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GrahamHill
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Can Neutrinos Go Faster Than Light?

Thu Sep 22, 2011 8:03 pm

Some scientists in Lyon discovered that some particles were travelling faster than the speed of light. Those particles are neutrinos. On their way between France and Italy, they should have done 730 km in at least 2.43 thousands of a second. But they were 60 nanoseconds faster.

The experiment will need to be redone again and again to confirm whether this is correct or not.

However, some scientists already claim it is BS, like Chang Kee Jung, a neutrino physicist at Stony Brook University in New York who says the result is the product of a systematic error.

More here: http://news.sciencemag.org/scienceno...trinos-travel-faster-than-lig.html

I won't go too much into the debate because I simply suck in science, but I would be interested to read your point of view. Do you stand by Einstein's theory and believe those scientists made a mistake, or do you believe it can be plausible to have a particle travelling faster than light?
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san747
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RE: Can Neutrinos Go Faster Than Light?

Thu Sep 22, 2011 8:23 pm

From what I take from the article, that 60 nanosecond figure is the average, with a reported 10 nanosecond uncertainty. Even if that uncertainty figure is not true, GPS signals (which are being used to measure the distances/times) have uncertainties still only in the 10s of nanoseconds.

Even with such margin of error, it appears entirely possible then that SOME (remember, this is an average from thousands of launches) of the neutrinos did travel very slightly faster than light. If such resulted can be affirmed and reproduced in another experiment, it would be one of the most important scientific discoveries in decades!
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Confuscius
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RE: Can Neutrinos Go Faster Than Light?

Thu Sep 22, 2011 8:41 pm

Quoting GrahamHill (Thread starter):
Some scientists in Lyon discovered that some particles were travelling faster than the speed of light.

That's ludicrous speed!
Ain't I a stinker?
 
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Dreadnought
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RE: Can Neutrinos Go Faster Than Light?

Thu Sep 22, 2011 8:43 pm

Warp speed, here we come!

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NoWorries
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 1:43 am

For quite a few years there was debate about whether neutrinos had any mass; massless particles necessarily move at the speed of light. In recent years the latest evidence seems to suggest that neutrinos in fact have a very small mass, which requires that their relative velocity never reach the speed of light (lest they achieve infinite mass). So if this is true, something has to break to allow a massive particle to exceed the speed of light. My bet would be on the systematic error thing -- maybe they forgot to account for the fact that the earth is revolving      .
 
flymia
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 2:07 am

Quoting san747 (Reply 1):
From what I take from the article, that 60 nanosecond figure is the average, with a reported 10 nanosecond uncertainty. Even if that uncertainty figure is not true, GPS signals (which are being used to measure the distances/times) have uncertainties still only in the 10s of nanoseconds.

Exactly what I was thinking. The margin for error still makes it seem that the results could be possible. Should be an interesting few weeks/months while they study this more.

Quoting NoWorries (Reply 4):
My bet would be on the systematic error thing -- maybe they forgot to account for the fact that the earth is revolving

Now that would be something.
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Dreadnought
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 2:49 am

Quoting NoWorries (Reply 4):
maybe they forgot to account for the fact that the earth is revolving

2.43 thousandths of a second = 2,430,000 nanoseconds = the speed of light for that particular distance. 60 nanoseconds would thus equate to a variance of 16,500 miles per hour, at the earth's surface. Circumference of the earth is 24,900 miles. That would indicate that the earth is rotating once every 1.5 hours.

Fun with physics...
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san747
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 6:14 am

Quoting Dreadnought (Reply 6):

Nice job with that analysis! I figured the rotation of the Earth wasn't fast enough to account for the discrepancy.
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Geezer
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 6:56 am

Quoting NoWorries (Reply 4):
maybe they forgot to account for the fact that the earth is revolving

I'll bet I know what caused them to go so fast; it was extremely windy that day........so they had a tail-wind !

