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(Medium)   Speed of light needs correcting after photons outpaced by neutrinos. Speed of dark unchanged   ( divider line
    More: Interesting, neutrinos, supernovas, Einstein, speed of light, fine structures, weak forces, astronomers, virtual particles  
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3343 clicks; posted to Geek » on 25 Jun 2014 at 3:53 PM (3 years ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»

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2014-06-25 04:00:22 PM  
2 votes:

DjangoStonereaver: Um....

Considering that the 'speed of light' (IE, the speed of photons) slows down inside a physical medium like,
say, interstellar dust clouds, whereas neutrinos can zip through almost all intervening matter, I don't see
why the theory of relativity needs to be revised in any way.

But I'm not a scientist.

Plus, if it's a supernova, if I Remember right, the neutrino burst occurs *BEFORE* the visible light from the explosion, *because* while the photons are working through all the other gunk that's going to explode (The plasma), the neutrinos, well, don't.

Perhaps the revising isn't "Relativity was wrong!", though, and more "The 8th digit of the speed of light neds to be turned from a 5 to a 6" or something.

/Note: I am not a cosmologist, my field of physics is nano-phsicys/engineering/synthesis.
2014-06-25 02:23:39 PM  
2 votes:
That was a thoroughly interesting read.  Thank you for applying the right tag to it. Given the (unstated in TFA) distance of 168000 light years to SN1987a, the 4.7 hour differential represents a 3.2E-7% difference in the predicted versus observed light arrival time.

Significant for astrophysicists, certainly, and would represent an error of 41 years in the estimated 13B year age of the universe.
2014-06-25 11:39:09 PM  
1 vote:
I'm confused.
2014-06-25 08:39:56 PM  
1 vote:

syrynxx: I thought I recalled the results of the 1987A neutrino/light differential was important because it put an upper limit on the mass of the neutrino at no more than 15 eV (which is not zero but compare to an electron at 511,000 eV).  This is quite a different interpretation, but it seems plausible to me.  Thanks, subby!

Yeah - i think the present limit is .le.2.something eV for the electron neutrino...

CSB (an tl;dr) time. I was an undergraduate at the University of Michigan in 1987, and a physics major making beer money by working with a couple of professors who were principles in the "IMB" experiment. I basically came in ~10-20 hours a week to keep tapes processing, starting simple analysis jobs, doing simple Cerenkov cone fits, etc... IMB was a large cubic hole underground filled with very clean water and surrounded on all 6 sides by very big PMTs to look for the light produced if any of the protons in that clean water happened to decay. Throughout that experiment, and including some upgrades,  no protons were ever seen to have decayed. But on one particularly cool morning, I went in there (probably hung over) and everyone was loosing their minds.

Professors were actually down in the lab, postdocs and staff scientists were all over the place hunching over displays and pointing and giggling and arguing. As a dumbass undergraduate, I did not know exactly what was going on, but I knew it was exciting to them. Later that day, I accosted one of the staff scientists and said "what the hell?". He showed me a scatter plot (an old school VT100-like lineprinter scatterplot if you can picture that), and in the lower left corner there were 6 or 7 little X's.

Those were neutrinos from SN1987A that underwent charged-current interactions producing leptons which produced light in the water which the PMTs saw.

It was at exactly this point that I realized how truly exciting science can be. As a result, a year or so later, I applied to a summer science program at Brookhaven National Laboratory, and was selected to attend by a new experiment at the Alternating Gradient Synchotron. That was so much fun that I applied to graduate school at Stony Brook a year later (collaborating institution on that same experiment), and to this day (some 25 years later) I am still doing physics at BNL, now at the RHIC collider. So, SN1987A was quite undoubtedly part of the reason why my day job is as a physicist. I love it. Sometimes exciting stuff sneaks up and bites you on the tookus.
Sorry for the tolstoy. I've never typed this out before... cheers
2014-06-25 08:26:34 PM  
1 vote:
Just my two cents, but as a physicist who worked on the Neutrino projects (ICECUBE and AMANDA), the article takes a lot of the right things into account.  The first blind leap of faith I saw was estimating the mass of the galaxy through which they are passing.  That alone puts a big question mark on the resulting calculations.  Another little tweak might come from inflation and expansion.  But I am glad to see the questions are being asked.

