Some Old Time Fraccing

Posted on by

No, not fracking. Space-filling curves, which are fractal in nature.

Curves… in… spaaaace! (1890)

[S]uch a curve is quite unusual, and won’t quite look like anything encountered before. In fact, the complete curve is impossible to visualize, since it literally fills the square and, in the process, takes an infinite number of twists and turns along the way. However, we can get a feel for its behavior through an iterative process that generates curves of increasing complexity that approach the true space-filling curve in the limit of infinite iterations.

Don't Handle With Care

Posted on by

Antifragility and Anomaly: Why Science Works

I think I like this terminology.

Antifragility is the true opposite of fragility. Unlike mere robustness, it is the ability to actually profit from misadventure. A porcelain cup is fragile, and shatters if dropped. A plastic cup, being robust, will not be any the worse for such an experience, but it will not be any the better for it either.

…

Among the things that Taleb lists as fragile are scientific theories. Scientific theories are indeed vulnerable to disproof, since they must be tested against reality. The simplest way to describe this is to say that they must be falsifiable by experience, a criterion associated with the name of Karl Popper. In the popular imagination at least, however well established the theory may be from past experience, it could at any time be refuted in the future by a single observation that differs from what is theoretically predicted. If so, scientific theories would indeed be fragile, since they could not survive a single shock.

But that is not what really happens. Well-established theories have already explained a wide range of observations, and will not readily be destroyed by a single counterexample. On the contrary, they usually emerge all the stronger for accommodating to it.

Of course theories can break, but it requires contrary evidence in such a way that we can’t simply narrow the scope of the idea, i.e. the holes are in all through it rather than at an edge. Phlogiston, for example, or the early models of the atom.

By Failure, I Assume You Mean Success

Posted on by

Ask Ethan #29: The Most Famous Failed Science Experiment

So, then, the reasoning went, if light is a wave — albeit, as Maxwell demonstrated in the 1860s, an electromagnetic wave — it, too, must have a medium that it travels through. Although no one could measure this medium, it was given a name: the luminiferous aether.

Sounds like a silly idea now, doesn’t it? But it wasn’t a bad idea at all. In fact, it had all the hallmarks of a great scientific idea, because it not only built upon the science that had been established previously, but this idea made new predictions that were testable!

Ethan does a pretty thorough job of this, as usual, with the possible exception of not fully explaining that the observation of aberration was how scientists knew we couldn’t be at rest with respect to an aether — in their paper, Michelson and Morley specifically mention how their null result refutes Fresnel’s model of aberration (involving partial aether dragging and which was backed by an experiment carried out by Fizeau in 1851).

What I really object to here is the notion that this was somehow a failed experiment. The hypothesis failed, but it was not their hypothesis! While it’s quite likely that Michelson and Morley expected a result that was consistent with us moving through an aether, the more idealized view an experimentalist is supposed to take is to not expect a specific result at all, lest one become biased in gathering and interpreting data. That the experiment was clever and thorough enough to be able to refute an incorrect hypothesis means it was wildly successful, rather than a failure.

Trust Me, Maybe? Redux

Posted on by

Chad has a post up about peer-review in the context of the BICEP2 results about inflation: Review and Replication

What ultimately matters, after all is not review but replication– that is, when somebody else tries to do the same experiment, do they get the same results? This is where issues with statistical flukes usually sort themselves out, and that’s not a problem that can be fixed by any amount of refereeing. A journal referee can look for obvious gaps in the analysis, but will never get to the level of detail of a repeat experiment or a follow-up measurement.

This has some overlap with something I wrote a few weeks back (Trust Me, Maybe?) wherein I argued that peer review is a demarcation where you can start taking claims seriously, but I realize I was thinking more about theory awaiting confirmation rather than experiment. Chad’s point that there are experimental efforts where peer review will be a formality of sorts, because we already know the experiment was carefully done, is correct. What’s important here is replication.

This reminds me of a description I recently saw (but I don’t know its origin): Peer review is a spam filter. In a case like BICEP, we’re already pretty sure it’s not spam.

Not Sticking the Landing

Posted on by

Physics Fail in Record-Setting Car Jump Attempt

Everything seems to be fine for the first two thirds of the flight. But then the sound of the engine dies and the car starts to rock forward. Those two things are intimately connected.