( And I'll bet Einstein would agree with me too ! )

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sebolino
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 7:19 am

Quoting GrahamHill (Thread starter):
Do you stand by Einstein's theory and believe those scientists made a mistake, or do you believe it can be plausible to have a particle travelling faster than light?

Actually Einstein didn't say that a particle can't travel faster than light, but that it speed can't be higher than the speed of light (AFAIK).
If the particle actually travel in time, there's no contradiction ...
 
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 7:28 am

Quoting Geezer (Reply 8):
I'll bet I know what caused them to go so fast; it was extremely windy that day........so they had a tail-wind !

( And I'll bet Einstein would agree with me too ! )

Maybe French ATC were on strike, and the airspace was much clearer than average?   
 
MadameConcorde
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 9:20 am

I posted on this on another forum.

I hope time travel will be made possible before I die.

I want to fly on Concorde (again)


        



Tiny Neutrinos May Have Broken Cosmic Speed Limit

http://www.nytimes.com/2011/09/23/science/23speed.html

The physics world is abuzz with news that a group of European physicists plans to announce Friday that it has clocked a burst of subatomic particles known as neutrinos breaking the cosmic speed limit — the speed of light — that was set by Albert Einstein in 1905.

If true, it is a result that would change the world. But that “if” is enormous.
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NoWorries
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 10:26 am

Quoting Dreadnought (Reply 6):
2.43 thousandths of a second = 2,430,000 nanoseconds = the speed of light for that particular distance. 60 nanoseconds would thus equate to a variance of 16,500 miles per hour, at the earth's surface. Circumference of the earth is 24,900 miles. That would indicate that the earth is rotating once every 1.5 hours.


Interesting, I'm actually surprised that it's even in the ballpark of consideration -- 1.5h vs 24h means that it might account for a small part of the difference and would have been corrected for (and I'm sure they would have) -- and that's assuming that the a significant part of the velocity is along a path tangential to the rotation of the earth.

Looks like our best hope now is the tail wind !!!

[Edited 2011-09-23 03:34:29]
 
AustrianZRH
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 11:42 am

Quoting NoWorries (Reply 12):
1.5h vs 24h means that it might account for a small part of the difference and would have been corrected for (and I'm sure they would have)

You don't have to correct for it. The speed of light is independent of the system of reference you are in (a weird byproduct of time dilatation and relativistic length contraction). Actually this speed of the earth was exactly what Michelson and Morley used to empirically corroborate the theory that c is independent of the system of reference.

http://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment
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NoWorries
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 11:53 am

Quoting AustrianZRH (Reply 13):
You don't have to correct for it. The speed of light is independent of the system of reference you are in (a weird byproduct of time dilatation and relativistic length contraction). Actually this speed of the earth was exactly what Michelson and Morley used to empirically corroborate the theory that c is independent of the system of reference.


The speed of light isn't the thing being corrected though, it's the speed of the neutrino relative to the detector that's being corrected. The speed of mass-less particles (e.g. photons of light) always move, well, at the speed of light and have that same speed relative to all observers. Particles with mass: electrons, neutrinos, etc. (at least up 'til now) could have differing relative speeds and therefore the speed of a massive object "depended" on the observer's frame of reference.

That is why, if this is true, it throws a great big monkey-wrench into physics as it's been known for the pat 100+ years.
 
NoWorries
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 12:04 pm

Quoting MadameConcorde (Reply 11):
Tiny Neutrinos May Have Broken Cosmic Speed Limit

http://www.nytimes.com/2011/09/23/sc....html


This is a pretty good synopsis, and it points out that a similar experiment was done at Fermilab a few years back and it's results were consistent with physics -- however the experiment wasn't conducted at the same level of accuracy as this latest experiment.

So they did what all good scientist do -- they publish a paper stating they've observed something that can't be explained using the current laws of physics -- it's an invitation for other scientists to refute or affirm their findings.

I think a lot of scientists are skeptical because 100+ years of experimental results have affirmed the current theories -- of course Newton had been "correct" for over 200 years before Einstein came along in 1905 and said -- "not quite right".
 
