A black hole in a bathtub and other analog experiments

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Studying impossible systems with analogues

How do you study a phenomenon that cannot be replicated on Earth? You study one that has nothing to do with it, but looks incredibly similar mathematically.

For Physics World:

Some experiments simply can’t be done. It’s a hard truth that physicists learn to face at an early stage in their careers. Some phenomena we want to study require conditions that are out of reach with our current techniques and technologies.

This is especially true when physicists make predictions about the very early universe. Theories hypothesize, for example, that certain particles may have been created during this high-energy period, but our colliders are just not powerful enough to replicate those conditions, which means we cannot create the particles ourselves. The physics that exists only in or around black holes poses a similar problem. Since these massive objects are very far away (the closest known is thousands of light-years distant) and would require hitherto unfeasible amounts of energy to make in the lab, we’re not able to test our theories about them.

[Read the rest at Physics World]

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Why the death of black holes is a big problem for physics

[ This blog is dedicated to tracking my most recent publications. Subscribe to the feed to keep up with all the science stories I write! ]

Part 4 of my 4-part series on black holes for Medium members is up; part 1 is herepart 2 is here, and part 3 is here. If enough of you read, they may keep me around to write more, so please read and share! And yes, the title is a John Donne reference, because I was an English minor and am required to make literary references as often as I can get away with.

Gravity Be Not Proud

The discovery that black holes emit particles and might eventually evaporate threw theoretical physics into chaos. Here’s why.

For Medium:

Hawking ended up being one of the very rare ALS patients to survive the condition, at the eventual cost of being confined to a wheelchair and communicating primarily through a computer. And his work on black holes — along with the work of a small handful of other physicists — opened up a new field of research in quantum gravity.

The most shocking discovery to come out of Hawking’s work: Black holes can emit radiation and can eventually evaporate.

Unfortunately for physicists, the radiation from a real black hole is too faint to be seen, and even a smaller black hole, like the ones seen by LIGO, would take a mind-blowingly long time to evaporate. However, the prediction of this Hawking radiation and death of black holes exposed a major problem in theoretical physics, one that is still unsolved today.

Read the rest at Medium…

Stephen Hawking, black holes, and scientific celebrity

The active galaxy Centaurus A, rendered in several different types of light. Note in radio waves (the central image at right), the galaxy itself seems to disappear, replaced by crossing jets of radio-emitting jets. Those are produced by the supermassive black hole at the galaxy’s core.

The active galaxy Centaurus A, rendered in several different types of light. Note in radio waves (the central image at right), the galaxy itself seems to disappear, replaced by crossing jets of radio-emitting jets. Those are produced by the supermassive black hole at the galaxy’s core.

For the upcoming ScienceOnline 2014 meeting, I’m leading a session titled “Reporting Incremental Science in a World that wants Big Results“. It’s an important topic. We who communicate science to the general public have to evaluate stories to see if they’re worth covering, then translate them in such a way that conveys their significance without hyping them (ideally at least). That’s challenging to do on deadline, and we’re not always or maybe even usually experts on the topics we report. I know a fair amount about cosmology and gravitational physics, but very little about galactic astronomy or planetary science — yet I must write about them, because it’s my job.

So Stephen Hawking’s recent talk on black holes is an interesting case study. I won’t rehash the whole story here, but I wrote not one but two articles on the subject yesterday. Article 1 was in Slate:

Hawking’s own thinking about black holes has changed over time. That’s no criticism: Evidence in science often requires us to reassess our thinking. In this case, Hawking originally argued that black holes violated quantum mechanics by destroying information, then backed off from that assertion based on ideas derived from string theory (namely, the holographic principle). Not everyone agrees with his change of heart, though: The more recent model he used doesn’t correspond directly to our reality, and it may not have an analog for the universe we inhabit. The new talk suggests he has now moved on from both earlier ideas. That’s partly what raises doubts in my mind about the “no event horizons” proposal in the online summary. Is this based on our cosmos or yet another imaginary one of the sort physicists are fond of inventing to guide their thinking? In my reading, it’s hard to tell, and in the absence of a full explanation we are free to project our own feelings about both Hawking and his science onto the few details available. [Read more…]

Article 2 was a follow-up on my own blog:

But at the same time, we have to admit that nobody—not Nature News, not Slate.com—would have covered a paper this preliminary had Hawking’s name not been attached. Other people are working on the same problem (and drawing different conclusions!), but they can’t command space on major science news sites. So, by covering Hawking’s talk, we are back on that treacherous path: we’re showing how science works in a way, but we risk saying that a finding is important because somebody famous is behind it. [Read more…]