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Normal, All Over Again
Infinities in quantum field theory, and renormalization. Living with Infinities by Steven Weinberg
[N]ew techniques of calculation were developed that manifestly preserved the principles of special relativity at every step, and it was recognized that the infinities could be absorbed into a redefinition, called a renormalization, of physical constants like the charge and mass of the electron. Dyson was able to show (with some technicalities cleared up later by Salam and me) that in quantum electrodynamics and a limited class of other theories, the renormalization of a finite number of physical parameters would actually remove infinities in every order of perturbation theory — that is, in every term when we write any physical observable as an expansion in powers of the charge of the electron, or powers of similar parameters in other theories. Theories in which infinities are removed in this way are known as renormalizable. They can be recognized by the property that in renormalizable theories, in natural units in which Planck’s constant and the speed of light are unity, all of the constants multiplying terms in the Lagrangian are just pure numbers, like the charge of the electron, or have the units of positive powers of energy, like particle masses, but not negative powers of energy.
Aye, Robots
Robotic systems continue to evolve, slowly penetrating many areas of our lives, from manufacturing, medicine and remote exploration to entertainment, security and personal assistance. Developers in Japan are currently building robots to assist the elderly, while NASA develops the next generation of space explorers, and artists are exploring new avenues of entertainment. Collected here are a handful of images of our recent robotic past, and perhaps a glimpse into the near future. (32 photos total)
Omphaloskepsis
Revealed: The secrets of belly button fluff
After three years of research, Georg Steinhauser, a chemist, has discovered a type of body hair that traps stray pieces of lint and draws them into the navel.
Dr Steinhauser made his discovery after studying 503 pieces of fluff from his own belly button.
Michael Faraday's GUT
Michael Faraday, grand unified theorist? (1851)
The common thread of many of [Faraday’s] discoveries is their goal: demonstrating that all the physical forces of nature are but different manifestations of a single, ‘universal’ force. This idea was a surprisingly modern one for Faraday’s time, and is known today as a unified field theory. Such research was likely on the minds of many researchers of that era, however: once Ørsted discovered that a magnetic compass needle could be deflected by an electric current, the notion that all forces might be related was a tantalizing dream. Faraday went further than any of his contemporaries in realizing that dream, and experimentally cemented the link between electricity and magnetism and light. Faraday was by no means done, however, and in 1851 he published the results of his attempts to demonstrate that electricity and gravity are related!
This is Highly Significant
The idea of significant figures is that when you’re doing experimental work, you’re taking measurements – and measurements always have a limited precision. The fact that your measurements – the inputs to any calculation or analysis that you do – have limited precision, means that the results of your calculations likewise have limited precision. Significant figures (or significant digits, or just “sigfigs” for short) are a method of tracking measurement precision, in a way that allows you to propagate your precision limits throughout your calculation.
Another Condensed Matteron
Another in my continuing series trying to explain some condensed matter concepts in comparatively jargon-free language. So far I’ve talked about electron-like quasiparticles, phonons, and plasmons. Now we consider magnons, also known as “spin waves”. A magnon is another collective excitation, like a phonon or a plasmon, that may be described by a wavelength (or equivalently a wavevector) and an accompanying frequency.
Looking Up at Bob
Mocking What You Don't Understand
A discussion of recent neuron-deficient attacks on science.
The tricky thing about most basic research, though, is that you don’t always know what you’ll get out of it when you release the funds. Such research often opens up new and surprising avenues that themselves then spin off important innovative technologies that no one could have predicted. (In Jindal’s case, he wasn’t even attacking basic research, but rather, research of obvious disaster safety import. Not even my caveats can help him.)
In an ideal world, then, specific scientific appropriations would hardly be above criticism—but you would also have to make a cogent argument for why they’re not the best use of our investments. You wouldn’t just mock that which you don’t understand