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irreversible

Possible neutrinos travel faster than light

52 posts in this topic

[quote name='irreversible' timestamp='1317052673' post='4866103']
[color="#1c2837"][size="2"]it might be an interesting dabble into science fiction to open another topic and try and fantasize what the arrow of time actually is and why we perceive it the way we do. Because I don't believe anyone really has an idea.[/size][/color]
[/quote]

I was under the impression that the 'arrow of time' was simply entropic decay, leading the universe to move from one state to another (order to disorder if memory serves). So given two space-time reference points one in the past (A) and one in the future (B) to go from B to A would require that you could get back to the state the universe was in at point A, which I'm pretty sure is covered as a 'no go' in at least one 'law' (Thermodynamics springs to mind, but dont' quote me, I'm going on half remembered stuff). Or to put it another way; at 4:08pm I break an egg, any attempts at time travel to 4:07pm would require going back to a point where the egg was no longer broken.

IF this is proven correct and IF we can make use of it the only real use I can see is FTL communication. Now, with respect to light speed this is a form of time travel, in that information could make it from one location to another before light (to use the sci-fi example you'll be able to see the enemy fire his laser slightly before it starts trying to remove your hull) but it only remains 'time travel' in that sense.

To give a poor example;
Two space ships are 5 light seconds apart with clocks which are syncronised; at 10seconds past the minute space ship one fires a laser beam at spaceship two, 15 second past the minute space ship two is hit, 20 seconds past the minute spaceship one sees the hit.

With FTL vision when spaceship one fires spaceship two might see the beam coming at 13 seconds past the minute but he still didn't see the event before it happened. Spaceship one would see the 'hit' at 18 seconds past the minute as the event didn't happen until 15seconds past the minute.

The only way this could result in time travel is if Spaceship two saw the laser coming BEFORE 10 seconds past the minute, in other words before the event happened.

So, in short; while I'm no top physicist I'm pretty sure that we are safe from time traveling robots from the future bent on trying to kill people named Connor for a while yet ;)
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[quote name='Discount_Flunky' timestamp='1317076118' post='4866247']
For instance many scientists are starting to find proof that humans have a sixth sense.
[/quote]

Can has links?
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[quote name='phantom' timestamp='1317078558' post='4866257']
[quote name='Discount_Flunky' timestamp='1317076118' post='4866247']
For instance many scientists are starting to find proof that humans have a sixth sense.
[/quote]

Can has links?
[/quote]

[url="http://noosphere.princeton.edu/"]http://noosphere.princeton.edu/[/url]

[url="http://en.wikipedia.org/wiki/Rupert_Sheldrake"]http://en.wikipedia.org/wiki/Rupert_Sheldrake[/url]

These are some I could find. It's really hard to get links about scientific developments when you don't know the name of the experiment or the names of the scientist evolved
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I don't think this has been pointed out before: the observation of the 1987a supernova suggests very strongly that neutrinos travel at exactly the speed of light to very large precision. So this new observation should be taken with a lot of salt.
[url="http://scienceblogs.com/startswithabang/2011/09/this_extraordinary_claim_requi.php"]http://scienceblogs....claim_requi.php[/url]
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[quote name='phantom' timestamp='1317078464' post='4866254']
[quote name='irreversible' timestamp='1317052673' post='4866103']
[color="#1c2837"][size="2"]it might be an interesting dabble into science fiction to open another topic and try and fantasize what the arrow of time actually is and why we perceive it the way we do. Because I don't believe anyone really has an idea.[/size][/color]
[/quote]

I was under the impression that the 'arrow of time' was simply entropic decay, leading the universe to move from one state to another (order to disorder if memory serves). So given two space-time reference points one in the past (A) and one in the future (B) to go from B to A would require that you could get back to the state the universe was in at point A, which I'm pretty sure is covered as a 'no go' in at least one 'law' (Thermodynamics springs to mind, but dont' quote me, I'm going on half remembered stuff). Or to put it another way; at 4:08pm I break an egg, any attempts at time travel to 4:07pm would require going back to a point where the egg was no longer broken.
[/quote]

This really is an interesting topic and my post will quickly spiral out of control, but that's only because there's no real answer to this question.

