Theidlerhour - Bricolage Brain

Physicists often quote from T. H. White’s epic novel The Once and Future King , where a society of ants declares, ‘Everything not forbidden is compulsory.’ In other words, if there isn’t a basic principle of physics forbidding time travel, then time travel is necessarily a physical possibility. (The reason for this is the uncertainty principle. Unless something is forbidden, quantum effects and fluctuations will eventually make it possible if we wait long enough. Thus, unless there is a law forbidding it, it will eventually occur.)

Michio Kaku

Just for your info, actually he’s talking (without quoting) about the Gell-Mann’s Totalitarian Principle:

“Everything not forbidden is compulsory.”

(via scienceisbeauty)

“What do you play?”

“The Clarinet, you?”

“I play the fucking HAMMER”

We don’t want to conquer space at all. We want to expand Earth endlessly. We don’t want other worlds; we want a mirror. We seek contact and will never achieve it. We are in the foolish position of a man striving for a goal he fears and doesn’t want. Man needs man!

Solaris (1972), Andrei Tarkovsky (via giveintosin)

This analysis book was published in 1970. At some point in its life before I purchased it last summer (a life which spanned 18 years before I was even born, by the way), it was owned by someone who read every page, and wrote enthusiastic comments in the margins next to particularly thrilling conclusions to proofs. I love this subject, and I share every sentiment with this unknown stranger. I too love the drama of confusion and the triumph of understanding, and I love sharing that experience with this person with whom I have a rare and important commonality. Wherever you are book-commenting analysis enthusiast, I think the world of you. I hope you have a happy life full of abstract mathematics.

Imagine a droplet sitting on a rigid surface spontaneously bouncing up and then continuing to bounce higher after each impact, as if it were on a trampoline. It sounds impossible, but it’s not. There are two key features to making such a trampolining droplet–one is a superhydrophobic surface covered in an array of tiny micropillars and the other is very low air pressure. The low-pressure, low-humidity air around the droplet causes it to vaporize. Inside the micropillar array, this vapor can get trapped by viscosity instead of draining away. The result is an overpressurization beneath the droplet that, if it overcomes the drop’s adhesion, will cause it to leap upward. For more, check out the original research paper or the coverage at Chemistry World.  (Video credit and submission: T. Schutzius et al.)

Mars will lose its largest moon, but gain a ring

Mars’ largest moon, Phobos, is slowly falling toward the planet, but rather than smash into the surface, it likely will be shredded and the pieces strewn about the planet in a ring like the rings encircling Saturn, Jupiter, Uranus and Neptune.

UC Berkeley postdoctoral fellow Benjamin Black and graduate student Tushar Mittal estimate the cohesiveness of Phobos and conclude that it is insufficient to resist the tidal forces that will pull it apart when it gets closer to Mars.

Mars tugs differently on different parts of Phobos. As Phobos gets closer to the planet, the tugs are enough to actually pull the moon apart, the scientists say. This is because Phobos is highly fractured, with lots of pores and rubble. “Dismembering it is analogous to pulling apart a granola bar”, Black said, “scattering crumbs and chunks everywhere.”

Read more about the fate of Phobos

Today is the 100th anniversary of Einstein’s presentation of general relativity’s field equations to the Prussian Academy of Sciences. The equations demonstrated the relationship between the local curvature of spacetime and the energy and momentum within that area of spacetime. The first image shows the way that Einstein first presented the equations in his 25 November 1915 paper, where G_im is the Ricci tensor; g_im, the metric tensor; T_im, the energy–momentum tensor for matter; and κ is proportional to Newton’s gravitational constant. The second image shows a modern full version of the equation where R_μν, is the Ricci curvature tensor; R, is the scalar curvature; g_μν, is the metric tensor; Λ, is the cosmological constant; G, is Newton’s gravitational constant; c, is the speed of light in vacuum; and T_μν, is the stress–energy tensor. For more about Einstein’s development of the equations, we have a article available from our November issue: http://dx.doi.org/10.1063/PT.3.2979

via: Physics Today