Did You Ever Really Look At Your Hand?
October 13, 2020 1:54 PM   Subscribe

This is the image of time that is familiar to us: something that flows uniformly and equally throughout the universe, in the course of which all things happen. A present that exists throughout the cosmos, a “now” that constitutes reality. The past for everyone is fixed, is gone, having already happened. The future is open, yet to be determined. Reality flows from the past, through the present, toward the future—and the evolution of things between past and future is intrinsically asymmetrical. This, we feel, is the basic structure of the world ... This familiar picture has fallen apart, has shown itself to be only an approximation of a much more complex reality. The End of Time by Carlo Rovelli

Some related Carlo Rovelli posts from what we think of as the past
posted by chavenet (21 comments total) 16 users marked this as a favorite
Just as 99.999% of the strongest steel plate is emptiness between atoms, returning to kill your grandfather (for likely very good reasons) is just as unlikely as passing your hand through the steel plate (uninjured).

Just did not see any new observation, time changes due to acceleration, a vital element that needs to be calculated many times a second in your phone or many more of us would be driving into lakes. But the arrow of time, that it's one way, no going back, seems pretty darned constant, we are all headed towards the heat death of the universe.
posted by sammyo at 2:08 PM on October 13, 2020 [1 favorite]

Counterpoint from Tim Maudlin (2017) -- but not directed at Rovelli, since this interview with Maudlin was ... earlier.
posted by Jonathan Livengood at 2:14 PM on October 13, 2020 [2 favorites]

This is sounding like the first couple weeks of an Irish literature class I had (the best course I've ever taken on anything in my life) in which the professor was trying to get a bunch of half-awake college students to think like pre-Christian Irish Celts. One of the many concepts about which the Celts thought differently, he argued, was time, and how it affected the context by which you could refer to an object.

For example - on my windowsill right now is a geranium in a pot. If I mentioned the geranium, you'd just take it as read that I was talking about a geranium and that was it. If there was a specific context I'd want you to keep in mind as you thought about the geranium, I'd have to add that for you ("It was a geranium I got from my mother" or "it's a pain in the ass to water" or "it's the same color as the basil in the other window" or what have you).

In Celtic writing, my professor argued, my mentioning the geranium would include all of those contexts at the same time - the fact that it was in my windowsill, the fact that I got it from my mother, its color - as well as all other possible contexts; maybe my mother planted it the same year my father broke his elbow. Maybe it was something an old boyfriend caught himself staring at one morning while he was in bed with me waiting for me to wake up. Maybe there's a tiny worm living in the soil that I don't know about and it's just doin' its thing. All of those different things are invoked simply by my bringing up the geranium in a conversation. It's kind of like if the aliens from Darmok met the aliens from Trafalmadore.

And this was the thought process of a supposedly "uncivilized" people. Sounds more to me like they were actually thinking about quantum reality way sooner than anyone, and it's just that the people with the bigger weapons were so far behind them that they wrote their ideas off as madness. And that now makes me wonder how many other times that must have happened throughout history.
posted by EmpressCallipygos at 2:40 PM on October 13, 2020 [11 favorites]

EmpressCallipygos - can you explain more how just mentioning the geranium contained everything about it? (Or, if that’s too much, can you offer some resources to understand it better?) Sounds amazing. Thank you.
posted by anshuman at 2:51 PM on October 13, 2020 [2 favorites]

EmpressCallipygos - can you explain more how just mentioning the geranium contained everything about it? (Or, if that’s too much, can you offer some resources to understand it better?)

Unfortunately, the only resources I have are baffled notes and an imperfect memory from that class....we only spent a couple weeks dealing with the Celtic mindset before jumping on ahead to trace the ensuing 500 years of Irish history, so that by the time Yeats and other early Irish writers were trying to revive "true Irish literature" right before Ireland's independence, they no longer had a complete understanding of everything the myths they were reading actually meant. Darmok and the way the Trafalmadorans think in Slaughterhouse Five are probably the best illustrations I could think of. There was just always this subliminal awareness of all the connections an object you referred to could make to everything else.