First off, allow me to make a small correction to the terminology you used: since entropy is a measure of disorder and the universe started out in a state of almost perfect order, then entropy is necessarily growing, not decaying :). But that's that.


Strangely enough entropic growth cannot be proven to be the cause of the arrow of time as it would actually create a causal loop: entropy cannot grow without time. Unless your example regarding the broken egg is a coincidence, it seems you're familiar with Brian Greene's The Fabric Of Cosmos (if you're not, then he discusses the arrow of time very thoroughly - it's quite an exhilarating read). While his argumentation largely explains that since pretty much all of physics (with the exception of some negligible effects from the weak force) is time-invariant (in other words the laws of physics do not forbid time to run in reverse, causing the egg to unshatter), there is no apparent reason for entropy to grow.

It might seem logical that a uniform mist of particles that contains impurities has the potential for entropic growth, but that doesn't quite explain why a) the universe couldn't be experiencing decreasing entropy instead (actually the answer to this would be negative gravity and the reversal of all other forces in nature) and b) why the two would be linked (at this time the cyclic universe is no longer considered a viable option due to its rate of expansion, but a cyclic universe would actually have required the reversal of time to achieve the big crunch). A better answer could be to interpret time as a potential of entropic growth, but again there's no proof of this anywhere other than the fact that the properties of forces cause it to go down this route.

Consider another example that stems from the bubble multiverse theory: "infinite time on the outside equals infinite space on the inside" (this is why a bubble universe might seem infinite on the inside, but is finite on the outside). This in turn brings up two problems to which there are currently no solutions: a) (our) mathematics doesn't have a branch that can reliably handle infinities meaning that we cannot explain how something that has no beginning and no end can flow from one to the and b) and logically, if an increase in entropy is a causal property (not a side effect) of time and there's a finite amount of matter/energy (either in the universe or the multiverse), then at one point you'll still reach the Russian doll situation where you need to explain the starting state of the universe/multiverse and will eventually run out of time as entropy reaches a maximum.

This is all bollocks, though as the ugly truth behind it is that time is a quality/dimension/phenomenon/river we simply do not understand.

As a small thinking exercise consider a simulated universe (khm, a computer game) where, at each iteration, you increase all values by a certain (fixed) amount. This amount doesn't even need to be based on time in our universe - it just happens at every iteration. This means that to the characters in the game time would seem to be flowing at a constant rate. The questions to answer are:

1) why are you [i]increasing (not decreasing or randomizing) [/i]all the values at each iteration?
2) would your game character ever hope to understand your nature or your motives?
3) this one is also from Brian Greene: can you yourself imagine a universe without space and time?
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[quote name='Discount_Flunky' timestamp='1317076118' post='4866247']
[quote name='Eelco' timestamp='1317063684' post='4866176']
[quote name='Discount_Flunky' timestamp='1317054850' post='4866119']
[quote name='Eelco' timestamp='1317046265' post='4866066']
snip[/quote]

What are you talking about the theory of relatively does talk about time and therefore time travel. According to the theory of relatively the faster something travels the slower time passes for that object. Also the higher the gravity around an object the slower time passes for it. Therefore if you travel faster than the speed of light, according to the equation, you would go backwards in time. The notion of time travel was originally proposed by scientist studying relatively, not science fiction writers.
[/quote]

O RLLY?

Indeed, more velocity means slower passing of time; but clearly the geometry of the equation doesnt allow for the extrapolation you posit here, since time dilation as a function of v isnt even differentiable at v==c; it has an infinite slope. The correct extrapolation of ever more velocity isnt into negative time; the correct extrapolation is that the function doesnt extend into the v>c domain at all cause it completely curves away from that domain and doesnt point toward it at all.

