permanent job doing this are against you, if you have other things that will make you happy in life, do that.”

The good news is that I think there is a lot you can learn through your own study that would allow you to follow this kind of science without having to get it filtered through science journalists. Empath I know has been learning this on his own; look at some of the old physics threads that he and I commented in, I gave some recommendations, and I think he has done the same for other people. Again, happy to discuss it in more detail if you are interested.
posted by physicsmatt at 9:13 AM on June 2, 2013 [51 favorites]


oh, and Potomac Avenue, the parallel Universes under discussion in Multiverse theories are not somehow "sitting right next to us" accessible via the oscillation overthruster. They would be in the same space-time as us, just way way way over the visible horizon of the Universe. They therefore are not in causal contact with our patch of the Universe: the space between them and us has inflated in such a way that light just will never have enough time to travel between them. So no test is possible, because we can never, even in principle, reach them or see them.

Which, you know, sucks.
posted by physicsmatt at 9:26 AM on June 2, 2013 [14 favorites]


Love this stuff, which for me is one path away from solipsistic thinking.

On a small note, KevinStreet mentioned upthread that scientists are confronting the possibility our universe may exceed the math we use to describe it. I started to favorite that comment until I considered that the multiverse explanation (as put forth in the linked article) is itself the product of our maths.

Inadequate as (our) math may be to account for (our) this (i. e. the universe), alternate physical models (e.g. multiverse with our "this" being a very unlikely bubble among many unlikely bubbles vastly outnumbered by likely "sterile" bubbles) are still being construed in math (and some more or less touchy-feely philosophico-cosmology utterances).
posted by mistersquid at 9:58 AM on June 2, 2013


Maybe it’s not true, but it’s got a convincing argument as to why it could be true, and so deserved and deserves the theoretical attention

Oh, I certainly wasn't suggesting we should just give it all up for a bad job. I'm a big fan of the work you guys do. Keep on keepin' on, and thanks for taking the time to share here. One of my favorite things about MeFi is that we have people like you sharing their expertise. Cheers.
posted by solotoro at 10:17 AM on June 2, 2013


Yes, it's important to realize that, even if the Universe turns out to not care about Naturalness, it will not be true that our mathematics is incapable of describing the Universe, or that physics is wrong. What it means is that we do not get any insight into what conditions exist at extremely high energies that drive physics down where we live. If there is no further discovery at the LHC that informs the solution to Naturalness, I think the most likely explanation is that there is still a solution that would be made apparent if we could probe higher energies.

However, all the solutions I mentioned postulated new physics at the weak scale: the scale of the Higgs mechanism. If whatever the solution is is not at that scale, I have no clue as to what scale I'd need to investigate to find the answer. Is to 10 TeV? If so, awesome, I can imagine building a collider that probes 10 TeV (the LHC will be 14 TeV center-of-mass energy after the upgrade, but because it's a proton-proton machine, not all of the energy is used to make new particles. Past a few TeV the LHC sensitivity will fall rapidly). Is it 100 TeV? If so, well.... we COULD do that, in a political climate that is not this one. 1000 TeV? Need amazing new technologies. 10^6 TeV? 10^12? Now we're just proper fucked, and if the Universe doesn't care about Naturalness, why should the answer lie at the reachable shallows of the ocean of energy scales, and not way out in the depths?

Though it may seem to the outsider that the LHC was a very expensive fishing expedition, the only reason it was built was because a solid theoretical argument was made that, given our technology, we could discover this new particle, which would give us a better insight into the way the Universe works. That argument was first made inside the physics community, and after everyone was on board (which was not hard given that getting physicists to agree on anything is like herding cats), we made the argument to political leaders that for scientific, economic, and social reasons it is important for the involved nations to have a vibrant scientific community that includes particle physics (again an argument that historically has had resonance across the political spectrum), and the LHC would allow us to answer a question that was important for the continued existence of that community. Given the costs and benefits we laid out, we got the funding. We also had high hopes - due to the Naturalness argument - that the LHC would propel us to the next frontier of particle physics and thus keep the field cruising along for the foreseeable future, but that was not explicitly part of the sell.