This is something I noticed in the animated movie The Incredibles, where they got this part right, despite all of the suspension of disbelief required elsewhere in the movie: when the van drops free of the rocket, Mr. Incredible stomps on the gas and the van tilts back, which is at least qualitatively what you’d expect.

A Good Week for Waves Continues

Posted on by

‘Waves’ detected on Titan moon’s lakes

Dr Barnes, from the University of Idaho in Moscow, US, used a mathematical model to investigate whether the features in the image were compatible with waves.

“We think we’ve found the first waves outside the Earth,” he told the meeting.

“What we’re seeing seems to be consistent with waves at just a few locations in Punga Mare [with a slope] of six degrees.”

He said other possibilities, such as a wet mudflat, could not be ruled out.

This Won't Affect the Consumer Price Index

Posted on by

Detection of Waves in Space Buttresses Landmark Theory of Big Bang

Reaching back across 13.8 billion years to the first sliver of cosmic time with telescopes at the South Pole, a team of astronomers led by John M. Kovac of the Harvard-Smithsonian Center for Astrophysics detected ripples in the fabric of space-time — so-called gravitational waves — the signature of a universe being wrenched violently apart when it was roughly a trillionth of a trillionth of a trillionth of a second old. They are the long-sought smoking-gun evidence of inflation, proof, Dr. Kovac and his colleagues say, that Dr. Guth was correct.

I imagine that this will trigger an inflationary period of blog posts and science articles by those who are far more qualified than I to explain the results.

Somebody Understands Quantum Mechanics?

Posted on by

Nobody understands quantum mechanics? Nonsense!

Interesting take on this, presenting other examples of people who had an “interpretation” of reality and forced their model to accommodate it and make the model work according to their notion of how the world should work. I also agree with the conclusion, that interpretations may be a useful stepping stone for investigation, but until someone comes up with a testable prediction unique to one interpretation, you can’t claim that it’s right.

Related: his previous entry, Reality and the Interpretations of Quantum Mechanics

A Cautionary Tale

Posted on by

Related to Monday’s post about copyright and plagiarism:

Photographer wins $1.2 million from companies that took pictures off Twitter

Joshua Kaufman, a lawyer for AFP, blamed the infringement on an innocent mistake and said the Twitter user who posted Morel’s photos without attribution bore responsibility for the error. The AFP editor, Kaufman said, believed the pictures were posted for public distribution.

Tis points out a pitfall of one of the big issues — posting without attribution. You can’t simply assume that an unattributed picture is in the public domain, and if you want to use the picture you need to track down the copyright owner. As I had relayed: www does not mean public domain (before Pedantic Man swoops in, yes, Twitter doesn’t actually use www in its address. But the concept is the same)

Getting Real

Posted on by

Guest Post: Is It Solipsistic in Here, or Is It Just Me?

Our first major breakthrough came when we realized that physics can pin down what’s real and what isn’t. It’s one of those things that’s somehow stupidly obvious and yet deeply profound: something is real if it’s invariant. That is, something is real if it remains unchanged from one reference frame to the next. Just look at a rainbow. You’ll see one in the sky if you’re in just the right reference frame with the Sun shining in from behind you, and droplets of water in the atmosphere refracting the light. It’s pretty, but good luck trying to grab it. A rainbow is not a physical object stapled to the sky. It’s a product of your reference frame. Which is to say, it’s not real.

An interesting viewpoint, and one I don’t recall coming across before, probably because I don’t do physics that ventures into this area. One of the stumbling points I’ve observed in discussions about what is real is the definition of real — real as in a physical object instead of a concept, or real as in not an illusion, i.e. not fake? Here it looks like the former: a rainbow is not a physical object, hence it’s not real. But it’s not an illusion, not some bit of fakery. The effect (refraction of light) is real.

There are plenty of not-real (not physical object) things in physics; the author concludes that basically all of it falls into this category, but that’s not the point of physics. Physics exists to tell us how nature behaves, not what it is. Electric fields and phonons and lots of denizens of physics models don’t physically exist. There is no claim that they do. It’s that nature behaves as if they existed, and since that lets us predict and retrodict what happens, that’s good enough.