Try and plug v > c into the formula for time dilation; you dont get a negative number as your naive extrapolation would have, but an imaginary one. An imaginary flow of time... indeed a concept more apt for science fiction writers than scientists. (or perhaps scientists looking to pry funding loose from people who never looked at the math themselves)
[/quote]

When you put v = c you get 0 which means times stops for the object. The thing is though that getting anything to go the speed of light that has mass takes infinite energy, because things also get more massive the faster they go. According to the equation mass is infinite at the speed of light therefore the energy needed to go faster then the speed of light is impossible to reach. That is way the possibility of Neutrioes going faster then light is so freaky, because that implies that there is a loop hole in relativity.
[/quote]
Light doesnt have a special role in relativity per se. If the neutrinos would go faster than the 'maximum' speed posited by relativity, yes, that would be freaky. Going faster than light should more likely be taken as light not reaching that maximum.

[quote]When most scientist speak of time travel mostly they speak of using something like a black hole's gravity field to make yourself live way longer then you normally would so that you can see the future.[/quote]
Sure, thats perfectly valid, but im not sure id call it time travel.

[quote]The only way to got to the past would be a worm hole, and those haven't been proven yet. Also you could only go back to the time that the worm hole was created.[/quote]Not only have they 'not been proven yet', 'they' are complete theoretical speculation; and not even theoretically sound. Nontrivial space topologies are entirely logically sound notions, but have never been observed; and to extrapolate from that to nontrivial spacetime topologies is just to assume time travel could exist using fancy words; without doing anything to solve the logical contradictions inherent in the notion, by the way.


[quote]Edit: Also just because something sounds far fetched it doesn't mean it's form or should only be mentioned in science fiction. There's a lot crazy science out there. For instance many scientists are starting to find proof that humans have a sixth sense.
[/quote]
Yes, absence of proof is not proof of absence; but thats truely the only thing time travel has going for it. There are no hints or clues it could be possible in our current understanding at all; all people have done is tried to explore what would happen if you forced it into existing theoretical frameworks; and invariably ran into complete nonsense rather than an interesting new experiment to perform.
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[quote name='Prefect' timestamp='1317101918' post='4866320']
I don't think this has been pointed out before: the observation of the 1987a supernova suggests very strongly that neutrinos travel at exactly the speed of light to very large precision. So this new observation should be taken with a lot of salt.
[url="http://scienceblogs.com/startswithabang/2011/09/this_extraordinary_claim_requi.php"]http://scienceblogs....claim_requi.php[/url]
[/quote]

Well; the neutrinos did in fact come three hours earlier; a fact that we managed to rationalize by our model of how light escapes from the core; but then again, how much do we really know about that? Three hours is still very small relative to the OPERA findings, but to use the word 'exactly' seems unwarranted; I think there is a large margin of error here.

Besides, the neutrinos from OPERA are far higher energy, and the particles from the supernova have been moving through a medium which is rather different from our terrestial one, which might matter in some yet to be determined way.

That said, this is the main reason that makes me suspect that what we are to get from all this is a more accurate GPS system, not new physics.
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@Eelco

You talk to me like I'm a third grade boy vainly hoping that time travels exists so I can go back and see Charlemagne or something. Many high profile scientist have put there entire careers into the theory of time travel. It IS A POSSIBILITY using today concepts of science. It's it partially feasible? I really doubt it, but it is theoretically possible. If you aren't read up on the latest theories of time travel then you can't really call yourself a science fan. The truth is stranger then fiction, that's a fact that has been proven time and time again. There are scientist who state that you can create a new universe using giant lasers for crying out loud. Science fiction has nothing on real science.
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[quote name='phantom' timestamp='1317078464' post='4866254']
IF this is proven correct and IF we can make use of it the only real use I can see is FTL communication. Now, with respect to light speed this is a form of time travel, in that information could make it from one location to another before light (to use the sci-fi example you'll be able to see the enemy fire his laser slightly before it starts trying to remove your hull) but it only remains 'time travel' in that sense.
[/quote]
I think it is quite well established, that there is no actual difference between "communication" and "effect". Thus if any information can be transmitted FTL, true time travel is also (theoretically) possible.

