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Posts Tagged ‘particle physics

“There is a size at which dignity begins”*…

 

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The spectrometer for the KATRIN experiment, as it works its way through the German town of Eggenstein-Leopoldshafen in 2006 en route to the nearby Karlsruhe Institute of Technology

 

Isaac Asimov dubbed neutrinos “ghost particles.” John Updike immortalized them in verse. They’ve been the subject of several Nobel Prize citations, because these weird tiny particles just keep surprising physicists. And now we have a much better idea of the upper limit of what their rest mass could be, thanks to the first results from the Karlsruhe Tritium Neutrino experiment (KATRIN) in Germany. Leaders from the experiment announced their results last week at a scientific conference in Japan and posted a preprint to the physics arXiv.

“Knowing the mass of the neutrino will allow scientists to answer fundamental questions in cosmology, astrophysics, and particle physics, such as how the universe evolved or what physics exists beyond the Standard Model,” said Hamish Robertson, a KATRIN scientist and professor emeritus of physics at the University of Washington…

Physicists get small: “Weighing in: Physicists cut upper limit on neutrino’s mass in half.”

* Thomas Hardy, “Two on a Tower”

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As we step onto the scales, we might spare a thought for Max Karl Ernst Ludwig Planck; he died on this date in 1947.  A theoretical physicist, he is best remembered as the originator of quantum theory.  It was his discovery of energy quanta that won him the Nobel Prize in Physics in 1918.

220px-Max_Planck_1933 source

 

Written by LW

October 4, 2019 at 1:01 am

Adventures in Cosmology: Starting out Simply…

Why was entropy so low at the Big Bang? (source: Internet Encyclopedia of Philosophy)

Back in 2010, SUNY-Buffalo physics professor Dejan Stojkovic and colleagues made a simple– a radically simple– suggestion:  that the early universe — which exploded from a single point and was very, very small at first — was one-dimensional (like a straight line) before expanding to include two dimensions (like a plane) and then three (like the world in which we live today).

The core idea is that the dimensionality of space depends on the size of the space observed, with smaller spaces associated with fewer dimensions. That means that a fourth dimension will open up — if it hasn’t already — as the universe continues to expand.  (Interesting corollary: space has fewer dimensions at very high energies of the kind associated with the early, post-big bang universe.)

Stojkovic’s notion is challenging; but at the same time, it would help address a number of fundamental problems with the standard model of particle physics, from the incompatibility between quantum mechanics and general relativity to the mystery of the accelerating expansion of the universe.

But is it “true”?  There’s no way to know as yet.  But Stojkovic and his colleagues have devised a test using the Laser Interferometer Space Antenna (LISA), a planned international gravitational observatory, that could shed some definitive light on the question in just a few years.

Read the whole story in Science Daily, and read Stojkovic’s proposal for experimental proof in Physical Review Letters.

As we glance around for evidence of that fourth dimension, we might bid an indeterminate farewell to Ilya Prigogine, the Nobel Laureate whose work on dissipative structures, complex systems, and irreversibility led to the identification of self-organizing systems, and is seen by many as a bridge between the natural and social sciences.  He died at the Hospital Erasme in Brussels on this date in 2003.

Prigogine’s 1997 book, The End of Certainty, summarized his departure from the determinist thinking of Newton, Einstein, and Schrödinger in arguing for “the arrow of time”– and “complexity,” the ineluctable reality of irreversibility and instability.  “Unstable systems” like weather and biological life, he suggested, cannot be explained with standard deterministic models.  Rather, given their to sensitivity to initial conditions, unstable systems can only be explained statistically, probabilistically.

source: University of Texas

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