Faster than light?

[SpliFF]

From Fukushima thread...

Actually stuff published in peer reviewed journals, even in high impact, is often extremely crazy, more shocking than the craziest conspiracy theories people invent

Actually the wackiest theory in my opinion is that nothing can travel faster than light. As far as I can tell the concept is based on mathematics and that fact nobody has ever measured anything traveling faster than light.

I'm still waiting to hear of an instrument capable of detecting faster than light objects. Surely there's a point where an objects speed would defy attempts to measure it using traditional sensors.
Such an instrument would be difficult to verify because it would also require either very high timing accuracy or sensors spread out across interplanetary distances - plus the ability to categorically prove that the particle detected at each sensor was the same one.

I get the feeling this is a case where science simply deferred to Einstein due to his fame and the difficulty of proving him wrong (rather than requiring him to prove himself right).

Also I heard this has been debunked already due to evidence of light being slowed by gravitational effects. If it can be slowed then presumably it can also be accelerated (and therefore "speed of light" is not really a stable constant).

I'm just curious if anyone knows more about this?

[Coresair]

I am not sure about light itself being accelerated but I don't think any object can exceed or even meet the speed of light. E=mc^2

I interpreted that as meaning energy can add mass (infact this is recorded in some instanced) So as an object gains kinetic energy it also gains mass, which becomes more pronounced the more kinetic energy being applies. You need infinite energy to propel an object to the speed of light.

[SwiftSpear]

You misunderstand the issue with traveling faster than light. It's not that light has some magical property to it that prevents other things from traveling faster than it, it's that there is a maximum speed any object can be traveling relative to any other object, and light is one of many things that travel at that speed. It doesn't do any damage to that theory to make light travel slower than it normally does. It just means you can make light travel slower than the maximum observable speed of any material object, it doesn't mean that maximum speed doesn't exist.

Say you have White on your PC. 0,0,0. The argument you've made is that, you can make white darker by increasing it's value, therefore you should be able to make it lighter as well. This is false because it's at the maximum whiteness in it's default state. Yes, it can be made darker, but it cannot be made to exceed the maximum.

I'm not familiar with the actual proofs behind the theory, but there have been many tests to show that the theory of relativity is accurate.

Here is what wikipedia says:
http://en.wikipedia.org/wiki/Tests_of_g ... relativity

[Hobo Joe]

Einstein has been proven wrong many times, and there is no stigma against going against him in particular, but there has been no evidence that objects CAN travel faster than light, and until there is, it won't be challenged. Maybe we'll make a breakthrough someday and create a device with FTL capabilities but until then, the idea that objects can't go faster than light, or that it would take all the energy in the universe to do so - remains firm.

It's a theory that has a lot of basis in evidence, and the reason it isn't challenged is not because of rigid ideologists, but the fact that there's no compelling evidence against it, although that's not to say there aren't a lot of hypothesis' floating around on the subject.

[SanadaUjiosan]

Don't worry, the problem will be negated: Scientists will increase the speed of light in 2208.

But seriously, I've pondered this kind of thing too. What I always took from it is that something would be invisible if it moved faster than the speed of light (I'm not sure if this is actually stated anywhere by anyone, it may be some conclusion I came to on my own while in school) and therefore would be difficult if not impossible to detect with contemporary instruments.

Perhaps there's a lot of stuff traveling faster than the speed of light all the time and we just have no idea of its existence.

[Gota]

WTF...first you need the math to somehow circumvent einstein's theories about FTL travel.
Than and only than can you start thinking of how to measure such movement of particles if it actually exists....
A dilettante trying to say FTL is probably possible and Einstein didnt know WTF he was talking about just sounds moronic.

[Hobo Joe]

Don't worry, the problem will be negated: Scientists will increase the speed of light in 2208.

But seriously, I've pondered this kind of thing too. What I always took from it is that something would be invisible if it moved faster than the speed of light (I'm not sure if this is actually stated anywhere by anyone, it may be some conclusion I came to on my own while in school) and therefore would be difficult if not impossible to detect with contemporary instruments.

Perhaps there's a lot of stuff traveling faster than the speed of light all the time and we just have no idea of its existence.

It would only be 'invisible' if it was traveling towards you. Once it passed you, the light being emitted would be visible.

[luckywaldo7]

I am not sure about light itself being accelerated but I don't think any object can exceed or even meet the speed of light. E=mc^2

I interpreted that as meaning energy can add mass (infact this is recorded in some instanced) So as an object gains kinetic energy it also gains mass, which becomes more pronounced the more kinetic energy being applies. You need infinite energy to propel an object to the speed of light.

This is about my understanding of it. So theoretically nothing can go faster then a massless particle, like a photon.

[TradeMark]

A side question... How fast gravity "moves" ? If there suddenly appeared a second sun in our system, when would we get affected by its gravity? as fast as light comes from it? i bet its faster than light. might even be instantaneous effect, no delay.

[Johannes]

http://en.wikipedia.org/wiki/Speed_of_gravity

[AF]

Speed is not purely speed, this belies a fundamental misunderstanding of how relativity works. As you approach the speed of light, the energy required to get faster increases exponentially. To reach the speed of light you would need an infinite amount of energy to propel a finite amount of mass.

