Back to the future

Time to Reverse Time
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. 
.

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

Another Fear Inducing “US is the Roman Empire” Comparison

Another Fear Inducing US is the Roman Empire Comparison 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… Continue Reading

Library of Congress pulls diaries, letters from those who experienced Civil War for exhibit

Can't believe it took them this long to release archives in order to gain a more personal account of the US Civil War. Library of Congress pulls diaries, letters from those who experienced Civil War for exhibit #war #history http://www.washingtonpost.com/national/library-of-congress-pulls-diaries-letters-from-those-who-experienced-civil-war-for-exhibit/2012/11/24/323f9d5c-364d-11e2-92f0-496af208bf23_story.html?Post%2Bgeneric=%3Ftid%3Dsm_twitter_washingtonpost WASHINGTON — Letters and diaries from those who lived through the Civil War offer a… Continue Reading

Entry to Video Contest: The Past Re-imagined as the Future – “Make Space, Not War”

After several weeks of planning and tossing around a handful of ideas, 2 weeks of dedicated work on combining two ideas into one new idea, and a grueling 3 day edit fest, I have completed my video remix for the Free Music Archive and Prelinger Archives hosted video contest “Sound for the Moving Image : The Past… Continue Reading

Stumbling through Space History

I just learned a very insightful piece of historical information – the Soviets beat the USA into space due to their lack of technology. What? Yes. They were building massively huge Intercontinental ballistic missiles (ICBM) in order to launch their awkwardly large and unsophisticated nuclear arsenal. The US was streamlining the tech. Going for quality and accuracy over quantity… Continue Reading