In a Multiverse, What Are the Odds? "Testing the multiverse hypothesis requires measuring whether our universe is statistically typical among the infinite variety of universes. But infinity does a number on statistics." (previously) [more inside]
World's longest-running experiment captures elusive tar pitch drop fall on video after 84 years of waiting — though, sadly, too late for physicist and former pitch drop custodian Prof. John Mainstone, who passed away last year.
A Black Hole Mystery Wrapped in a Firewall Paradox - "A paradox around matter leaking from black holes puts into question various scientific axioms: Either information can be lost; Einstein's principle of equivalence is wrong; or quantum field theory needs fixing." [more inside]
Now, a technological advance has made it possible for physicists to test the idea. They plan to build a time crystal, not in the hope that this perpetuum mobile will generate an endless supply of energy (as inventors have striven in vain to do for more than a thousand years) but that it will yield a better theory of time itself.Nobel laureate Frank Wilczek's "somewhat embarassing" idea will be put to the test as scientists try to build time crystals.
The Nature of Computation - Intellects Vast and Warm and Sympathetic: "I hand you a network or graph, and ask whether there is a path through the network that crosses each edge exactly once, returning to its starting point. (That is, I ask whether there is a 'Eulerian' cycle.) Then I hand you another network, and ask whether there is a path which visits each node exactly once. (That is, I ask whether there is a 'Hamiltonian' cycle.) How hard is it to answer me?" (via) [more inside]
Brian Greene's Fabric of the Cosmos is online in its entirety on NOVA's website, in four one-hour episodes. Time, Space, Quantum Mechanics, Multiverses.
The concept of time as a way to measure the duration of events is not only deeply intuitive, it also plays an important role in our mathematical descriptions of physical systems. For instance, we define an object’s speed as its displacement per a given time. But some researchers theorize that this Newtonian idea of time as an absolute quantity that flows on its own, along with the idea that time is the fourth dimension of spacetime, are incorrect. They propose to replace these concepts of time with a view that corresponds more accurately to the physical world: time as a measure of the numerical order of change.
"It doubtless seems highly paradoxical to assert that Time is unreal, and that all statements which involve its reality are erroneous. ... I believe that time is unreal. But I do so for reasons which are not, I think, employed by any of the philosophers whom I have mentioned, and I propose to explain my reasons in this paper." ~McTaggart, The Unreality of Time, 1908. (Bonus: The Kant Song.)
Raft to the Future: An article about the weirdness of physical models of the universe, how that weirdness correlates to the inherent incompleteness of mathematical systems, and how time itself can emerge at the fringes of these incomplete models.
Imagining the Tenth Dimension (Flash). 10th dimensional physics and string theory don't get any easier than this.
We are hosting the first and only Time Traveler Convention at MIT in one week, and WE NEED YOUR HELP! Anyone plan to attend?
The cable clock. This clocks tells time, just like any other clock, but the movement of the hands is hypnotic and beautiful. To physicists, time is defined by quantum mechanics. A photon with energy h (Planck's constant) behaves as though it were oscillating once per second. For Philosphers, time is less concrete, and they love to talk about it. Western society lives by the clock - does it make a difference if this is the kind of clock that you live by? After all, everyone knows that time is money. If you have to be a clock watcher, does it help if the clock is as calming as the Cable Clock is?
A bold paper published in the August issue of Foundations of Physics Letters seems set to change the way we think about the nature of time and its relationship to motion and classical and quantum mechanics. The work also appears to provide solutions to Zeno's paradoxes. (Via Kurzweilai.net. More inside...)