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 1:49 pm

The neutrinos took a shortcut through an extra dimension.
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AustrianZRH
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 1:52 pm

Quoting NoWorries (Reply 14):
Particles with mass: electrons, neutrinos, etc. (at least up 'til now) could have differing relative speeds and therefore the speed of a massive object "depended" on the observer's frame of reference.

Now I'm feeling REALLY stupid and think I should consider stopping my PhD      .
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 3:03 pm

Quoting homsar (Reply 16):
The neutrinos took a shortcut through an extra dimension.

That might actually be a realistic possiblity. If there was a small warp in spacetime (like a worm hole or an extra dimentional shift) the nutreno might still be traveling at the speed of light but have only travelled a shorter distance.

Or perhaps they messed up in their observation.

Or perhaps Nutrenos can go faster than light. If they are massless then they really have not broken E=mc2 because their mass would not increase as their speed increases if they are massless.

It's going to be an interesting time trying to see what happened!
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comorin
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 3:40 pm

Quoting NoWorries (Reply 15):

The big relativistic issue here is simultaneity. If a neutrino arrives faster than the speed of light at point A from point B, then it actually left point B earlier than it actually did as per Einstein. 'Now' to me at point A is actually distance/c displaced to a guy at point B.
 
sw733
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 4:14 pm

Quoting GrahamHill (Thread starter):
Do you stand by Einstein's theory

Theories are theories...practice is practice. Einstein could create as many theories as he wanted, but he simply didn't have the means to prove or disprove them. We are starting to have the means now...starting. I see no reason to stick to Einstein's unproven theories when we are starting to see evidence that they might (I stress might...could...maybe) be wrong.

Quoting NoWorries (Reply 4):
In recent years the latest evidence seems to suggest that neutrinos in fact have a very small mass

Yes, that was my understanding

Quoting nighthawk (Reply 10):
Maybe French ATC were on strike, and the airspace was much clearer than average?

If particles went faster every time France was on strike, god knows what we would have proven by now...
 
san747
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 5:23 pm

Quoting sw733 (Reply 20):

Theories are theories...practice is practice. Einstein could create as many theories as he wanted, but he simply didn't have the means to prove or disprove them. We are starting to have the means now...starting. I see no reason to stick to Einstein's unproven theories when we are starting to see evidence that they might (I stress might...could...maybe) be wrong.

Well a theory is the best working explanation for a natural phenomenon we observe. I agree we will have to reconsider Einstein's theories if this is true (and believe me, I'm rooting for it because of the implications should it be true), but I don't think we should abandon those theories until such evidence against them can be corroborated independently.
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iflykpdx
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 6:07 pm

The skeptic in me is leading to the conclusion that the simplest explanation is probably the correct one: They made an error in measurement or calculation, or the instruments malfunctioned or were incorrectly calibrated. A challenge to such a mountain of evidence in favor of relativity has a damn high burden of proof to overcome.
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 6:32 pm

Quoting san747 (Reply 21):
and believe me, I'm rooting for it because of the implications should it be true

What are the implications? In simple English, please  
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 6:45 pm

Quoting DeltaMD90 (Reply 23):

What are the implications? In simple English, please

The implications would be that light speed is not an absolute limit, That something like "warp speed" might actually be theoretically possible.
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DeltaMD90
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 6:47 pm

Quoting Dreadnought (Reply 24):
That something like "warp speed" might actually be theoretically possible.

only if you're a neutrino I guess  
Ironically I have never flown a Delta MD-90 :)
 
sw733
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 6:56 pm

Quoting san747 (Reply 21):
but I don't think we should abandon those theories until such evidence against them can be corroborated independently.

Well of course. But the idea that Einstein's once groundbreaking theory, years and years ahead of its time, could even possibly be proven wrong...wow, science has come a long way!
 
comorin
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 7:28 pm

This discovery, if true, would also stand cause and effect on its head. In the world as we know, cause precedes effect, but at faster than light, effect would precede cause - unless we had a new concept of time. We would be able to send information back in time and change events after they had happened.

