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Particle Physicists Confirm Arrow of Time Using B Meson Measurements 259

Posted by Unknown Lamer
from the one-way-trip dept.
ananyo writes with bad news for John Titor. From the article: "Four years after its closure, researchers working with data from the Stanford Linear Accelerator Center's particle physics experiment BaBar have used the data to make the first direct measurement confirming that time does not run the same forwards as backwards — at least for the B mesons that the experiment produced during its heyday. The application of quantum mechanics to fundamental particles rests on a symmetry known as CPT, for charge-parity-time, which states that fundamental processes remain unchanged when particles are replaced by their antimatter counterparts (C), left and right are reversed (P), and time runs in the reverse direction (T). Violations of C and P alone were first seen in radioactive decays in the 1950s, and BaBar was used to confirm violations of CP in B meson decays in 2001. To keep CPT intact, that implies that time reversal is also violated, but finding ways to compare processes running forward and backward in time has proven tricky. Theoretical physicists at the Universityof Valencia in Spain worked with researchers on BaBar to exploit the fact that the experiment had generated entangled quantum states of the meson Bzero and its antimatter counterpart Bzero-bar, which then evolved through several different decay chains. By comparing the rates of decay in chains in which one type of decay happened before another, with others in which the order was reversed, the researchers were able to compare processes that were effectively time reversed version of each other. They report in Physical Review Letters today that they see a violation of time reversal at an extremely high level of statistical significance."
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Particle Physicists Confirm Arrow of Time Using B Meson Measurements

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  • by Anonymous Coward on Monday November 19, 2012 @07:59PM (#42033885)

    Thus is our treaty written; thus is agreement made.
    Thought is the arrow of time; memory never fades.
    What was asked is given; the price is paid.

  • Dear Slashdot: (Score:4, Insightful)

    by Anonymous Coward on Monday November 19, 2012 @08:18PM (#42034095)
    Bet you wish you had unicode now, eh?
  • Re:Inverted Truth (Score:0, Insightful)

    by Anonymous Coward on Monday November 19, 2012 @08:26PM (#42034193)

    There is an unmatched parenthesis in your comment. Somehow I think the missing parenthesis is necessary to help people parse the sentence correctly.

  • CPLEAR (Score:5, Insightful)

    by Roger W Moore (538166) on Monday November 19, 2012 @10:17PM (#42035477) Journal

    Arrow of Time confirmed... Wheel of Time fans disappointed.

    Physicists on the CPLEAR experiment will be disappointed as well - they actually discovered this effect (called T-violation) back in the 1990's before Babar was running by looking at kaon oscillations produced in low energy proton/antiproton collisions [Phys. Lett. B 444 43 (1998)]. So Babar was certainly not the first experiment to see the "arrow of time" although it is the first to do so using B mesons.

  • by socceroos (1374367) on Monday November 19, 2012 @11:57PM (#42036461)
    No, not quite - stereotyping/generalising is an element of sexism in many cases, but not the definition of it. I don't find, in any way, that the books elevate one sex over the other as more valuable.
  • by fredprado (2569351) on Tuesday November 20, 2012 @12:09AM (#42036555)
    Hardly. Recognizing that there are differences between the sexes is common sense. Judging people's values and defining their roles solely by their sexes is sexism.

    Women and men are not equal in everything. Trying to see equality in everything because it fits your notion of symmetry, fairness or whatever is self-delusion.
  • by silentcoder (1241496) on Tuesday November 20, 2012 @04:19AM (#42037969) Homepage

    >Hardly. Recognizing that there are differences between the sexes is common sense. Judging people's values and defining their roles solely by their sexes is sexism.

    Those "differences" are provably superficial and purely cultural -as well proven by other cultures having radically different role expectations from sexes and both sexes playing into those different expectations with the same level as they do to the ones in ours.
    Hell even in our own subcultures this view is greatly challenged. Consider for example the highly androgynous gender-roles of the metal and goth cultures - or the outright girly look of glam metal (which then ironically became equated with having the "guts to be glam" - the MOST masculine thing a man could do was to act feminine).

    No my friend, the differences between the sexes exist only in the physical form.

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