Tuesday, August 16, 2016

A physics extravaganza

For today's post: exciting goings-on from the wide world of physics. We'll begin with "Latest search for dark matter draws a blank."

If only the hunt were this simple
Dark matter, you'll recall, is hypothesized stuff that (a) exhibits its presence through its gravitational effects on familiar/normal matter, for example on the rotational characteristics of galaxies and (b) doesn't interact with electromagnetic radiation, of which ordinary light is an example (hence the "dark" part of the name). Dark matter is most often expected to take the form of (many) tiny particles of a type(s) yet to be observed.

Alas, after several searches, no such particle(s) has been discovered. The experiments -- including the latest, per the above link -- do not disprove that such particles exist, but they do narrow down the mass range such particles might inhabit. Likewise interesting on this topic, "Why dark matter still proves difficult to detect."

Speaking of particles not found, a much ballyhooed "bump" in the data at the Large Hadron Collider -- possible harbinger of some "new" physics beyond the Standard Model -- has been discounted as mere statistical fluke. See "New particle hopes fade as LHC data 'bump' disappears." It pays to be cautious about exciting or provocative results. (A study reporting "We didn't find anything new," on the other hand, is apt to be true.)

Likewise not found: another dark-matter particle candidate, so-called sterile neutrinos that interact only with gravity. See "Search for fourth type of neutrino turns up none." The Standard Model continues to hang in there ...

Electromagnetism at work
A dominant theme in modern physics is unification, in which seemingly disparate phenomena are shown to be related. Electricity and magnetism were thought to be separate forces until James Maxwell demonstrated their inter-connectedness -- and so, we now speak of electromagnetism.

Physicists have since found and demonstrated an underlying relationship unifying the so-called "weak force" (involved in the process of radioactive decay) with the electromagnetic force. Some theorists have suggested the possibility of a further unification, connecting the electro-weak force with the so-called "strong force" (that binds quarks together to form protons and neutrons, and that binds nuclei together despite the mutual electrical repulsion of protons). Every conceptual experiment that might demonstrate the latter candidate unification appears far beyond the capacity of current (or any reasonably achievable) technology.

Despite decades of trying, theoretical efforts to combine the aforementioned fundamental forces with yet another fundamental force, that of gravity, have failed dismally. (String theories, of which there are many, are such attempts -- and no string theory yet offered has been amenable to experiment.) Perhaps we should stop looking. That, at least, is the premise of the thought-provoking article, "Grand Unification May Be A Dead End For Physics."

Those of you keeping score at home will have noticed I've mentioned four fundamental forces of nature: electromagnetism, weak, strong, and gravitational. Just to be wacky for a moment, and taking a trip into fringe science (with a dark-matter component to it), consider this speculation, "A Fifth Force: Fact or Fiction?"

How small can we go?
How long can Moore's Law (loosely speaking, the steady improvement in semiconductor-device miniaturization) continue? Past predictions of the trend's demise have proven premature. This prediction has a slightly better claim than most to credibility -- it's a forecast of the semiconductor industry itself. See "Transistors Will Stop Shrinking in 2021, Moore’s Law Roadmap Predicts."

And for our final item of this post -- and as long as we're looking "out there" -- consider that "‘Tractor beams’ build atom-by-atom assembly in mid-air." As in:

Physicists have manipulated 50 individual atoms at once in a dramatic upscaling of a technique vital to quantum computing.

Truly, we live in interesting times.

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