[Mbodell]

 BunnyGo, on 2011-November-18, 11:26, said:

One question for the physicists (or physics knowledgeable people). If the neutrinos really are going faster than light, shouldn't they arrive before they are produced? Or is the theory that relativity is completely wrong with regards to faster than light travel and its effects?

My non-expert physics answer is: It depends on your frame of reference. From the frame of reference of where they arrive you'd see them arrive and then you'd see the light from where they were created later. From an external frame of reference roughly equally distant from the start and end of the path, you'd see them where they started. So faster than light doesn't necessarily mean backwards in time in the linear way some folks expect.

[barmar]

 BunnyGo, on 2011-November-18, 11:26, said:

One question for the physicists (or physics knowledgeable people). If the neutrinos really are going faster than light, shouldn't they arrive before they are produced? Or is the theory that relativity is completely wrong with regards to faster than light travel and its effects?

If that part of the theory is correct, I think it states that time should go backward in the frame of reference of the neutrinos. That's not the same as the frame of reference of the observers measuring the departure and arrival times from their labs.

Unfortunately, neutrinos have neither wrists nor pockets, so there's nowhere to put a watch on them to see what's happening in their time.

But in any case, if Einstein was wrong about the speed of light being a fundamental limit, it throws into question all the conclusions that come from it, including time dilation.

[BunnyGo]

 barmar, on 2011-November-18, 21:36, said:

But in any case, if Einstein was wrong about the speed of light being a fundamental limit, it throws into question all the conclusions that come from it, including time dilation.

Time dilation from (both special and general) relativity has been confirmed in lots of experiments (including every time someone uses GPS). I'm not so worried that what happens in most observable relativistic effects is wrong, it's this possible faster than c speeds that are weird.

[shyams]

 S2000magic, on 2011-November-18, 11:34, said:

Not the way it's written; if it had said that the odds against Einstein being wrong had shrunk, it would mean that it's less likely that he was wrong.

The opposite. It is more likely now that Einstein was wrong.

When odds shorten, the probability increases

[nige1]

Our Physics teacher said:

There was a young lady named Bright
Who travelled much faster than light.
She departed one day
In a relative way
And returned the previous night.

There was a young fellow named Fisk
At fencing exceedingly brisk.
So fast was his action,
The Fitzgerald contraction
Reduced his rapier to a disk.

[gwnn]

Bernoulli's equation has always been my favourite in Physics, but especially after I've heard this song:

 Superb Calculation of the Pressure in a Fluid

new words by R. M. Panoff

Tune: Supercalifragilisticexpialidocious

Bernoulli knew he had a rule he used for wings in air
For fluids incompressible he'd never have a scare.
The density of energy's the same at every spot
A caveat is cavitation in which case it's not!

	Oh, Superb calculation of the pressure in a fluid
	Is simple so that anyone with any sense can do it.
	We all deserve a force conserved among the objects paired.
	Just add to pressure rho gee aitch then add half rho vee squared

A water tower tower's o'er a town so water goes
Through every pipe, and when you turn the faucet on it flows.
The pressure head is now instead a steady stream, you see,
The pipe's diameter determines stream velocity.

The sum at every point's a constant, check it if you care
Each term can change within a range for water or for air.
The key's to keep the units straight and don't have any gap
Or else your fluid starts to leak and then you'll just get Oh....

[barmar]

 BunnyGo, on 2011-November-18, 10:37, said:

I'd still back Einstein (as per several XKCD strips) but apparently the experiment has been repeated.

Oh, and doesn't

"The odds have shrunk that Einstein was wrong about a fundamental law of the Universe"

mean that it's less likely that Einstein was wrong? Why put a sentence like that in front of an article describing how an experiment "showing" he was wrong has been repeated?

Where did you see that line? The first of the article is "The chances have risen that Einstein was wrong about a fundamental law of the universe."

[gwnn]

I guess they changed the article. It did start with "the odds have shrunk".

[BunnyGo]

Interesting, I guess an editor (or the author) didn't like that line either.

[whereagles]

 JLOGIC, on 2011-September-22, 21:55, said:

I can't wait to travel back in time, it's only a matter of time... or is it?

Probably not. A series of people (myself included) have given evidence for the impossibility of time-travelling into the past. You can time-travel into the future, but into the past is a whole other ball game.

