This is all sorts of mental gymnastics. I can't quite pin down what's happening with the particles and the significance of their interactions and decay. But I'll be damned if I don't try to get better a better grip on it.
#time #timetravel #science #knowledgefrontiers
Jonathan Langdale originally shared this post:
Back to the future
I've been trying to come to grips with the idea of time symmetry and time-reversal. +Sean Carroll writes an interesting post about the recent B meson "arrow of time" experimental result that was announced recently.
"The reason why it’s an impressive experiment is that it’s very difficult to directly compare the rate of one process to its precise time-reverse. You can measure the lifetime of a muon, for example, as it decays into an electron, a neutrino, and an anti-neutrino. But it’s very difficult (utterly impractical, actually) to shoot a neutrino and an anti-neutrino directly at an electron and measure the probability that it all turns into a muon."
What I'm struggling with is the idea of time reversal as distinguished by
1. Going forward in time and constructing a muon from by-products coming together in the same way they decay
vs
2. Going backwards in time from the by-products to a muon.
There seems to be a fundamental difference between these two ideas. If you're still going forward in time, is that really a time symmetry? It seems like it would be a different process than actual time-reversal.
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Time-Reversal Violation Is Not the “Arrow of Time” | Cosmic Variance | Discover Magazine
arxiv | Looks like the good folks at the BaBar experiment at SLAC, feeling that my attention has been distracted by the Higgs boson, decided that they might be able to
]]>Maybe we’ll start paying attention to history after we repeat it a few more times.
#history #rome #campaignreform #citizensunited #money #politics #culturalperspectives
Jürgen Hubert originally shared this post:
Relevant, as I have recently been reading about the Roman Republic.
How Political Campaign Spending Brought Down the Roman Republic
Two years after the Supreme Court’s decision in Citizens United, which allowed unlimited corporate and union money into American politics, there is one line that continues to echo: “The appearance of …
]]>In Musk's vision, the ambitious Mars settlement program would start with a pioneering group of fewer than 10 people, who would journey to the Red Planet aboard a huge reusable rocket powered by liquid oxygen and methane.
]]>A field full of pyramids, but on a micro scale. Each of the pyramids hides a living cell. Thanks to 3D micro- and nano scale fabrication, promising new applications can be found.
http://phys.org/news/2012-11-capturing-cells-micro-pyramids.html
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Library of Congress pulls diaries, letters from those who experienced Civil War for exhibit
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