The LHC has done the job we promised it would, and will continue to into the future. There is much we do not yet know about the Higgs, and there appears to be strong political support in some nations for a precision ILC to continue this role into the next couple of decades. The fear among physicists is that this is it. We found the Higgs, which we knew existed, but we will get no further hints. Without those hints, the field will not fall in line for a new collider experiment, and we will not continue as we have. That doesn't mean there isn't an answer, just that we may never find it. That's perhaps the primal fear of theorists now: that we'll never, ever, get to know the solution. Then there's the fact that, yes, I believe there it is important for functioning nations to have a vibrant physics research community, and without these questions to drive us, our research will dry up and the nations will be poorer for it. However, none of us are going to go lie to Congress and say "no no, build us the mega-LHC" just for the sake of having an experiment to keep us limping along, if we cannot make a convincing scientific argument the the sphere of knowledge would be significantly enhanced at the end.

That said, it's not all doom and gloom. We found the Higgs. Fuck Yeah, We Rock. We know there is dark matter and dark energy out there. There is new physics. We just need to figure out what it is, and how to measure it. And the LHC is not out of the game yet. There's an energy upgrade coming online in the next few years, way more events to record, difficult signatures to look for in the collisions, and I'm still optimistic. Then again, I am young (still!), so maybe this is just foolish youth speaking.
posted by physicsmatt at 10:28 AM on June 2, 2013 [8 favorites]


If you want to start learning it, I'd start with Leonard Susskind's new book, 'The Theoretical Minimum' and then go on to his series of lectures on YouTube from Stanford, which is like hundreds of hours long, and covers everything from classical and statistical mechanics to quantum mechanics, cosmology and the standard model, and string theory. You'd also want to learn multi-variable calculus, linear algebra and group theory as well as advanced geometry, but Susskind kind of explains the math and geometry as he goes along in a somewhat perfunctory way. The only course that I couldn't get a grasp on at all was General Relativity because the geometry is so mind-bending and complicated. Quantum mechanics was actually a lot easier to follow the math on.

The MIT series with Walter Lewin on waves and oscillations and also electromagnetism would also be a good place to start.
posted by empath at 10:29 AM on June 2, 2013 [7 favorites]


The only thing that's clear from all this is that it's time to read the Dirk Gently series again.
posted by neuron at 10:35 AM on June 2, 2013 [2 favorites]


When it comes to physics, I threw up my hands and claimed defeat in tenth grade.

Not to worry. Just focus on F=ma. After that, most of it is just a plug-in.
posted by Twang at 12:01 PM on June 2, 2013


The universe might not make sense. Really? I'm sorry. I was hoping someone would have a handle on it by now.

Okay, but the natural/unnatural part is still interesting. Multiple universes is an attractive trap door here, at least until we can figure out how to work the "wormhole" analogy into a gadget-oriented project for our mechanical engineers, and actually step into the universe next door, or at least send an ansible over there, so that we can discuss it with "them."

The "unnatural" idea remains compelling: For example, are we a Sim City game for some Cosmic Muffin's kid's amusement? Otherwise, are we a cosmic fart (perhaps only one of many), created by some perfectly natural, but as yet obscure, metabioanalogical event?

Fine. Either way, let it be. Let me be in a universe, infinitesimally tiny, that's folded into the 11th dimension, and which resides in a blob of drool dropping from the lip of the Cosmic Dragon. It still leaves the question of what's under the bottom turtle: so we have advanced our perspective exactly one of Zeno's units toward having any real notions about what's going on.

I do appreciate the intellect required to even imagine the components needed to analyze these issues. Then you guys have to invent a math to account for dreams of snakes eating their tails, and so on. It's just that I am several analogies removed from the analogies you guys work with, okay? I'll wait for the guy that can explain this without all the goddam zeros.

Feel free to raid Star Trek history for any terms that might be helpful. I can handle stuff like "reconfigure the gravity plate stabilizers," and "ahhgh...we have to eject the warp core...." for example.
posted by mule98J at 12:31 PM on June 2, 2013 [1 favorite]


Here is an analogy: lets imagine that there was a powerball lottery where every single person, picked the same number and that number came up. How likely do you think it is that something like that just happened by chance?