This also would make type 2 perpetum mobile possible, as you could use the information abut future state to influence current state, thus always choosing the state, that will result in minimal future enthropy.
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[quote name='Discount_Flunky' timestamp='1317112678' post='4866354']Science fiction has nothing on real science.[/quote]Seeing that the purpose of science fiction is to explore via literature the consequence of invention, it shouldn't.
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[quote name='Eelco' timestamp='1317063684' post='4866176']
[quote name='Discount_Flunky' timestamp='1317054850' post='4866119']
[quote name='Eelco' timestamp='1317046265' post='4866066']
snip[/quote]

What are you talking about the theory of relatively does talk about time and therefore time travel. According to the theory of relatively the faster something travels the slower time passes for that object. Also the higher the gravity around an object the slower time passes for it. Therefore if you travel faster than the speed of light, according to the equation, you would go backwards in time. The notion of time travel was originally proposed by scientist studying relatively, not science fiction writers.
[/quote]
O RLLY?

Indeed, more velocity means slower passing of time; but clearly the geometry of the equation doesnt allow for the extrapolation you posit here, since time dilation as a function of v isnt even differentiable at v==c; it has an infinite slope. The correct extrapolation of ever more velocity isnt into negative time; the correct extrapolation is that the function doesnt extend into the v>c domain at all cause it completely curves away from that domain and doesnt point toward it at all.
[/quote]
FTL travel indeed would make traveling backwards in time possible, but not because of some naive interpolation of equations.


According to the theory of relativity, if two space-time points A & B are separated by space-like distance (i.e. light cannot travel from A to B before B takes place and vice versa), the time-order of those events is not definable. I.e. there are always some reference frames, where A happens before B and some where B happens before A.

Now, if somehow something travels from A to B FTL and reaches the spatial location of B "at or before" B takes place, then in those reference frames where B takes place BEFORE A, it has traveled backwards in time.

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[quote name='Lauris Kaplinski' timestamp='1317117506' post='4866373']
[quote name='Eelco' timestamp='1317063684' post='4866176']
[quote name='Discount_Flunky' timestamp='1317054850' post='4866119']
[quote name='Eelco' timestamp='1317046265' post='4866066']
snip[/quote]

What are you talking about the theory of relatively does talk about time and therefore time travel. According to the theory of relatively the faster something travels the slower time passes for that object. Also the higher the gravity around an object the slower time passes for it. Therefore if you travel faster than the speed of light, according to the equation, you would go backwards in time. The notion of time travel was originally proposed by scientist studying relatively, not science fiction writers.
[/quote]
O RLLY?

Indeed, more velocity means slower passing of time; but clearly the geometry of the equation doesnt allow for the extrapolation you posit here, since time dilation as a function of v isnt even differentiable at v==c; it has an infinite slope. The correct extrapolation of ever more velocity isnt into negative time; the correct extrapolation is that the function doesnt extend into the v>c domain at all cause it completely curves away from that domain and doesnt point toward it at all.
[/quote]
FTL travel indeed would make traveling backwards in time possible, but not because of some naive interpolation of equations.


According to the theory of relativity, if two space-time points A & B are separated by space-like distance (i.e. light cannot travel from A to B before B takes place and vice versa), the time-order of those events is not definable. I.e. there are always some reference frames, where A happens before B and some where B happens before A.

Now, if somehow something travels from A to B FTL and reaches the spatial location of B "at or before" B takes place, then in those reference frames where B takes place BEFORE A, it has traveled backwards in time.
[/quote]
What do you mean, 'has travelled backwards in time'? Indeed, faster than light travel would play funny tricks with our perceptions of causality, but not with causality itself. Yes, if you go faster than light, people get to see your present state before ever getting to see your past states. You can do essentially the same thing with a good old mirror.


Of course these mere perceptions tell us nothing about the interesting question, as to how such a superluminal actor would experience time; how fast or in what manner his elementary particles would jiggle relative to eachother. He isnt going to kill his great gandfather, thats for sure, and as for what would happen to himself, our theory is entirely silent on the matter, unless you can give an interpretation to the passing of imaginary time.
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[quote name='Eelco' timestamp='1317129793' post='4866426']
[quote name='Lauris Kaplinski' timestamp='1317117506' post='4866373']
FTL travel indeed would make traveling backwards in time possible, but not because of some naive interpolation of equations.