In case you're wondering, to travel into the future you "just" hop on a spaceship, accelerate close to the speed of light and spin around a bit. When you're back, there will be more time enlapsed on Earth than in the spaceship, so you effectively travelled into the future.

[whereagles]

 BunnyGo, on 2011-November-18, 11:26, said:

One question for the physicists (or physics knowledgeable people). If the neutrinos really are going faster than light, shouldn't they arrive before they are produced? Or is the theory that relativity is completely wrong with regards to faster than light travel and its effects?

Faster than light neutrinos would make them what physicists call 'tachyons'. Such objects appear in some theories (e.g. string theory) and they cause a couple of phenomenological problems, so people usually tweak the theories to get rid of them.

There are a lot of funny things you can do with tachyons, but in short this is what it boils down to: we'd have a lot of stuff to rewrite if this FTL neutrinos thing were true.

[blackshoe]

Niven's Law of Time Travel: In any Universe of discourse in which time travel is possible, it will not happen.

[mwalimu02]

interesting!

[BunnyGo]

True? False? Still taking all bets!

[PassedOut]

Neutrinos clocked at light-speed in new Icarus test

Quote

An experiment to repeat a test of the speed of subatomic particles known as neutrinos has found that they do not travel faster than light.

But they do travel pretty fast anyway...

[kenrexford]

I have absolutely no knowledge of anything going on here with neutrinos. That said, the reason for my post is that my reaction to the "news" about neutrinos was, "That's old stuff."

I mean, I recall hearing back in the mid-1980's that Einstein might be wrong and that neutrinos went faster than the speed of light. If I recall correctly, the reason back then was something about being able to detect a surge in neutrinos before the light reached us when a star went nova, or something. Of course, that probably had some other explanation for some, but the point was that the neutrinos-go-too-fast scenario seems to have been around for a while, hasn't it?

[USViking]

 kenrexford, on 2012-March-16, 09:59, said:

I have absolutely no knowledge of anything going on here with neutrinos. That said, the reason for my post is that my reaction to the "news" about neutrinos was, "That's old stuff."

I mean, I recall hearing back in the mid-1980's that Einstein might be wrong and that neutrinos went faster than the speed of light. If I recall correctly, the reason back then was something about being able to detect a surge in neutrinos before the light reached us when a star went nova, or something. Of course, that probably had some other explanation for some, but the point was that the neutrinos-go-too-fast scenario seems to have been around for a while, hasn't it?

Without looking it up IIRC neutrinos began to be ejected in the earliest stages of the supernova process
before light. IOW the earliest surge of neutrinos had enough of a headstart on the light to arrive on Earth
sooner than the earliest surge of light.

[kenrexford]

 USViking, on 2012-March-16, 10:50, said:

Without looking it up IIRC neutrinos began to be ejected in the earliest stages of the supernova process
before light. IOW the earliest surge of neutrinos had enough of a headstart on the light to arrive on Earth
sooner than the earliest surge of light.

Again, speaking from ignorance, but it seems to me that perhaps the explanation offered in the past might have been based upon an assumption that neutrinos could not actually move faster than the speed of light.

In other words, if I assume that x and y must travel at the same speed, and x gets here first, then I must assume that x left first. However, if I assume that x and y do not have to travel at the same speed, then if x gets here first, from a common source and event, I might then assume that x was faster than y. Or, that x took a different route to me.

[USViking]

It turns out the neutrino is a subject fit for poetry:

Cosmic Gall

-John Updike-

Neutrinos, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids through a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold-shoulder steel and sounding brass,
Insult the stallion in his stall,
And scorning barriers of class,
Infiltrate you and me! Like tall
And painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
And pierce the lover and his lass
From underneath the bed-you call
It wonderful; I call it crass.

YOU are now being invaded by about 1014 neutrinos each second!

(although it has turned out they do have mass)

[kenrexford]

 USViking, on 2012-March-16, 10:59, said:

It turns out the neutrino is a subject fit for poetry:

Cosmic Gall

-John Updike-

Neutrinos, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids through a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold-shoulder steel and sounding brass,
Insult the stallion in his stall,
And scorning barriers of class,
Infiltrate you and me! Like tall
And painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
And pierce the lover and his lass
From underneath the bed-you call
It wonderful; I call it crass.

YOU are now being invaded by about 1014 neutrinos each second!

(although it has turned out they do have mass)

Rick Santorum is not going to be happy about this one bit.