That is basically what the naturalness problem is, and why people don't like fine-tuning the constants. The more fine tuning you see, the less it looks like the universe just happened to turn out that way.
posted by empath at 1:37 PM on June 2, 2013 [1 favorite]


What a great article.

Two meta-considerations make me suspicious of the 'unnatural universe.'

First, it's an old idea in throughly modern dress, namely, that this is the Best of All Possible Worlds:
Physicists reason that if the universe is unnatural, with extremely unlikely fundamental constants that make life possible, then an enormous number of universes must exist for our improbable case to have been realized. Otherwise, why should we be so lucky? Unnaturalness would give a huge lift to the multiverse hypothesis, which holds that our universe is one bubble in an infinite and inaccessible foam. According to a popular but polarizing framework called string theory, the number of possible types of universes that can bubble up in a multiverse is around 10500. In a few of them, chance cancellations would produce the strange constants we observe.
And second, it leaves the door open a crack for an odd Anselmian Deism: if there's even the slightest, most remote possibility God could exist in any of these 10500 universes, you would certainly expect that possibility to preferentially be made manifest in one of the happy, happy, very, very few such as we inhabit.
posted by jamjam at 2:02 PM on June 2, 2013


There seem to be a ton of people who seem to have no idea how any of this works yet for some reason have strong opinions about it based on the metaphors random reporters use. To extend danny the boy's baking meta-metaphore, it's like people arguing that because bread is "like a car tire" the tiny bubbles in it must be at 30-40 PSI because that's how much air they put in their tires and then someone else says, like, bread comes from plants and someone described the capillaries in plants as 'little straws' so bread must be like a bunch of straws bundled together.
I'm always excited when the physicists have to reevaluate their basic model. I keep hoping that one of these times someone will come up with an explanation for the double slit experiment that actually makes sense.
The double slit experiment makes perfect sense mathematically, and the math is the explanation.
posted by delmoi at 3:30 PM on June 2, 2013 [1 favorite]


Nothing makes any sense, and nature most of all. The only thing that is sensible is the works of man.
posted by Charlemagne In Sweatpants at 4:29 PM on June 2, 2013


It's just that people really like answers to the question "why", except when that answer is "because."
posted by seanmpuckett at 5:24 PM on June 2, 2013 [1 favorite]


I keep hoping that one of these times someone will come up with an explanation for the double slit experiment that actually makes sense.

It's been quite a while since I read this book, so I don't actually remember anymore what the explanation is or why I thought it was so great, but I recall very vividly upon reading Quantum Reality by Nick Herbert that while I had thought I understood the double slit experiment (in non-mathematical terms, thank you very much, delmoi), I really had not up until I read the book, but afterward I did.
posted by Steely-eyed Missile Man at 6:16 PM on June 2, 2013


The double slit experiment makes perfect sense mathematically, and the math is the explanation.

And Copenhagen is so lovely this time of year. But this Einstein fellow seems to have a complaint with you.
posted by localroger at 6:19 PM on June 2, 2013 [1 favorite]


paulsc: there are cosmic rays hitting the Earth continually that produce higher energies than the LHC is capable of. If we were accidentally going to kill us all by turning on the LHC, the Universe would have done it already by now.
posted by physicsmatt at 12:13 PM on June 2

It is nearly bordering on comical that a Universe that could have provided for our evolution could have done so, only so that We flip the switch on the device that creates the anomaly that takes Us out. Because if it wasn't for Us, perhaps the flux of high energy particles that you reference, would never have met the products of the LHC that we evolved to build and operate, in Provence.

You really wanna stand on that tiny crumb of safety apologia, in the service of Big Science? Then you're right there, philosophically, with those 3 recently deceased storm chasers out in Oklahoma, who bet that the incredibly slim chances of a universe that could support tornadoes on a small blue planet surrounding a medium size yellow sun in a nondescript galaxy would, in fact, spawn a big storm of interest to the incredibly improbable life forms on that planet that they themselves represented, and that would, also in fact, be the proximate cause of their demise.