Some additional items:  Photon packets may have no mass.  They may not interact with the Higgs field.  However, they do seem to have momentum and are affected by gravity wells.  Momentum and linearity may be more associated with space-time than with mass.  But that is something for someone else to address.

Lastly: There are three types of Neutrinos.  The most interesting ones are WIMPS (weak interactive massive particles).  These are being studied to see if they are responsible for some of the proposed dark matter in the universe.  When one of these massive Tau Neutrinos smacked into our detector, it lit the thing up like a Christmas Tree.  The ones shot out by the sun are relatively small Electron Neutrinos.

I enjoyed the article and all of your comments!
2014-06-25 07:55:23 PM  
1 vote:

dionysusaur: Don't photons have to have _some_ mass in order to transmit/transfer energy?

Surprisingly, no. Well, surprising if you were taught physics the way it's usually taught in school, which is to start with the mechanics of macroscopic objects and everyday experience and appeals to intuition, and to speak of energy as a property of moving bodies.

It turns out, though, that in order to properly grok physics, you have to unlearn that idea and discover that energy can exist and be transferred in lots of ways, of which massive particles moving through space is just one special case. It turns out that fields are what are truly fundamental. One way to think about it is to imagine a field (electromagnetic, gravitational, or otherwise) as a stretched wall-to-wall carpet -- there is energy "stored" in the tension in the carpet. And you can move that energy around by stretching the carpet in one place or another. You can also think of a particle as a bump in the carpet -- a highly localized bit of tension that you can move around, but if you push it down it just pops up elsewhere. Now, if you can imagine that same thing but without the carpet -- like the Cheshire cat disappearing and leaving only its smile, the carpet disappears leaving only the tension -- you are 90% of the way to a good mental picture. (By the way, this analogy is completely wrong in every conceivable physical way, but it gives the right sense).

Perhaps even more counterintuitive is that photons (and other massless particles) also have momentum. This is how a solar sail works: the photons "bounce off" the sail, which rebounds in the opposite direction. Even less intuitively, perhaps, the fields themselves have momentum. Again, this is because momentum is the more fundamental property; the fact that for a macroscopic object with mass, moving at low speed, (momentum = mass x velocity) is just a special case of momentum. A fuller discussion is probably TL;DR for this thread, though.
2014-06-25 04:51:55 PM  
1 vote:
Ehh, space is only a pretty good vacuum, not perfect. Figure an atom of hydrogen per cubic meter, 9.46 *10^15 meters per light year, and 1.68*10^5 light years to the star. Just ballpark, but there's 1.5 *10^21 atoms of hydrogen per square meter between you and that star.
2014-06-25 04:23:04 PM  
1 vote:

BafflerMeal: wjllope: "Neutrinos and photons both travel at the speed of light, "

um, no...


neutrinos have mass. A very small mass, but non-zero. (Just pointing out the usual science-reporting-fail)...cheere
2014-06-25 04:19:40 PM  
1 vote:
"Neutrinos and photons both travel at the speed of light, "

um, no...
2014-06-25 04:05:52 PM  
1 vote:
But the speed of love is still the same right?
2014-06-25 03:56:58 PM  
1 vote:

Considering that the 'speed of light' (IE, the speed of photons) slows down inside a physical medium like,
say, interstellar dust clouds, whereas neutrinos can zip through almost all intervening matter, I don't see
why the theory of relativity needs to be revised in any way.

But I'm not a scientist.
2014-06-25 03:55:56 PM  
1 vote:
We finally discovered that bad news is made out of neutrino particles.
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