That is the real reason this discovery could be revolutionary and Earth-shaking.
 
flybaurlax
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 7:48 pm

It's all very interesting and I'm patiently waiting further news on this. In the meantime, here's a funny comic about it.
http://xkcd.com/955/
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ER757
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 7:58 pm

Quoting comorin (Reply 27):
This discovery, if true, would also stand cause and effect on its head. In the world as we know, cause precedes effect, but at faster than light, effect would precede cause - unless we had a new concept of time. We would be able to send information back in time and change events after they had happened.

That is the real reason this discovery could be revolutionary and Earth-shaking.

That's pretty mind-blowing stuff. But I'm not really sure about how it would work in practice. We might not see the cause before the effect but it would take place just the same, would it not? I'm unclear about how traveling faster than light equals time travel. I get the idea that people standing still will age faster than someone moving faster than light, but that faster than light person isn't actually traveling to the past, his "future" is just taking longer to occur.
I don't know, maybe I've got it all wrong - my degree's in chemistry, not physics.
I do like the idea of the "laws" of physics being challenged though. Something tells me we don't have it all right and calling what we accept "law" is arrogant.
 
comorin
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 11:03 pm

Quoting er757 (Reply 29):

You're right. I once attended a lecture by two Nobel Laureates (Cosmic Background Radiation and Dark Matter) who said that we know nothing of 96% of the universe, so there is a lot to be discovered. Just like when Einstein came along and upended our understanding of the Universe, it's possible that this discovery (if valid) will open up a whole new branch of Physics.

Quoting er757 (Reply 29):
That's pretty mind-blowing stuff. But I'm not really sure about how it would work in practice. We might not see the cause before the effect but it would take place just the same, would it not? I'm unclear about how traveling faster than light equals time travel. I get the idea that people standing still will age faster than someone moving faster than light, but that faster than light person isn't actually traveling to the past, his "future" is just taking longer to occur.

I think NoWorries or other physicists on a.net can explain it a lot more elegantly than I could, but here's a shot:


First, let's talk about the concept of 'Now'. 'Now' relates to this instant here, and to someone a parsec (light-second) away, it would be a second later. So the speed of light (no relationship to what you see) defines simultaenity.

If a neutrino shows up faster than the speed of light, then it is actually showing up faster than the speed of time. So the neutrino was moving and on its way from the emitter even before it was emitted.

The speed of light in vacuum is actually the speed of time. If you travel faster than light, you are in a different 'Now'. You've entered the Past until Time catches up.
 
NoWorries
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 11:44 pm

Quoting AustrianZRH (Reply 17):
Now I'm feeling REALLY stupid and think I should consider stopping my PhD


This stuff is just darn tricky to think about -- so now I'm thinking correction doesn't make sense ...

If I fire a gun from a moving car and observe the muzzle velocity, and then do the same from a stationary car, seems like I should observe the same muzzle velocity (ignoring air resistance). So if the "gun" firing the neutrinos is fixed to the earth and so is the detector, maybe it shouldn't matter if the earth is revolving and there's no need for correction?

But then again, the earth's surface isn't moving linearly, it's accelerating around a circular path -- so maybe we do need correction?

Help, I've fallen and can't get up ...   
 
mffoda
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 11:52 pm

In regards to the title of this topic... This is A-net!

I'm sure the average member should find this an elementary question!  
harder than woodpecker lips...
 
NoWorries
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RE: Can Neutrinos Go Faster Than Light?

Fri Sep 23, 2011 11:59 pm

Quoting comorin (Reply 19):
The big relativistic issue here is simultaneity. If a neutrino arrives faster than the speed of light at point A from point B, then it actually left point B earlier than it actually did as per Einstein. 'Now' to me at point A is actually distance/c displaced to a guy at point B.
Quoting comorin (Reply 27):
This discovery, if true, would also stand cause and effect on its head. In the world as we know, cause precedes effect, but at faster than light, effect would precede cause - unless we had a new concept of time. We would be able to send information back in time and change events after they had happened.

