Not to mention that if neutrinos can travel faster than light, then so can macroscopic objects. If information can be sent faster than light, it opens the door to instantaneous teleportation across the universe. You could scan the position of every atom in your body, then step into a machine that would kill you, instantly transmit the information about your atomic composition to a receiver device on a distant world, and be reassembled by the receiver on that world.
I have no idea what THAT would do to causality (or if relativity would even apply in such a bizarre situation) but it would certainly result in a lot of weirdness.
I find it hard to believe that neutrinos, given their small extremely small mass, behave like little tennis balls even at near-light velocities. They should behave more like wave packets (i. e. photons or low energy electrons).
My intuitive hunch is that the lighter something is, the more easy it is to make it cross the warp barrier. And since neutrinos have almost no mass, . . .
Possibly. But there is nothing in the known laws of physics to indicate that that would be the case. What especially interests me about this experiment is that even though the neutrinos supposedly exceeded the speed of light, they just barely exceeded it (a very small fraction of a percent). But once we've crossed that barrier there is theoretically no reason they couldn't travel much faster...at an arbitrarily fast speed.
I don't see how (which isn't necessarily to say that it's impossible). Special relativity indicates that the laws of physics should look the same to everyone, regardless of their frame of reference. If neutrinos can travel faster than light, that means that it should be possible to send information faster than light. For example, if you stand on Earth and I stand on Betelgeuse and we fire beams of superluminal neutrinos at each other in Morse Code, we could communicate instantly even though we were 640 light-years apart.
And being able to send information faster-than-light DOES have serious repercussions for causality. For example, suppose I've rigged up a series of Christmas lights in a straight line across our section of the galaxy. I've set them up so that I'll send a superluminal neutrino signal to Light 1, which will then turn itself on and send a superluminal signal to Light 2 to do the same, etc. If you're in a spaceship traveling at near the speed of light in the same direction as my superluminal neutrino signal, from your perspective you would see Light 2 turn itself on before Light 1 ever sent it a signal to do so! Since there is nothing special about my frame of reference, I can't say that my interpretation of causality is correct and yours is wrong. You would have witnessed an effect happening before its cause, and your perception of the events would be just as valid as mine.
Okay. Very good points. But we don't know what properties of the neutrinos allow it to go FTL. So while it brings up a whole lot of options, it also means we don't know what options are closed to us.
I can see that it would be potentially possible for instantaneous communication. But aren't there practical limits? For example, if I can send a signal twice the speed of light wouldn't that mean that my Morse Code signal from Earth only get to Betelgeuse in 320 years instead of 640?
I mean as you say these neutrinos seemed to only go a very small percentage faster than light. But shouldn't there be a difference between someone being able to go a small percentage faster than c and someone being able to go a large percentage faster than c?
Okay. So wouldn't that mean that being able to go FTL would only put us at a higher dimension of time?
I once had a friend try to explain how dimensions would seem to entities from a different dimension. My friend explained to me how a 2-dimensional being would perceive a 3-dimensional cone. If it would travel from the point of the cone to the base, it would only see a point that got larger and larger and larger until it became a circle the circumference of the base of the cone.
So maybe with FTL we would be able to go to the next dimension of time. Effectively, people in 1-dimensional time would face the repercussions of manipulated causality but people in 2-dimensional time would witness that event linearly.
Isn't it generally accepted that those types of particles behave like both?
Their mass shouldn't really matter (other than the fact that they have mass at all), because relativity indicates that as massive objects approach the speed of light, their mass approaches infinity. Since force equals mass times acceleration, it should be impossible to accelerate any particle beyond the speed of light because it would require an infinite amount of force.
The only known universal speed limit, is the speed of light. So once you have a way to break that speed limit, there isn't any additional upper bound to speed (that we know of), which means that you can send information instantaneously for all intents and purposes. If there is some speed limit that hasn't yet been discovered, which is greater than the speed of light but less than infinity, there might be practical limitations. But the same basic logic would apply, you'd just have to assume longer-lived scientists for the purposes of that thought experiment.
If there is any difference, the currently-known laws of physics do not account for it.