This was about the literature, as well, which may have been more fancy and hifalutin than ordinary conversation.
posted by EmpressCallipygos at 2:57 PM on October 13, 2020 [2 favorites]

I have an unorthodox view that if the future isn’t fixed (and I do believe it isn’t) then the past isn’t either. There are possible pasts as well as possible futures.

For instance, Comic Book Guy has a revelation about his life just before France nukes Springfield. To Homer afterwards, there’s nothing in now to distinguish the past where Comic Book Guy did from the one where he didn’t.

I have better arguments for this based on the impossibility of infinite information (there was a recent FPP on that) but it won’t matter whether I elaborate on it or not.
posted by sjswitzer at 2:59 PM on October 13, 2020 [2 favorites]

sjswitzer, are you saying that if there's more than one future that could possibly result from our present, that implies there's more than one past that could have led to our present? Wow.
posted by straight at 3:04 PM on October 13, 2020 [5 favorites]

I have a problem with the idea that perception of time reflects increasing entropy because the second law only applies to a closed system. On earth, we’re bathed in a flow of solar energy that drives processes that seemingly defy entropy: life for instance. And many things are recurring or cyclical like day after night or the seasons.

Certainly entropy is observable in, say, my kitchen after dinner. But then I do the dishes, put them away and my kitchen is much as it was before.

There’s something naggingly unsatisfactory to me about entropy driving the perception of time since the world we live in draws on its energy flux to oppose entropy.
posted by sjswitzer at 3:14 PM on October 13, 2020 [2 favorites]

Straight: exactly
posted by sjswitzer at 3:14 PM on October 13, 2020 [1 favorite]

Something like the Butterfly effect except maybe sometimes a second butterfly cancels the first.
posted by sjswitzer at 3:18 PM on October 13, 2020 [1 favorite]

(My unorthodox view is that the present is sorta like an infinitely thin soap bubble, and neither the past or future exist in a physical sense. All of our information about the past is via lingering physical phenomena; there's no way to directly observe events that have already happened. You can watch a video tape, sure, but that's just some nicely aligned electrons, not the actual event, which is now lost.)
posted by kaibutsu at 3:47 PM on October 13, 2020 [5 favorites]

Our deeply emotional attitude toward time has contributed more to the construction of cathedrals of philosophy than has logic or reason.

Or, you know, literal cathedrals. Few if any who’ve laid the first stone of a cathedral have seen it completed.
posted by sjswitzer at 4:39 PM on October 13, 2020 [1 favorite]

if there's more than one future that could possibly result from our present, that implies there's more than one past that could have led to our present

I agree with this view, but the reason I agree with it is exactly because all three ideas - the past, the future, and the present - are ideas; they're very very approximate approximations of what's actually going on, which is inherently too detailed to be knowable.

The more detail we have available about what is happening, the more heavily constrained will become both our correct predictions about what will happen and our correct accounts of how how that did happen.

And I have no reluctance at all to extend this concept way beyond what is literally reasonable, in order to arrive at "only what did happen, did happen; only what is happening, is happening; only what will happen, will happen" - a rather block-universe-flavoured tautology which, if taken seriously, would prima facie seem to justify Laplace's Demon.

In fact I don't think it does. I am perfectly comfortable with the idea of the entirety of my past, my present and my future - and by extension, those of any other observer - being in-principle capable of "coming into focus" as a unitary whole, without branching possibilities, as the detail level increases. Possibility, it seems to me, is itself an idea that only makes sense in the context of uncertainty, and in a theoretically perfectly detailed model of my past and present and future there is no uncertainty so there's only the one possibility.

It seems to me that the main reason why Laplace's Demon would never actually work is practical rather than principled: as you increase the detail (or, equivalently, the scope) of a prediction, the energy required to calculate it increases, and calculating an entire future faster than it can actually turn up will always require far more energy than is available. You always end up with nowhere to put the Demon.

So I'm quite comfortable with the idea that in fact there is no contradiction between determinism in the sense that only what will happen will happen, and free will in the sense that my own lack of information about my own interior state will often force me to abandon causality as a practically applicable reasoning tool for analyzing what it is that I'm about to do.