That is the real reason this discovery could be revolutionary and Earth-shaking.

These kinds of thought experiments make my head hurt   

Cause and effect is at the core of classical physics -- on the other hand, quantum physics tosses cause and effect out the window; A third, "new and improved" physcis ?? I'm thinking the odds still favor some sort of error -- but if the result is valid, the next question is how much tweaking is needed to classical and quantum physics to "save" them?
 
vikkyvik
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RE: Can Neutrinos Go Faster Than Light?

Sat Sep 24, 2011 12:10 am

Quoting comorin (Reply 30):
parsec (light-second)

Not to be picky, but a parsec isn't a light-second (at least not in the same way as a light-year).

Indeed, a parsec is much larger than a light-year. It's the distance at which one AU (astronomical unit ~93,000,000 miles) covers 1 arc-second (1/3600 of a degree). So think of a right triangle, of which one angle is 1 arc-second, the short leg is 1 AU, and the long leg is 1 parsec. Works out to 3.26 light-years.

Unless you're in Star Wars, timing a ship making the Kessel Run.  
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comorin
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RE: Can Neutrinos Go Faster Than Light?

Sat Sep 24, 2011 12:34 am

Quoting vikkyvik (Reply 34):
uoting comorin (Reply 30):
parsec (light-second)

Not to be picky, but a parsec isn't a light-second (at least not in the same way as a light-year).

Sorry about that, that's a big boo-boo!   I should stick to the troll threads....
 
Pyrex
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RE: Can Neutrinos Go Faster Than Light?

Sat Sep 24, 2011 3:14 am

Quoting GrahamHill (Thread starter):
Some scientists in Lyon discovered that some particles were travelling faster than the speed of light. Those particles are neutrinos. On their way between France and Italy, they should have done 730 km in at least 2.43 thousands of a second. But they were 60 nanoseconds faster.

The funny thing is, they were still overtaken by some Italian drivers on their way back home. 
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Airstud
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RE: Can Neutrinos Go Faster Than Light?

Sat Sep 24, 2011 7:41 am

Neutrino.

Who's there?

Knock knock.
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san747
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RE: Can Neutrinos Go Faster Than Light?

Sat Sep 24, 2011 8:59 am

Quoting sw733 (Reply 26):

Well of course. But the idea that Einstein's once groundbreaking theory, years and years ahead of its time, could even possibly be proven wrong...wow, science has come a long way!

Oh absolutely. I love that we're in a position to make all these new discoveries. Science is all about updating our information and explanations for what we observe, and this is another great example!

Quoting comorin (Reply 30):

The speed of light in vacuum is actually the speed of time. If you travel faster than light, you are in a different 'Now'. You've entered the Past until Time catches up.

I comprehend what you're saying, but I'm still trying to wrap my brain around how that puts you in the past. I understand at the speed of light, time no longer advances forward- a particle traveling at that speed is ageless because no time has passed from its perspective, even if it's been traveling for 3 billion years. So if I go faster than the speed of light, don't I just get to the future faster?

I guess... does time dilation end at the speed of light, or can time dilate further past that speed?
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NoWorries
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RE: Can Neutrinos Go Faster Than Light?

Sat Sep 24, 2011 12:27 pm

Quoting san747 (Reply 38):
I guess... does time dilation end at the speed of light, or can time dilate further past that speed?


Part of the problem is our ability to define space and time. Classical and quantum physics, for example, have somewhat differing views.

Classical physics (in the form of General Relativity) asserts that space and time are emergent properties -- in any location they are essentially defined by a particular distribution of mass/energy. As a consequence, every "point" in space/time has it's own set of rulers and clocks for measuring space and time. It's not as if the past or present actually exists somewhere and you can go to it -- space and time are an ever-evolving set of relationships.