It is also ignorant of the relativistic effects upon weight and passage of time.

But eitherway, einstein HAS been challenged, and theories abound, but nothing has been proven despite attempts. The most notable being the tachyon particle theory, for which no conclusive evidence has ever been found http://en.wikipedia.org/wiki/Tachyon

Light itself is a force carrier, and has no mass (not in the conventional sense), as such it is capable of travelling at said maximum speed ( although it can be slowed ). According to numerous theories, light itself is inherently timeless, and could be moving backwards in time or forwards, or both, but we could have a very long heated discussion over that and other finer points of Quantum Chronodynamics and other theories of which I lack the finer details to discuss effectively.

Even then, FTL communication or travel is inherently problematic:

http://en.wikipedia.org/wiki/Tachyonic_antitelephone

[AF]

A side question... How fast gravity "moves" ? If there suddenly appeared a second sun in our system, when would we get affected by its gravity? as fast as light comes from it? i bet its faster than light. might even be instantaneous effect, no delay.

Drop a second marble onto a rubber plane, does the marble arrive at its fully depressed position instantaneously? Or does the rubber move to its new position?

[dansan]

There are various theories describing the phenomenon of "gravity". The one which is experimentally most "proven" is the general relativity theory. It's answer to your question is, that a gravity well would move at light speed.
Newtons laws make gravity instantaneous in the hole universe. Mostly to make calculations easier. But it results in observable errors of some planetary courses.

[dansan]

Years ago I saw a documentary where they made _information_ move faster than light with the result that the music (the transmitted information) arrived at the receptor _before_ being sent. I'll try to find the documentary and post it if I do.
Please don't argue with me about it until then - I really cannot remember much of it, and will not defend it in any way :)

[Gota]

http://en.wikipedia.org/wiki/Alcubierre_drive

[TradeMark]

http://en.wikipedia.org/wiki/Speed_of_gravity

Hmm.. reading a bit of that i came up with another question...

If there appeared a second sun in our system, wouldnt the sudden gravity wave actually make a physical impact that can be felt on earth? because the difference of our current motion would change dramatically all of sudden.

So when you first see the light coming from second sun, you would also feel huge tremor under your feets because the earth would suddenly start moving to different direction... might even tear the ground apart and cause volcano eruptions all over the world.

[momfreeek]

force (gravity) manifests as acceleration. So it would be an immediate change in acceleration (and a gradual change in velocity) and it would affect every particle on or around earth rather than there being any anchor so I don't see any stress or strain involved. Propagation of the effects all move at one speed (all forces.. and its gravity that holds the earth together anyway).

Then again the tides are caused by changes in gravity as the moon moves around the earth so maybe I'm wrong. Is the tidal effect dependant on the proximity of the moon having a greater effect on closer particles?

edit: the answer is yes. So its this that could cause a shockwave (as the closer side of the earth is affected more).. but at the distance of the sun I think this effect would be imperceptible (not sure)

But seriously, I've pondered this kind of thing too. What I always took from it is that something would be invisible if it moved faster than the speed of light (I'm not sure if this is actually stated anywhere by anyone, it may be some conclusion I came to on my own while in school) and therefore would be difficult if not impossible to detect with contemporary instruments.

Perhaps there's a lot of stuff traveling faster than the speed of light all the time and we just have no idea of its existence.

I pondered this too. All we can see is light, and the particles we are made from and related things. Energy and a few different forces. There could be whole other sets of "energy" and forces alongside us that we simply do not interact with (or we do in ways we cannot fathom). Is this the alternate universe theory?

[dansan]

Years ago I saw a documentary where they made _information_ move faster than light

Found it. It was about an experiment at the university of K├Âln (germany): http://en.wikipedia.org/wiki/Faster-tha ... nelling.29
The interpretation of the experiment seems to be controversial.

In general I understood that it is not impossible to have something move faster than light. The thing about matter is, that it cannot _cross_ from below light speed (LS) to above LS.
You can have a single bit "travel" faster than LS by measuring the same quantum spin at the same time at two places in the universe. But as you cannot use that to transmit information you are not actually making anything _move_.
All this made me read like ten Wikipedia pages about astronomy and quantum stuff - fascinating shit...

[RogerN]

There's another simple answer to why nothing can move faster than light: at superluminal speeds it would be possible to violate causality, create paradoxes, send messages back in time to yourself, and generally screw up reality.

See this page for an explanation of how that works: Relativity and Causality

[Licho]

Actually there is plenty of papers describing quantum tunneling effectively giving photon or even particle with mass superluminar speed.

Even claims of transmitting information this way (which would of course push hard against that paradox).

Quantum teleportation (actual tested things) needs information to even travel to past (quantum information only, not classical).

And of course entanglement action happens at higher than light speed too..

So while as far as we know there is no simple way to move macroscopic object at higher than light speed due to effects of relativity, there are plenty ways around..

The only known way to move macroscopic objects at higher than light speed is wormholes and changing topology of spacetime.