According to the theory of relativity, if two space-time points A & B are separated by space-like distance (i.e. light cannot travel from A to B before B takes place and vice versa), the time-order of those events is not definable. I.e. there are always some reference frames, where A happens before B and some where B happens before A.

Now, if somehow something travels from A to B FTL and reaches the spatial location of B "at or before" B takes place, then in those reference frames where B takes place BEFORE A, it has traveled backwards in time.
[/quote]
What do you mean, 'has travelled backwards in time'? Indeed, faster than light travel would play funny tricks with our perceptions of causality, but not with causality itself. Yes, if you go faster than light, people get to see your present state before ever getting to see your past states. You can do essentially the same thing with a good old mirror.
[/quote]
According to the theory of relativity there is NO preferred reference frame - thus the descriptions of reality from all inertial reference frames are equally true.
As I gave in above example - for space-like events in space-time there are no fixed (true) order of precedence. If events A and B are separated by space-like distance, then always for some inertial reference frame (let's call it frameX) event A happens before event B, for some other frame (let's call it frameY) event B happens before event A (and, of course for some frames they are synchronous). And all these descriptions are equally true descriptions of the Universe.

Now, if signal reaches from A to the spatial location of B before ot at the time B takes place, then viewing the situation from reference frame Y:

[list][*]Signal reached from A to (the spatial location of) B before B took place[*]B happened BEFORE A[/list]
Thus signal travelled backwards in time.
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[quote name='Discount_Flunky' timestamp='1317076118' post='4866247']
For instance many scientists are starting to find proof that humans have a sixth sense.
[/quote]

Humans are painfully predictable and creatures of habit. Google and Facebook are mining all this data to run their own "sixth sense". Gather enough data and you can tell, with 95% confidence what the person will do. "Enough" in this case means web activity. Visa has been able to predict many decisions people make solely from purchasing history for many years now.

Human brain works through pattern matching, much of it is subconscious. While called sixth sense, it's nothing more than learned experience.

In the end, there is nothing mystical about it. Like weather. Gather enough inputs, fit them through some statistical model and you end up with a good enough prediction for next few days. Biggest change in recent years is the availability of computing power and number of sensors. Both have advanced sufficiently to the point where individuals' actions can be predicted in same way as weather.

And over long term, it does mean pre-crime becomes viable. Not through paranormal activity, but through simple math operating on vast amounts of data. Retail will also change. So will jobs. Linkedin has been promising this for a while, but we aren't there yet. Generations born today however will be providing sufficient records through entire life through which the models will be built, and eventually used for their successors. All big companies are using such models already and have been for a while. Not with breakthrough success, but sofficient to notice various trends.
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[quote name='Lauris Kaplinski' timestamp='1317130943' post='4866433']
According to the theory of relativity there is NO preferred reference frame[/quote]
You mean that theory you intend to throw out of the window by positing a faster-than-fastest object?


[quote]...And all these descriptions are equally true descriptions of the Universe.[/quote]Assuming the axioms of relativity hold, yes. Little surprise one can derive a contradiction from inconsistenly applying ones axioms.
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[quote name='Eelco' timestamp='1317136235' post='4866465']
[quote name='Lauris Kaplinski' timestamp='1317130943' post='4866433']
According to the theory of relativity there is NO preferred reference frame[/quote]
You mean that theory you intend to throw out of the window by positing a faster-than-fastest object?
[quote]...And all these descriptions are equally true descriptions of the Universe.[/quote]Assuming the axioms of relativity hold, yes. Little surprise one can derive a contradiction from inconsistenly applying ones axioms.
[/quote]
Neutrinos moving faster than light in vacuum does not automatically refute the theory of relativity.

[list][*]It may be, that relativity still holds, but light itself moves slower than C[*]It may be, that neutrinos travel faster than C, but this process does not carry information[*]Even if neutrinos can carry information faster than C it may mean, that relativity still holds but causality, as we know it, does not exist in physical world[/list]
In any case, relativity, faster-than-light communication and causality do not seem to fit together. I personally hope that the last one will be thrown out and the universe turns out to be perfectly deterministic again :D
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[quote name='Antheus' timestamp='1317132944' post='4866447']
[quote name='Discount_Flunky' timestamp='1317076118' post='4866247']
For instance many scientists are starting to find proof that humans have a sixth sense.
[/quote]

Humans are painfully predictable and creatures of habit. Google and Facebook are mining all this data to run their own "sixth sense". Gather enough data and you can tell, with 95% confidence what the person will do. "Enough" in this case means web activity. Visa has been able to predict many decisions people make solely from purchasing history for many years now.