I'm all for you guys chasin' the very biggest and worst tornadoes of physics, in search of glorious and final knowledge, and I think you should be doing it, from now on, somewhere out beyond the orbit of Saturn, while the rest of us duck and cover, safely underground, back here under 50 mile of still breathable atmosphere, and reasonable access to drinking water, food, and temperate climates.

Just because you delight in running into funnel clouds doesn't mean the rest of us need agree with the wisdom of that course of action.
posted by paulsc at 6:51 PM on June 2, 2013


Paul, you're being rude, and you don't know what you're talking about.
posted by empath at 6:59 PM on June 2, 2013 [1 favorite]


I keep hoping that one of these times someone will come up with an explanation for the double slit experiment that actually makes sense.

The double slit experiment makes perfect sense mathematically, and the math is the explanation.

I had thought I understood the double slit experiment (in non-mathematical terms, thank you very much, delmoi), I really had not up until I read the book, but afterward I did.


The difference between quantum and classical motion is that a quantum particle in some sense “feels out” the other paths that are not the extremes, and there’s some sense in which it “travels along” all of them, which can allow for interference.

"I think I can safely say that nobody understands quantum mechanics." -Richard Feynman

To me, saying a single particle simultaneously travels along multiple paths and interferes with itself (or the paths interfere with each other?) seems like nonsense. I can say the words but I'm not sure they have real meaning anymore. Maybe it is possible to describe the particle as a 'probability wave' instead? But postulating the physical existence of a 'probability wave' doesn't seem to make sense either. Perhaps delmoi is right that the mathematics is the only explanation. What lies behind it is entirely a mystery that we shouldn't attempt to describe in any other way, unless engaging in mysticism - which I think is awesome as long as we admit that is what we're doing.
posted by Golden Eternity at 7:29 PM on June 2, 2013


When the LHC switches back on it will work at an collision energy of 14 TeV. By way of contrast the Pierre Auger Observatory expects to see one Ultra high Energy Cosmic Ray with an energy greater than 1x10^18 eV every one to two weeks over an area of 3000 sq km. That's a cosmic ray with about a 100,000 times the energy of the highest energy that the LHC can create (and of course it will see many many more at lower energies similar to what the LHC can create). That means that about 12,000 of these ultra high energy particles has hit the Earth every single day for the last 4.5 billion years, yet we're still here.

So to recap the LHC is a bit like switching on a fire hose on the beach. It may be the biggest assed fire hose that man has every created, but it is insignificant compared to the ocean breaking on the same beach. As we're not worried about the ocean destroying the beach we really shouldn't worry about the fire hose.
posted by Long Way To Go at 7:53 PM on June 2, 2013 [1 favorite]


Paul, you're being rude, and you don't know what you're talking about.
posted by empath at 9:59 PM on June 2

"... As we're not worried about the ocean destroying the beach we really shouldn't worry about the fire hose."
posted by Long Way To Go at 10:53 PM on June 2

I live on the extended delta of a river running into the Atlantic, in a place about 9 feet below expected storm surge of a Cat 2 hurricane. Not a day goes by I don't keep a weather eye out, and worry about the fragility of beaches that I regularly visit, in the face of the occasional fury of oceans, and the relative merits of fire hoses. Were it not for the mighty pumps at the end of my street, belonging to a local utility, my front yard would still be sea marsh, and my backyard the seasonal home of shrimp.

For some people, watching certain beaches in recent human memory, fire hoses, and little more, were all that mattered.
"... Arriving at the plant at 2am, the squad split into three. One of their Scorpion fire trucks went as close as it could to the seashore, to suck up the water needed. Another drove to within six feet of the reactor building itself, to do the actual spraying. The third fire engine was parked in between, as a relay point for the half-mile of yellow fire hose they were using.

“It was far worse than I expected. Everything was covered in rubble,” Mr Fukudome said. “There were concrete blocks everywhere, all the manhole covers had popped out, for some reason, and the road was impassable. We couldn’t drive down to pay out the hose from the sea. So we had to run, carrying the hose, half a mile to the sea, in total darkness. ...”


Thank what ever you thank when you can't locate a proximate force to thank, that the sea they sought existed, and was only a half mile away.