But all this highfalutin philosophy boils down to is definitional word games that anybody is completely free to play for their own amusement. Where they get more interesting is when we start thinking about whether two observers could ever adopt these same definitions and yet generate observations of reality that there is genuinely no way to reconcile.

Einstein took it as a given that the answer to that would be No. For me it remains an interesting open question, on the basis that if there's ever an irresolvable conflict between what I think is happening and what actually is happening, the smart money's not on me regardless of how good my work has been up to that point.
posted by flabdablet at 5:13 PM on October 13, 2020 [3 favorites]

Did You Ever Really Look At Your Hand?

posted by flabdablet at 5:30 PM on October 13, 2020 [2 favorites]

Counterpoint from Tim Maudlin

He talks a lot of sense. One nit I'd pick, though, is with the idea that there's no natural way to assign a preferred direction in space. This may well be the case within the conceptual frameworks of Newtonian mechanics and special relativity, but as soon as general relativity becomes the appropriate tool to wield I think it's pretty natural to think of gravitational fields as defining preferred directions for spacelike intervals.
posted by flabdablet at 6:22 PM on October 13, 2020 [1 favorite]

the arrow of time, that it's one way, no going back, seems pretty darned constant, we are all headed towards the heat death of the universe

Seems to me that each of us has an arrow on a worldline that would, if we could only remain identifiable enough to have a worldline for a sufficiently long time, eventually intersect the event horizon of some black hole or other.
posted by flabdablet at 6:28 PM on October 13, 2020 [1 favorite]

I think the relativity of simultaneity should put to rest any notion of the unreality of the past, and even the future. My past is your present and vice versa, even here on Earth. In more extreme scenarios, my distant future can be your present or even distant past.
posted by wierdo at 6:29 PM on October 13, 2020 [4 favorites]

It's interesting to me that the article provoked a series of responses consisting of people trying to define time for themselves. I suppose one could give the simple utilitarian answer that the true meaning of "time" varies with how it is put to use. For physicists time is a mathematical construct that differs from our everyday understanding. For me, time is how I keep track of when I need to log in to work tomorrow so I don't get fired. I don't think my boss would accept as an excuse the argument that the true nature of time does not admit a simple present as we understand it because our shared perceptions and the terms of my employment contract don't exist at quantum sizes or relativistic speeds to each other.

Unfortunately, time also only seems to flow in one direction for me, so I can't go back to before this stupid pandemic or to undo some of the poor choices I've made in the past. I suppose I could take comfort in the fact that according to some quantum physicists there is a version of me that isn't in a world experiencing a pandemic or that didn't make those choices, but god dammit I am this version of me whether I want to be or not. I suppose I'm dancing around the hard problem of consciousness now. Someone smarter than me and of a more reductionist bent can probably describe it in terms of my relation with a larger thermodynamic system, but for the moment I merely dance around the hard problem of consciousness, which certain trendy philosophers in my undergrad claim doesn't exist.

Either way, I need a way to tell whether I'm awake or asleep to get up for work tomorrow, and I need a linear measure of time to keep to my work schedule. And I'm always hungry, whatever "I" happen to be.
posted by eagles123 at 8:17 PM on October 13, 2020 [4 favorites]

What if the present we inhabit is only the focus point of time, and behind us, it unravels, ahead of us it lingers like shafts of sunlight in a room, ready to make shadows.
posted by Oyéah at 2:54 PM on October 14, 2020

What if each of us is a locus of awareness moving within an eternal, immutable, overwhelmingly large and detailed reality, and you and I are currently on approximately parallel courses?
posted by flabdablet at 8:22 PM on October 14, 2020

The audiobook of "In Order of Time" is narrated by Benedict Cumberbatch. Even though it was only about 5 hours long, it seemed like I lived with that book and Cumberbatch's voice for a really long time, as there were so many times I had to roll back and re-listen to the bits that sound so counterintuitive that it was like hearing thoughts from an alien.

My coworker later pointed out that Cumberbatch might have got onto the project because as Dr. Strange, he could control time.
posted by of strange foe at 9:21 AM on October 15, 2020

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