Human brain works through pattern matching, much of it is subconscious. While called sixth sense, it's nothing more than learned experience.

In the end, there is nothing mystical about it. Like weather. Gather enough inputs, fit them through some statistical model and you end up with a good enough prediction for next few days. Biggest change in recent years is the availability of computing power and number of sensors. Both have advanced sufficiently to the point where individuals' actions can be predicted in same way as weather.

And over long term, it does mean pre-crime becomes viable. Not through paranormal activity, but through simple math operating on vast amounts of data. Retail will also change. So will jobs. Linkedin has been promising this for a while, but we aren't there yet. Generations born today however will be providing sufficient records through entire life through which the models will be built, and eventually used for their successors. All big companies are using such models already and have been for a while. Not with breakthrough success, but sofficient to notice various trends.
[/quote]


If you don't know about the material you are talking about you can't dismiss it. What you are talking about is profiling which has nothing to do with a sixth sense if it exists.
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It's been a while since I studied relativity, so I've forgotten where the standard value of [font="'Courier New"]c[/font] comes from -- have we measured it through observation, or predicted its value from math, or both?

Could it simply be that we've simply been using a slightly incorrect value of [font="Courier New"]c[/font] all this time, and that this new experiment has delivered a more accurate measurement of [font="Courier New"]c[/font] ([i]which is slightly faster than our existing measurements[/i])?
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[quote name='Hodgman' timestamp='1317174802' post='4866661']
It's been a while since I studied relativity, so I've forgotten where the standard value of [font="Courier New"]c[/font] comes from -- have we measured it through observation, or predicted its value from math, or both?

Could it simply be that we've simply been using a slightly incorrect value of [font="Courier New"]c[/font] all this time, and that this new experiment has delivered a more accurate measurement of [font="Courier New"]c[/font] ([i]which is slightly faster than our existing measurements[/i])?
[/quote]

If this true that's what I think it is. Lights probably just faster then we thought it was. Won't change much of anything if it's true.
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[quote name='Hodgman' timestamp='1317174802' post='4866661']
It's been a while since I studied relativity, so I've forgotten where the standard value of [font="Courier New"]c[/font] comes from -- have we measured it through observation, or predicted its value from math, or both?

Could it simply be that we've simply been using a slightly incorrect value of [font="Courier New"]c[/font] all this time, and that this new experiment has delivered a more accurate measurement of [font="Courier New"]c[/font] ([i]which is slightly faster than our existing measurements[/i])?
[/quote]

[url="http://en.wikipedia.org/wiki/Speed_of_light"]It's[/url] been measured over and over and over and over again with consistently more refined results. If this would turn out to be the case, it would cast a shadow on generations of physicists in the past.

[quote]
[font="sans-serif"][size="2"]After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299,792,458 m/s with a relative [url="http://en.wikipedia.org/wiki/Measurement_uncertainty"]measurement uncertainty[/url] of 4 parts per billion (4e-9). [/size][/font][font=sans-serif][size=2] In 1983, the [url="http://en.wikipedia.org/wiki/Metre"]metre[/url] was redefined in the [url="http://en.wikipedia.org/wiki/International_System_of_Units"]International System of Units[/url] (SI) as the distance travelled by light in vacuum in[sup]1[/sup]?[sub]299,792,458[/sub] of a [url="http://en.wikipedia.org/wiki/Second"]second[/url]. As a result, the numerical value of [i]c[/i] in metres per second is now fixed exactly by the definition of the metre.[/size][/font]
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[quote name='irreversible' timestamp='1317185544' post='4866683']
[quote name='Hodgman' timestamp='1317174802' post='4866661']
It's been a while since I studied relativity, so I've forgotten where the standard value of [font="Courier New"]c[/font] comes from -- have we measured it through observation, or predicted its value from math, or both?

