Tag Archives: physics

Stephen Hawking: ‘There are no black holes’

In its stead, Hawking’s radical proposal is a much more benign “apparent horizon”, which only temporarily holds matter and energy prisoner before eventually releasing them, albeit in a more garbled form.

more on nature.com.

A sensationally titled article summarizing an upcoming paper from Hawking that doesn’t really deny the existence of black holes, but may redefine what they are.

Peter Higgs: I wouldn’t be productive enough for today’s academic system

Higgs said he became "an embarrassment to the department when they did research assessment exercises". A message would go around the department saying: "Please give a list of your recent publications." Higgs said: "I would send back a statement: ‘None.’ "

Peter Higgs emerges as an honest and very likeable character. A short but interesting interview.

Temporally Quaquaversal Virtual Nanomachine by Damian Conway

Watch in horror as Damian writes a Perl program to extract square roots using nothing but quantum mechanics, general relativity, and the very fabric of the space-time continuum. Along the way we’ll also investigate: Wittgenstein’s dark secret; the diminishing returns of physical computation; Roman philosophy; when Super Science Adventures go wrong; the greatest Lego kit of all time; the secret identity of Sith; carbon logic vs silicon logic; the giants of 1930′s physics; elementary spin-half quanta under relativistic motion; CAT scans; Will Smith; bongos; drunken bets involving penguins; algorithmic consistency; God’s dice and the problem of free will; intrinsic self-inconsistency; the many worlds outside Copenhagen; and the inventor of stage diving.

Hilarious and educating presentation that demonstrates that Perl is no less crazy (and amazing) than quantum physics.

What the Dalai Lama can teach us about temperatures below absolute zero

Here’s the short answer. It is possible to create negative temperatures. It was actually first done in 1951. But it’s not what it sounds like – these temperatures aren’t colder than absolute zero. For instance, you can’t keep cooling something down to make its temperature drop below absolute zero. In fact, as I’ll try to explain, objects at a negative temperature actually behave as if they’re HOTTER than objects that are at any positive temperature.

Explanation of temperatures below absolute zero. Another brilliant post from the Empirical Zeal science blog.

Falling From The Friendly Skies

Yes, Baumgartner broke the speed of sound, but it wasn’t that big of a deal: he was starting from so high up that he would probably have fallen at least a couple of hundred meters per second even if he’d opened his parachute the moment he jumped.

The physics of high altitude jumps.

Physics World reveals its top 10 breakthroughs for 2011

Steinberg’s work stood out because it challenges the widely held notion that quantum mechanics forbids us any knowledge of the paths taken by individual photons as they travel through two closely spaced slits to create an interference pattern.

This interference is exactly what one would expect if we think of light as an electromagnetic wave. But quantum mechanics also allows us to think of the light as photons – although with the weird consequence that if we determine which slit individual photons travel through, then the interference pattern vanishes. By using weak measurements Steinberg and his team have been able to gain some information about the paths taken by the photons without destroying the pattern.

What happened in physics in 2011, beside almost-but-not-quite search for Higg’s boson and possibly faster than light neutrinos.

Antimatter atoms produced and trapped at CERN

The ALPHA experiment has shown that it is possible to hold on to atoms of antihydrogen in this way for about a tenth of a second: easily long enough to study them. Of the many thousands of antiatoms the experiment has created, ALPHA’s latest paper reports that 38 have been trapped for long enough to study.

Did you notice the most important news of this week?

The Myth of Gravity

If gravity is an “entropic force,” there is no longer a need for physicists to attempt to reconcile general relativity with quantum mechanics, or hunt for the hypothetical graviton (the particle posited to carry the gravitational force just as photons mediate the electromagnetic force), says Paul Frampton, at the University of Tokyo in Japan. Rather, all we need to explain the interactions of particles is the Standard Model of particle physics and entropy.
more on fqxi.org

A new theory claiming that gravity is not one of the four fundamental forces.