But folk farther away were still hoping for fire hoses, too. Just because your odds run out at one experimental site on any given day, doesn't mean shit doesn't happen elsewhere, for similar causes, too. You have to account for all that hurt, in the same mathematics that describe the probability of brilliant new findings, if you're an honest scientist, or fund source for science.

I'm not against Big Science, per se, but I am distrustful of Science that is impatient. It's not necessary that I or anyone living, or that my children, or their children, or their children (as I've happily recently learned of), will know the Big Answer, or not, before proudly jumping into their final holes in the ground, or fires of cremation, etc. It seems to me that the first artifact of the very biggest of Big Science should be Caution with a capital C. To see the end of any movie, you, or your progeny, have to be around for the credits.

Don't talk to me about The Answer. I've no conviction that I'll live to see to it, or that it will be meaningful to me, even if you young bloods find it.

Talk to me about the Long March, and I'll believe you're on the track of Things Worth Knowing.
posted by paulsc at 8:54 PM on June 2, 2013


Thanks for the explanations physicsmatt. I'm not going to claim to have followed more than 50% but I think I've got the gist.

Tell Me No Lies: well, the issue is that we’ve had the predictions for the Higgs Boson’s properties for about 30 years. [...] The issue is that [the predictions have not been fully met] as of yet. Which is starting to get people mighty nervous.

I see this attitude in theoretical physics (the nervousness in the article being a prime example) a lot and it always confuses me. If the observations are accurate then we did -not- find the Higgs Boson that was predicted. In fact it seems likely that the Higgs Boson that has been predicted and theorized about was a dead end. We'd have an unexpected but tangible result; this is exactly the type of situation where breakthroughs are made and our understanding of existing models are changed forever.

In my book that would be friggin' great. Juicy new data to tackle old problems. I could see some concern from people who have hung their careers on the Higgs Boson existing as predicted but for everyone else I would think it would be party time.

And frankly I think finding something unexpected would justify the LHC far better than just confirming something we thought we knew. "Pushing the edges of science" and all that.
posted by Tell Me No Lies at 9:44 PM on June 2, 2013 [1 favorite]


[Comment deleted; try to discuss without calling other people "insane." Thanks.]
posted by taz at 10:19 PM on June 2, 2013


As we're not worried about the ocean destroying the beach we really shouldn't worry about the fire hose.
Technically oceans can destroy beaches.
Don't talk to me about The Answer. I've no conviction that I'll live to see to it, or that it will be meaningful to me, even if you young bloods find it.

Talk to me about the Long March, and I'll believe you're on the track of Things Worth Knowing.
Scientists don't really care what you think, actually.

Did you own a cathode-ray TV? You know the big heavy ones with curved glass fronts? Those are particle accelerators. They blast electrons at the screen, and use big electromagnets to aim those electrons at the screen to draw the image.

The LHC basically works the same way. It uses magnets to move charge particles in a circle and smashes them into each-other. That's all it does. Unless you think your TV might destroy the universe, you have no reason to think the LHC will either.
But folk farther away were still hoping for fire hoses , too. Just because your odds run out at one experimental site on any given day, doesn't mean shit doesn't happen elsewhere, for similar causes, too
Arguing from metaphor is a bad idea. You can use them to illustrate points in an argument, but it's just a huge mess when people start to argue the metaphorical points or how to match the metaphor to the original precisely, it ends up being ridiculous like someone said getting physicists to agree on stuff was like herding cats, that does not mean physicists should be spayed and neutered.

Also, you're undermining your argument anyway. The original metaphor was cosmic rays : ocean :: particle collider : hose. So according to your argument by metaphor extension cosmic rays can be bad but particle accelerators can be good, even necessary. And actually just like the ocean can destroy the beach, energy from space can destroy the earth (say, from a nearby supernova). In fact, some people think some of the extinction events in the fossil record may have been caused by excess cosmic rays caused by one.

However, the LHC can't put out fires or do anything directly useful as far as I know, other then SCIENCE. So it's not like a fire hose at all.
You really wanna stand on that tiny crumb of safety apologia, in the service of Big Science? Then you're right there, philosophically, with those 3 recently deceased storm chasers out in Oklahoma
Those guys were trying to figure out how to better predict the path of storms, and supposedly their work has helped greatly and already saved many people's lives.
I'm all for you guys chasin' the very biggest and worst tornadoes of physics,
These are not the 'biggest and worst tornados of physics'. What's happening in the LHC isn't dangerous at all.

