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Thread: Backwards Univers?

  1. #1
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    Backwards Univers?

    Is this article pseudoscience? It says that ANITA in Antarctica has detected tau neutrinos which prove a parallel universe where time runs backwards (if I understand it).

    https://themindunleashed.com/2020/05...-backward.html
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

  2. #2
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    Tau neutrinos are regularly detected, they are part of the Standard Model. What was detected in 2016 was what looked like a cosmic ray shower but directed upwards rather than downwards. This is tough to explain so some whacky ideas were thrown out. Axions, sterile neutrinos or just an unlikely event from a particle that passed through the Earth. One of the least likely was the idea that they are related to a time reversed interaction. Guess which of the ideas the magazines focused on?

    The result doesn't prove anything really. It is an interesting result that might indicate something outside the Standard Model, but on its own it is not enough. So that meant a bunch of people threw out their own favourite speculations and someone saw an opportunity to write a catchy headline.

  3. #3
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    I think it's more pseudojournalism than pseudoscience--it's a really garbled presentation of one hypothesis about the origin of these taus. They're consistent, by a chain of inference, with Neil Turok's work on a CPT-symmetric Big Bang and the production of right-handed neutrinos. There's a New Scientist article (paywalled) that gives a more coherent account.
    (Oops, overlapped with Shaula.)

    Grant Hutchison

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    The ANITA articles I've seen have nothing about this backward universe.
    Do good work. —Virgil Ivan "Gus" Grissom

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    Quote Originally Posted by Roger E. Moore View Post
    The ANITA articles I've seen have nothing about this backward universe.
    It's been around for a while:
    Upgoing ANITA events as evidence of the CPT symmetric universe (2018)
    CPT-Symmetric Universe (2018)

    Grant Hutchison

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    I guess it's akin to an automotive engineer saying he witnessed a Volkswagen Beetle going in reverse at 60mph.

    There are a few possible explanation for this, involving some creative engineering, to be sure - but there is, of course, the possibility that the Beetle was actually going backward in time.
    As Shaula says, guess which one they wrote about.

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    I guess I'm just being ignorant again, but I thought that neutrinos were incredibly hard to detect because they rarely interact with normal matter. That's why they have special detectors in deep mines etc. So why is it a surprise that they passed through the earth?

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    Quote Originally Posted by headrush View Post
    I guess I'm just being ignorant again, but I thought that neutrinos were incredibly hard to detect because they rarely interact with normal matter. That's why they have special detectors in deep mines etc. So why is it a surprise that they passed through the earth?
    It's to do with the neutrino energy detected. High energy neutrinos have a very low chance of transmission through the Earth.

    Grant Hutchison

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    Quote Originally Posted by grant hutchison View Post
    It's to do with the neutrino energy detected. High energy neutrinos have a very low chance of transmission through the Earth.

    Grant Hutchison
    Thanks. I guess a lot of high energy physics changes relatively quickly as new discoveries are made.

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    If there were a universe created at the time of the Big Bang that travelled backwards in time, it would be nearly 28 billion years away from us by now (along the time axis), and getting further away all the time.

  11. #11
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    Quote Originally Posted by headrush View Post
    Thanks. I guess a lot of high energy physics changes relatively quickly as new discoveries are made.
    Headrush. Yep. Earlier neutrino detectors, relied on collisions between neutrinos and electrons in the target mass. Those electrons, and sometimes ancillary particles produced traveled faster than light could in that target media ( for example, water), creating a burst of photons from Cherenkov radiation. That burst set off photodetectors, and with certain discrimination cuts, an event was recorded....like the events from SN1987a.
    But, in 1974, a prediction was made that neutrinos might also interact with the nucleus as a whole, not just the electron shells. That was called coherent scattering, and the likelihood of measuring it at the time was deemed experimentally too tricky because of the large background noise.
    Enter the Spallation Neutron Source at Oak Ridge, TN. By splattering protons on a target, intermittent bursts of neutrons could be produced, eventually leading through a series of decay schemes to give an intermittent flux of neutrinos. Those neutrinos could be carefully monitored only during the time intervals when they arrived on target. That allowed removing background counts that accumulated during a non-duty period to be removed, and enabled researchers to finally see Coherent Neutrino/ Nucleus scattering.
    Surprise!Surprise! The cross-sections turned out to be six orders of magnitude larger ( one million)..than the electron/ neutrino scattering at the energy run for the SNS lab. That means you can detect neutrinos with a backpack size detector while hiking the Appalachian trail, if you have a small Mazda generator along for power.

    The scientists paper is under Akimov et AL in Nature, and the tech talk I heard at MIT was by Kate Scholberg from Duke at the Thursday Physics Colloquiem, Apr. 2018.
    There's a good article and photo, here from Juan Collar, U. of Chicago, and you can see that the 32 lb detector is pretty compact.
    Since the recent paper by Timmes et al, indicated that if Betelgeuse were to go supernova, it would be detectable at this distance with Coherent scattering during the prompt neutrino burst, and from the paper by Patton, Lunardini, Farmer, and Timmes, the late phase increase of beta process neutrinos as the nucleosynthesis began to increase by a factor of 100 in the waning hours of the proto supernova ... ( about 10 to 5 hours before the explosion).. would also be detectable according to Kate Scholberg's , and Akimov's work.
    Collar, Juan...see: https://news.uchicago.edu/story/worl...ions-particles

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    Coherent neutrino scattering is most relevant to low energy neutrino interactions. And the cross section was no surprise - it was what the Standard Model predicted. It wasn't seen before because it is hard to see the nuclei in the detector recoil at low energies where the interactions are optimised for detection. Once the detector technology caught up the expected signal was seen. It was a neat piece of work and one that confirmed Standard Model predictions and put limits on the extra physics people hoped to find in the neutrino sector.

    See: https://arxiv.org/ftp/arxiv/papers/1708/1708.01294.pdf
    From there:
    Characteristic signatures in energy and time, predicted by the Standard Model for this process, are observed in high signal-to-background conditions.
    This possibility would exist only as long as the momentum exchanged remained significantly smaller than the inverse of the nuclear size (Fig. 1A), effectively restricting the process to neutrino energies below a few tens of MeV.

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