That is essentially accurate for how a 2-dimensional being would view the third dimension. But all prominent theories and hypotheses indicate that there is only 1 dimension of time. String theory says that our universe consists of 10 or 11 dimensions...but they are all spatial dimensions except for the 1 time dimension that we already know of. But to answer your question, yes, if neutrinos can travel faster than light it would throw open the door to time travel.
And being able to send information faster-than-light DOES have serious repercussions for causality. For example, suppose I've rigged up a series of Christmas lights in a straight line across our section of the galaxy. I've set them up so that I'll send a superluminal neutrino signal to Light 1, which will then turn itself on and send a superluminal signal to Light 2 to do the same, etc. If you're in a spaceship traveling at near the speed of light in the same direction as my superluminal neutrino signal, from your perspective you would see Light 2 turn itself on before Light 1 ever sent it a signal to do so! Since there is nothing special about my frame of reference, I can't say that my interpretation of causality is correct and yours is wrong. You would have witnessed an effect happening before its cause, and your perception of the events would be just as valid as mine.
Yes, but we're talking about neutrinos. Even if the neutrino is traveling at .9999999999999c, it's still won't amount to a billionth of a feather in (relativistic) mass.
Time and space...if relativity be real than physics must work (assuming uniform motion) in any frame of reference. No frame of reference can be superior to any other. This is difficult. It always has been.This isn't a criticism, but a mere question to help me understand the concept. Is speed not relative? It seems to me that light itself would exceed C if the frame of reference were also moving in the opposite direction of that light, or at least would be measured to be higher. I always thought of C as a speed with the reference point being space itself (the grid points of the universe if you will), though maybe I'm missing some ideas from relativity. If the Earth were to move in the opposite direction of light through space, couldn't an observer then measure the speed of light to be higher than C relative to the earth?
No. Time dilates. And space shortens in the direction of travel. Each observer believes itself to be standing still and sees the other as moving at whatever the appropriate speed is.well, here's my question: is everything is relative, doesn't that mean that if one object is moving at 3/4 the speed of light in one direction, and another object is moving at 3/4 the speed of light in another...when they pass each other...won't it appear that they are both moving at 150% the speed of light?
So what you're saying is that physicists see no difference between "greater than c" and "infinity"?
Okay, before we go on, let me clear something up with regards to the example you gave here:
1) There's a series of lights strung throughout the galaxy
2) For the next light to turn itself on the light before must turn on first and must do so within a certain interval.
3) If we use a subluminal signal to activate the lights, people at subluminal speeds traveling beside the lights will see Light 2 turn on at the interval after Light 1 turns on.
4) If we use an FTL signal to activate the lights, people at subluminal speeds traveling beside the lights will see Light 2 turn on before the interval after Light 1. However, those people will still see Light 1 turn on before Light 2.
5) If we use an FTL singal to activate the lights, people at the same FTL speed traveling beside the lights will see Light 2 turn on at the interval after Light 1 turns on.
Are these points right?
If they are not right, which points aren't?
For these points that aren't, why aren't they?
Everything has both particle and wave properties.Isn't it generally accepted that those types of particles behave like both?
But we aren't talking about neutrinos traveling at .9999999999999c. These neutrinos (allegedly) exceeded the speed of light, which is substantially different. If you put enough 9s on that decimal, eventually that neutrino will be as massive as the entire universe. It cannot exceed the speed of light because an infinite mass would require an infinite force to accelerate it further.
4) No. Light 1 turning on and Light 1 sending out its signal are simultaneous events, in this thought experiment. If the observer is traveling in the direction of the signal (i.e. from Light 1 to Light 2) near light speed, they will see Light 2 turn on before they see Light 1 turn on or send out its signal. It will appear to them as though Light 2 has turned on for no reason at all, which is a no-no according to our current understanding of causality.
5) I'm actually not sure what would happen if the observer was traveling faster than light. Theoretically, they would be moving backwards in time if they are traveling faster than light...so what I *think* would happen is that they would observe things the same way as in (4), but unlike in (4) this would appear normal to them that effects should precede causes, since they are time traveling into the past.
Warp speed!!
Well that just means that we have to classify neutrinos as something else that doesn't follow Einsteins laws of relativity...
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