Quantum physics treats space and time as a fixed background in which events occur. What's interesting is that in the quantum world time is largely reversible -- particles have no qualms about moving backwards or forwards in time on the fixed background. In fact, a positron (anti-electron) moving forward in time is indistinguishable from an electron moving backward in time. There is a certain amplitude for a particle to move backward in time, but for some reason when all of the various amplitudes add up, the aggregate behavior for particles is to move forward in time and results in a preferred direction for the arrow of time.

This conflicting view of space and time may mean that neither approach (classical or quantum) is completely correct.
 
AustrianZRH
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 7:55 am

Quoting NoWorries (Reply 31):
If I fire a gun from a moving car and observe the muzzle velocity, and then do the same from a stationary car, seems like I should observe the same muzzle velocity (ignoring air resistance).

No, that's the easy classic stuff. If you fire a Steyr AUG from a car moving at 30 m/s and measure the muzzle velocity sitting in the car relative to the car, you will come up with 990 m/s. If you sit at the side of the road and measure the muzzle velocity relative to the road, you will come up with 1020 m/s. That's all non-relativistic stuff and easy to compensate.

With the neutrinos it's the same: your source and your detector both sit on the Earth's surface and thus move at the same velocity - it's like when you're sitting in your car and measuring in your car. And as all speeds are related to c and c is constant in all reference systems it shouldn't matter anyway (relativity - what's the fixed point? - you can easily say Earth is fixed and everything else moves relative to the Earth, just as you could use a point halfway to Alpha Centauri as your fixed point). By the way, the revolution speed of the earth is about 0.994E-4*c compared to the center of gravity of the solar system. The deviation measured is 30% higher, at 1.395E-4*c!

But relativity is killing me anyway, so I should stop thinking now I guess, maybe I'm writing c..p  .
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DeltaMD90
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 3:40 pm

Where did all you a.netters learn your physics stuff? Is there a website that breaks it down and takes you from square 1? It really interests me and I'm able to comprehend concepts well, I just need it from the beginning...
Ironically I have never flown a Delta MD-90 :)
 
san747
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 7:47 pm

Quoting DeltaMD90 (Reply 41):
Where did all you a.netters learn your physics stuff? Is there a website that breaks it down and takes you from square 1? It really interests me and I'm able to comprehend concepts well, I just need it from the beginning...

This is a good starting point, covers all the ideas of special relativity well without getting too technical and confusing:

http://en.wikipedia.org/wiki/Introduction_to_special_relativity
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 10:22 pm

Quoting AustrianZRH (Reply 40):
No, that's the easy classic stuff. If you fire a Steyr AUG from a car moving at 30 m/s and measure the muzzle velocity sitting in the car relative to the car, you will come up with 990 m/s. If you sit at the side of the road and measure the muzzle velocity relative to the road, you will come up with 1020 m/s. That's all non-relativistic stuff and easy to compensate.

I don't think I stated that very well ... measuring velocity from the car perspective of a round fired from the car is the same as measuring velocity from the groud perspective of a round fired from the ground. So for the linear case there is no need for correction (due to the motion of the earth), which I think is the same as what you're saying -- which also repudiates my original thought that correction was needed.
 
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 10:28 pm

Quoting DeltaMD90 (Reply 41):
Where did all you a.netters learn your physics stuff? Is there a website that breaks it down and takes you from square 1? It really interests me and I'm able to comprehend concepts well, I just need it from the beginning...

Before delving into relativity or quantum, it's a good idea to have a good grounding in classical dynamics -- understand the difference between scalars and vectors; understand mass, velocity, acceleration, force, work/energy, etc. Let me dig around a bit ,,,
 
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Dreadnought
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 10:36 pm

Quoting AustrianZRH (Reply 40):
No, that's the easy classic stuff. If you fire a Steyr AUG from a car moving at 30 m/s and measure the muzzle velocity sitting in the car relative to the car, you will come up with 990 m/s. If you sit at the side of the road and measure the muzzle velocity relative to the road, you will come up with 1020 m/s. That's all non-relativistic stuff and easy to compensate.

