Optics basics: refraction

In short, refraction is the bending of a ray of light when it passes from one medium to another. Unlike optical phenomena like diffraction and interference, which usually require careful experimental preparation to be observable, refraction is readily seen all around us. If you’ve ever seen a seemingly bent straw in a glass of water, you’ve seen the effect of refraction.

Technique gets clear images from light reflected off blank paper

When light passes through a turbid medium, the photons scatter off the inhomogeneities. If the source is incoherent, like an ordinary incandescent or fluorescent bulb, this results in a blurry image—if any image can be formed at all. If the light is coherent, such as a laser, scattering results is a speckled pattern. In either case, a clear view of the original object may not be possible. This spells doom for medical imaging, astronomy, and other applications. (The authors also suggested it gets in the way of peering through shower curtains. We at Ars condone such voyeuristic pursuits for consenting scientific partners only).

Super-cold metals show ‘strange’ behavior

Georgia Tech researchers, writing in the journal Science, report surprising behavior exhibited by nanometer-scale clusters of the metal niobium when they are cooled to below minus 424 degrees Fahrenheit.

I would not be surprised if the “nanometer-scale clusters” aspect of the investigation has some significant impact on the behavior. A surface represents a loss of symmetry present in a bulk material; surface effects are of interest to many physicists. A nanometer-scale cluster is going to have a fair amount of surface relative to its volume. So it’s probably not just that it’s cold.

There is something and not nothing

I really like this post. It’s well-written (not surprising, since it’s Roger Ebert) and gives the perspective of someone who is interested in science but understands that he will be limited in understanding the full depths of the science, for lack of a complete background. It think that’s significant. For many there is indifference, and for others (as we venture toward crackpot-land), there is an attitude that if I cannot understand it, it must be wrong. For the latter, there is interest in science — passion, even — but only if it’s already within their grasp. No acknowledgement of the giant body of experiment, on whose shoulders we stand.

As I understand computers, this discovery could not have been faked. Numbers went in, numbers came out, and the numbers indicated what the scientists predicted that would discover.

If they had not, that would have been a huge disappointment, coming at the end of such a magnificent and expensive experiment. The Collider is useful for many other experiments, but never mind: An explanation for mass in the universe would still have been lacking.

I think that while there’s a fair amount of truth to this, it’s also true that had the Higgs not been found, there would have been some euphoria that there is definitely new physics to go and discover.

There’s one other part caught my eye that Mr. Ebert hints at, concerning the scientific method.

Here is where we get to the heart of the question. The scientific method has no interest in belief. What you believe is of interest only from an autobiographical viewpoint. Scientists (1) regard a phenomenon they would like to explain, (2) suggest a hypothesis to explain it, and (3) devise an experiment to test their hypothesis.

There’s a subtlety here that cannot be overlooked, especially in the context of his comments on belief — doing good science is not just about gathering evidence that supports your hypothesis. A good hypothesis makes specific predictions about what is to be found, and what is not to be found. A good experiment will eliminate competing hypotheses as well as confirming the one in question, leaving only one valid explanation … if the data are as expected. If you don’t get that result, then you have falsified the hypothesis, and it needs to be modified or discarded.

If all evidence can be viewed as supporting your hypothesis, then you aren’t doing science at all.

In discussing the Higgs, Ebert quotes Lawrence Krauss

Krauss continues: “…if there exists an otherwise invisible background field permeating all of space, then the particles that convey some force like electromagnetism can interact with this field and effectively encounter resistance to their motion and slow down, like a swimmer moving through molasses. As a result, these particles can behave as if they are heavy, as if they have a mass.”

I have heard this explanation before, and it sounded like the aether had been resurrected — but I also know that the theory is going to be consistent with relativity, so there can’t be any way you can use the Higgs field as a frame of reference. So you are never at rest with respect to the Higgs field. If the effect is truly from motion through the field, you couldn’t be, because then you would have no mass, and would move at c. But that conundrum is as almost far as my understanding goes; I have a tenuous grasp of the symmetry arguments but don’t ask me to explain them.