Could it simply be that we've simply been using a slightly incorrect value of [font="Courier New"]c[/font] all this time, and that this new experiment has delivered a more accurate measurement of [font="Courier New"]c[/font] ([i]which is slightly faster than our existing measurements[/i])?
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[url="http://en.wikipedia.org/wiki/Speed_of_light"]It's[/url] been measured over and over and over and over again with consistently more refined results. If this would turn out to be the case, it would cast a shadow on generations of physicists in the past.

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[font="sans-serif"][size="2"]After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299,792,458 m/s with a relative [url="http://en.wikipedia.org/wiki/Measurement_uncertainty"]measurement uncertainty[/url] of 4 parts per billion (4e-9). [/size][/font][font="sans-serif"][size="2"] In 1983, the [url="http://en.wikipedia.org/wiki/Metre"]metre[/url] was redefined in the [url="http://en.wikipedia.org/wiki/International_System_of_Units"]International System of Units[/url] (SI) as the distance travelled by light in vacuum in[sup]1[/sup]?[sub]299,792,458[/sub] of a [url="http://en.wikipedia.org/wiki/Second"]second[/url]. As a result, the numerical value of [i]c[/i] in metres per second is now fixed exactly by the definition of the metre.[/size][/font]
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If it's changed before it can be changed again. It wouldn't necessarily make scientists of before look bad.
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[quote name='irreversible' timestamp='1317034827' post='4866006']For instance, sending information back (and possibly forth) in time might all of a sudden become a practical problem rather than a theoretical one.[/quote]

Sorry to take the magic out of it, but that's not the case.

Neutrinos do not travel back in time, no matter how fast it turns out they were moving.

The principles of time-travel in relativity are due to a lack of a single fixed reference frame- which are the same principles that set c as the universal speed limit. It is in the nature of space-time as a single substance.


IF this turns out to be true, it means one (or more) of several things:

Something is effectively reducing the speed at which photons propagate (and perceived passage of time, since the electro-weak force is involved in material processes) that isn't affecting the neutrinos, or is not affecting them as strongly.

Cosmically, neutrinos do travel slower than light (such as from distant super novae); this may be a matter of context.

The neutrinos are not traveling faster than light if you don't factor in the space-time dilation caused by Earth's local gravity field.

That is to say, gravity may be slowing down time for light, but not for neutrinos, thus giving them an apparent relative boost.

The important consequences of that would seem to be that, yes, Einstein would have to be [i]partially[/i] wrong.

Special relativity would have to be thrown out, along with the inherent coupling of space and time, because in this case Neutrinos would provide evidence of a special independent frame of reference.

We would then have to offer alternative explanations for gravity, the perceived relativity of light speed, and time dilation.
It's relatively easy to compose working theories that fit the observations based on quantum mechanics, and I could go on to do that, but I'm already a little off topic.


The point is, that with a special frame of reference, space and time are independent of each other, special relativity is wrong, and velocities faster than c do not result in time travel.

Likely all this would do in the near future is give us a more accurate picture of gravity, solve UFT, explain dark matter and other Astronomical quirks, give us an irrefutable model of the start of the universe... which is nothing to sneeze at, but pretty much just academic. I wish I could say it would result in world peace by unifying the belief systems of all people in science... but that's not going to happen any time soon.

I would say, relevant to everyday life, it would probably give us a small leg up in quantum and optical computation resulting in profound annoyance to cryptographers. I'm not sure if this is a good thing or not, yet. Are we ready for post-quantum cryptography?

What I have to wonder, though, is what does quantum computation offer gaming? Maybe better sorting methods? I'm not much of a programmer, so I'm not sure.
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[quote name='Lauris Kaplinski' timestamp='1317143304' post='4866495']
Neutrinos moving faster than light in vacuum does not automatically refute the theory of relativity.