Does that apply to light? Speed of light is 186,000 miles per second. If you put a flashlight on the nose of a rocket travelling at 100,000 miles per second, will the light traveling from the flashlight be going 286,000 miles per second, relative to a fixed point in space? I don't think so. I expect light acts similarly to sound waves. If you could travel (silently) at Mach 2, and 100 yards behind you you had a very loud F-15 traveling at the same speed, you shouldn't be able to hear him.
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san747
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 10:43 pm

Quoting Dreadnought (Reply 45):
If you put a flashlight on the nose of a rocket travelling at 100,000 miles per second, will the light traveling from the flashlight be going 286,000 miles per second, relative to a fixed point in space? I don't think so.

Correct. The speed of light is always the same value of ~186,000 miles/second no matter your speed or relative position compared to the light.
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 11:17 pm

Quoting Dreadnought (Reply 45):

Does that apply to light? Speed of light is 186,000 miles per second. If you put a flashlight on the nose of a rocket travelling at 100,000 miles per second, will the light traveling from the flashlight be going 286,000 miles per second, relative to a fixed point in space? I don't think so. I expect light acts similarly to sound waves. If you could travel (silently) at Mach 2, and 100 yards behind you you had a very loud F-15 traveling at the same speed, you shouldn't be able to hear him.

The speed of light is constant in all frames of reference -- though the frequency shifts higher or lower depending on whether the observer is traveling towards or away from the source.

What's confounding here is a particle (with mass, no less) traveling faster than light -- it's not clear whether this particle should be light-like (have the same speed in all frames of reference) or be mass-like, have velocities that add by the rules of relative velocity addition. I haven't read anything that addresses the issue -- I'm assuming because physicists haven't spent too much time thinking about particles that move faster than light?

Just as an aside, this discussion is in the context of a vacuum -- it is possible for objects to move faster than light through a medium -- for example Cherenkov radiation http://en.wikipedia.org/wiki/Cherenkov_radiation

But in this case, they're not moving faster than light moves in a vacuum, only faster than light moves in the medium.

[Edited 2011-09-26 16:50:08]
 
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RE: Can Neutrinos Go Faster Than Light?

Mon Sep 26, 2011 11:46 pm

Quoting DeltaMD90 (Reply 41):
Where did all you a.netters learn your physics stuff? Is there a website that breaks it down and takes you from square 1? It really interests me and I'm able to comprehend concepts well, I just need it from the beginning...

An oldie but a goodie is http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
This isn't really a tutorial, but a nice frame of reference in which to explore -- almost every topic hits the high points. Start exploring a particular topic by gathering some general ideas and then develop the ideas using web searches and published references. What I've found (at least in my own case) is the need to deeply internalize an idea in order to be able to work with it easily. This can be rather time-consuming -- I don't know of any quick reads. Research geared towards understanding a particular problem -- for example this thread -- is a great way to build up an understanding (necessity is the mother of invention).

Einstein for Dummies is a nice into to special and general relativity.

I think Quantum World by Kenneth Ford is one of the better intros to quantum physics.

QED by Richard Feynman is an interesting read, Feynman supposedly quipped that someone can learn Quantum Field Theory by spending five years in graduate school -- or by reading his book. It's a short book written using very plain language -- and it has to be read very very carefully.

[Edited 2011-09-26 16:52:00] having real typing problems today

[Edited 2011-09-26 16:52:43]
 
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hOMSaR
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RE: Can Neutrinos Go Faster Than Light?

Tue Sep 27, 2011 1:43 am

Old news. This kid already figured out that the cosmic speed limit was faster than the speed of light:

http://www.indystar.com/apps/pbcs.dll/article?AID=2011103200369

Unfortunately, the Youtube video (where he made the claim) is no longer active.

Now, on the other hand, the real question is, can anything move faster than the speed of love?

http://familyguy.wikia.com/wiki/Faster_Than_the_Speed_of_Love
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