If you want to be distrustful of science and imagine that it's dangerous, that's your choice. But no one really has any reason to listen to you.
posted by delmoi at 11:24 PM on June 2, 2013 [1 favorite]


"Scientists don't really care what you think, actually. ..."

Except when they want their educations financed, or money for grandiose experiments they themselves can't afford.

"... If you want to be distrustful of science and imagine that it's dangerous, that's your choice. But no one really has any reason to listen to you."
posted by delmoi at 2:24 AM on June 3

Well, of course, science can be dangerous. Mdme. Curie went down by terrible cancer, which only much later, after hundreds of glow-in-the-dark watch dial painter girls all died of cancers directly related to the same radium salt poisoning Mdme. Curie inadvertently discovered, was recognized as a possible "cause."

And still, I do not only believe in science, but support it, on the fringe, with my dollars and my own time, where I can. I think vaccinations are a good way to keep large numbers of people alive, in the present. I'm all for improved efficiency and widespread commercialization of photovoltaic mechanisms, as made possible by research. Hell, I happily eat genetically modified food, urge others to do the same, and imagine that the boys and girls in white coats at Pennington, or one of their competitors, will develop the perfect lawn "no mow" grass variety, given enough time and technique. Perhaps I should be against GMO foods, and lawns that don't need mowing, but, I dunno, my experience with organisms that need human input is that they don't turn Frankenstein, but tend to die out, without lots of continuing care and reason to exist.

And I don't know, for sure, that relegating high energy physics experiments to beyond the orbit of Saturn can guarantee the future of mankind. Perhaps they do belong in the Kuiper Belt, but I've just suggested extra-Saturnal space as a starting point, since we've, as a race, already sent a couple of things there, and at just beyond the orbit of Saturn, the rest of us, back here on a small blue marble, might have chance to duck, a few hours after those of you out on the experimental frontier had already observed things going very wrong.

So it takes 500 orbits of this planet to re-build the LHC at Saturn +something orbital distance. Small delay, if you can even call it that, compared to the history of our race, or the potential we have remaining in the Long March forward.
posted by paulsc at 12:04 AM on June 3, 2013


"... Did you own a cathode-ray TV? You know the big heavy ones with curved glass fronts? Those are particle accelerators. They blast electrons at the screen, and use big electromagnets to aim those electrons at the screen to draw the image. ..."
posted by delmoi at 2:24 AM on June 3

I still watch CRT based TVs daily. Inside those CRTs, just behind the big glass screens, they all have metallic masks (#6 element in this Wikipedia illustration), that catch and absorb most of the accelerated particles produced by the electron gun.

And I still wonder, idly, from time to time, about reports of folk whose mortal ends came about in front of their TVs, without better explanation. I am very skeptical that spontaneous human combustion while watching Twilight Zone is the definitive cause, but what Twilight Zone episodes I do watch, I watch only on LED TVs.

Just sayin'. Improved technology is generally worth waitin' for...
posted by paulsc at 12:43 AM on June 3, 2013


Except when they want their educations financed, or money for grandiose experiments they themselves can't afford.
In theory, they only need 51% of the population, not every single person. And in a coalition style democracy they only need a small, passionate base. There are number of side benefits from mega-science that politicians may be interested in as well. It provides jobs, (the shuttle program was a good example, scientifically completely worthless but produced a shit-ton of jobs) and countries also use them as status symbols.
Well, of course, science can be dangerous.
Science can be dangerous, to the scientists. Even today space missions can be dangerous. You see the film Chasing Ice and you can see scientists putting themselves in danger. But ethical scientists are not going to put other people in danger. Also you were arguing that the LHC was dangerous, despite the fact that you don't seem to understand anything about it, not 'science' in general.
after hundreds of glow-in-the-dark watch dial painter girls all died of cancers directly related to the same radium
People knew radiation was dangerous long before that happened. That was criminally negligent management, not 'science'.
And I don't know, for sure, that relegating high energy physics experiments to beyond the orbit of Saturn can guarantee the future of mankind.
You do understand that "high energy" physics here means 2.2 millionths of a joule, right? A joule is the kinetic energy that an apple will have after falling for one meter, the energy in the accelerator is about equal to the kinetic energy of a droplet of water traveling at 20 centimeters per second. They do this over and over again, in order to collect a lot of data. It's not dangerous to the scientists or anyone else.