[list][*]It may be, that relativity still holds, but light itself moves slower than C[*]It may be, that neutrinos travel faster than C, but this process does not carry information[*]Even if neutrinos can carry information faster than C it may mean, that relativity still holds but causality, as we know it, does not exist in physical world[/list]
In any case, relativity, faster-than-light communication and causality do not seem to fit together. I personally hope that the last one will be thrown out and the universe turns out to be perfectly deterministic again :D
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3. Don't worry, the last one is definitely not the case. Violations of causality are prone to logical contradictions. Logic is the only thing we can always assume in any coherent discussion- with out which, the principle of explosion makes the conversation itself meaningless. In so far as we're thinking or talking about anything, logic holds- and so must causality.

2. Neutrinos carry information; that's how they were detected. Neutrino vs. no neutrino is information.

1. This is... [i]extremely[/i] unlikely. Like I mentioned in my post above, light may be being slowed down by something, but the only thing that would have been slowing down light in this experiment relative to cosmic observations would be gravity, and if we allow for gravity to slow down one thing, and not another, we have to disassociate space and time, which refutes special relativity by creating a special reference frame (space) independent of the passage of time experienced by different matter/energy in different places.
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[quote name='driftingSpaceMan' timestamp='1317254014' post='4867000']
[quote name='Lauris Kaplinski' timestamp='1317143304' post='4866495']
Neutrinos moving faster than light in vacuum does not automatically refute the theory of relativity.

[list][*]It may be, that relativity still holds, but light itself moves slower than C[*]It may be, that neutrinos travel faster than C, but this process does not carry information[*]Even if neutrinos can carry information faster than C it may mean, that relativity still holds but causality, as we know it, does not exist in physical world[/list]
In any case, relativity, faster-than-light communication and causality do not seem to fit together. I personally hope that the last one will be thrown out and the universe turns out to be perfectly deterministic again :D
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3. Don't worry, the last one is definitely not the case. Violations of causality are prone to logical contradictions. Logic is the only thing we can always assume in any coherent discussion- with out which, the principle of explosion makes the conversation itself meaningless. In so far as we're thinking or talking about anything, logic holds- and so must causality.
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Causality in philosophy already is logically incoherent, so not big loss here.

Also strictly deterministic theories, like pure Newtonian physics are time-symmetric and thus have no place for true causality. If ball A hits ball B and "causes" it to move, you can simply invert time and say, that ball B "caused" the movement of ball A backwards in time. We can only distinguish between them because of intuitive assignment of causality with forward-in-time influences, but this has no any physical meaning.

If Qm anf GTR taught us anything, the most important thing is, that we cannot carry the notions of our day-to-day logic naively into physical realms. Of course the theories have to be logically coherent - but "normal" causality does not belong to that part of logic.

[quote name='driftingSpaceMan' timestamp='1317254014' post='4867000']
2. Neutrinos carry information; that's how they were detected. Neutrino vs. no neutrino is information.

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Probably. I simply do not know enough to exclude any entanglement-like setups, where we can post-factum establish, that neutrinos in CERN and Italy "appeared" within certain time interval but not have enough control in CERN to "set" the starting point of given time interval with enough precision.

[quote name='driftingSpaceMan' timestamp='1317254014' post='4867000'] 1. This is... [i]extremely[/i] unlikely. Like I mentioned in my post above, light may be being slowed down by something, but the only thing that would have been slowing down light in this experiment relative to cosmic observations would be gravity, and if we allow for gravity to slow down one thing, and not another, we have to disassociate space and time, which refutes special relativity by creating a special reference frame (space) independent of the passage of time experienced by different matter/energy in different places.
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Why is gravity "the only thing" that could have slowed down light?

How about our theory of light is completely wrong and it never moves with speed C but always slightly slower depending on other factors than gravity? Thus both special and general relativity can still hold (as C being constant in all reference frames but not the speed of light).


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[quote]

Why is gravity "the only thing" that could have slowed down light?

How about our theory of light is completely wrong and it never moves with speed C but always slightly slower depending on other factors than gravity? Thus both special and general relativity can still hold (as C being constant in all reference frames but not the speed of light).



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Also gravity itself does not effect light. It can effect space time which in turn effects light, but without mass gravity can't act on it. (Just pointing it out not really a comment towards you)
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