(apparently each beam has about 110 billion of those 7 TeV protons, so while the energy of each reaction is small overall the total energy is equivalent to 77kg of TNT according to this, but you would have to stick part of your body into the actual tube while it's on, which I assume is impossible)
I still watch CRT based TVs daily. Inside those CRTs, just behind the big glass screens, they all have metallic masks (#6 element in this Wikipedia illustration), that catch and absorb most of the accelerated particles produced by the electron gun.
So? As you can see the detector that surrounds the reaction is quite large. The real problem with the TV are the gamma rays that get produced, and to stop them the glass is actually lead. The electrons themselves would be stopped by the air if they got out of the TV somehow, or cause a lightning style spark. Either way I don't really see what this has to do with whether or not the LHC can destroy the earth. The electrons are still colliding with things inside the TV, which produces the light.

Ultimately, if you don't think it's safe, whatever. You can't prove anything to someone who doesn't understand the argument.
posted by delmoi at 1:06 AM on June 3, 2013


"... so while the energy of each reaction is small overall the total energy is equivalent to 77kg of TNT according to this ..."
posted by delmoi at 4:06 AM on June 3

Although, according to your same link, that's enough energy, continually applied, to push the 88,000 ton Nimitz class US aircraft carrier Harry S. Truman along at about 5.6 knots. Nothing approaching dangerous there, although anytime the Harry S. Truman is operating at half that speed, you can bet a fleet maneuvering qualified naval officer is in command, and lotsa other eyes, above and below sea level are wide damn open.

To say nothing of the fact that the entire steel bulk of the Harry S. Truman even at 5.6 knots relative speed to an incoming cosmic particle, might not be as attractive a target of mischief as protons circulating in storage rings of the LHC, at "0.999999991 the speed of light at top energy." As many here know, some kinds and states of matter seemingly only readily interact with other kinds and states of matter that they preferentially "like," i.e. "fast" neutrons vs. "slow" neutrons interacting with various kinds of fissile materials, and moderators, etc. I'm of the opinion, that we just don't know, because of the limitations of our technology, what happens when we ram relativistic speed protons, and their collision result particles, into highly energetic cosmic rays in the naturally occurring flux of the Universe, for anyone to be smug about safety. Color me Cautious Old Man, in purple, if you canonically Do, and show your work, and CV documenting your extensive experience at colliders operating well above LHC last run parameters, please.

We (meaning not only the scientific community, which is still in discussion/theorizing mode, but the larger world) don't even fully understand or agree what happened in the last LHC runs, yet.

The FPP here is about the failure of the current crop of physics wizards to explain the last run of the LHC, which, at their direction, was run to energies well above prior experimental limits. Even the 125 GeV "discovery" of a "Higgs boson" from those runs is under discussion/dispute in many circles. That same LHC is scheduled to start up again in 2015, having been rebuilt for still higher energies, on the basis, from what I gather, mainly, of scientific curiosity.

How about we don't throw the switch for another 50 years, even if we don't relocate the physics community to life in Saturnal confines? A little time for math to percolate, for other views to arise, for folk still in grade school to learn the experiments, and the data, and think anew.

There can be real advantages to being a medium life expectancy race, in a very strange, and daily ever more strange, Universe, if only a little patience is employed.
posted by paulsc at 2:21 AM on June 3, 2013


[Folks, it's fine to take side conversations to email, please try to be a part of the conversation already in progress.]
posted by jessamyn at 10:13 AM on June 4, 2013


Physics’s pangolin: Trying to resolve the stubborn paradoxes of their field, physicists craft ever more mind-boggling visions of reality
posted by homunculus at 1:35 PM on June 6, 2013 [1 favorite]


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