Superluminal Speeds Possible?

[Marie Louise von Preussen]

Consider an object a moving through space. Is it, theoretically, ever possible to make it move faster than the light? If phisically possible, how much energy would that object would ever require, again theoretically speaking.

I'm quite a layman in phisics, so keep it readable without much of the phisical jargon if possible, but I don't mind to decipher equations.

[Ummagumma]

As far as we (or they, rather..) can tell, it would require infinite energy as you would achieve infinite mass.
As all our observations are based from on or near a planet, near a star in a galaxy we are in a bit of a gravity sink-hole though. Where space-time is less compressed, who knows what may happen (Are our measurements to other stars even accurate?)

[the_mango55]

From what I understand, nothing travels faster than light, but the speed of light varies.

For example, the universe is apparently has a radius of over 40 billion light years. Since the universe is only about 14 billion years old, there is obviously a way for matter to travel faster than our conventional measurement of lightspeed (light travels one lightyear per year), even if it isn't actually faster than light (because light travels faster in those circumstances).

So, I guess the answer is that it is impossible to go faster than light would travel in an identical situation, but it is apparently possible to go faster in some situation than light travels on earth.

someone correct me if I'm wrong.

[Juvenal]

...the universe is apparently has a radius of over 40 billion light years...

This sparked my interest. The current estimated age of the Universe is around 14 Billion years, so you might assume the observable universe has a radius of 14 Billion light years.

Here is an article on SPACE.COM from 2004 saying that the estimated radius of the observable universe is 78 Billion light years.

http://www.space.com/scienceastronom...ay_040524.html

The argument is that light arriving at Earth today from the beginning of the universe has beeen travelling 13.7 Billion years, but in that time space itself has expanded so that the light has travelled further than the the actual space traversed!

I don't think we have a size for the whole universe because light from anything further than 78 Billion light years hasn't reached us yet.

[Kiljan Arslan]

So your saying one could possibly make light travel faster than 186,000 miles a second right?

[the_mango55]

possibly, although I have no idea how anyone would make that happen. I'm no physicist either.

Perhaps it's not possible, perhaps it takes too much energy to be feasible, perhaps it's relatively simple and has just eluded our research so far.

Lets hope we get the answers to all these questions when they turn on the Hadron Collider in May (and that it doesn't kill us all ).

[Kiljan Arslan]

Yes let us hope.

[Cataclysm]

Simetrical is conspicuously absent from this discussion.

How can the universe be 40 billion lightyears across if its only 14 billion years old? This is puzzling.

[Syron]

How can the universe be 40 billion lightyears across if its only 14 billion years old? This is puzzling.

Erm because as stated in the article while matter has a speed limit, the expansion of space does not. The distance between two galaxies can increase faster than the speed of light.

[Cataclysm]

Erm because as stated in the article while matter has a speed limit, the expansion of space does not. The distance between two galaxies can increase faster than the speed of light.

How? Unless the galaxies themselves are moving apart faster than light, how can the distance grow faster than light?

[Ummagumma]

How? Unless the galaxies themselves are moving apart faster than light, how can the distance grow faster than light?

If you have 2 entities, both travelling from a central point at the speed of light, how fast are they travelling relative to each other? Add a few other objects only travelling at near light speed relative to it's neighbour and from end to end the speeds are incalculable.
Without any way to prove this, I 'assume' that, as speed is only ever relative to space, light has a different speed in different areas. We are in a big sink hole of space/time, after all. In the gaps between solar systems, and even between galaxies we have absolutely no way of knowing as yet. All our distances of the universe just might be very far off due to the compression of anything we observe. Of course I could be totally wrong.

[Cataclysm]

If you have 2 entities, both travelling from a central point at the speed of light, how fast are they travelling relative to each other? Add a few other objects only travelling at near light speed relative to it's neighbour and from end to end the speeds are incalculable.
Without any way to prove this, I 'assume' that, as speed is only ever relative to space, light has a different speed in different areas. We are in a big sink hole of space/time, after all. In the gaps between solar systems, and even between galaxies we have absolutely no way of knowing as yet. All our distances of the universe just might be very far off due to the compression of anything we observe. Of course I could be totally wrong.

Understood, but if two bodies are moving away from eachother at the speed of light, they would be two lightyears apart after one year. 14 billion*2= 28 billion lighyears across, nowhere near 40 billion.

[Kiljan Arslan]

Or else light can travel at varying speeds.

[Syron]

Or else light can travel at varying speeds.

Not enough evidence for that, and the concept that expansion of space has no limit is a prediction of General Relativity.

[Big War Bird]

Tachyons are hypothetical particles capable of superluminal speed. If somehow we could make a ship adopt the properties of a tachyon then faster than light travel would be possible. Of course this would require a major expansion in our understanding of physics and technology we can scarcely imagine.

[Nergal1610]

Is it, theoretically, ever possible to make it move faster than the light? If phisically possible, how much energy would that object would ever require, again theoretically speaking.

As far as I know, in order for an object to move faster than the light, it needs either of these two things: infinite source of energy or it must not have any mass. So if an object has mass and it is not moving at lightspeed, it can never accelerate to lightspeed because the energy required for such an acceleration is infinite.
For example, photon is able to travel at lightspeed because it doesn't have invariant mass.

I would think that, if something traveled faster than the light, the laws of time and place ceased being valid. Or thats what my teacher told me.

(this post was written by a student who has studied physics only for half a year. If you find any errors, feel free to bash me )

[GrnEyedDvl]

This is far from my field of expertise, but supposedly sending light and energy at faster than light speeds has already been done. I remember several years ago they said they broke the speed of light in a cesium chamber, and there have been severel experiments since then.

http://www.space.com/scienceastronom..._c_000719.html
http://www.telegraph.co.uk/earth/mai...cispeed116.xml
http://www.newscientist.com/article/...c-lab-kit.html

Now sending actual matter faster than light is a different story.

[Syron]

This is far from my field of expertise, but supposedly sending light and energy at faster than light speeds has already been done. I remember several years ago they said they broke the speed of light in a cesium chamber, and there have been severel experiments since then.

http://www.space.com/scienceastronom..._c_000719.html
http://www.telegraph.co.uk/earth/mai...cispeed116.xml
http://www.newscientist.com/article/...c-lab-kit.html

Now sending actual matter faster than light is a different story.

In those experiments it wasn't the Front Velocity that exceeded the speed of light, it was the Group velocity.

The Group velocity of light carries no information and hence it isn't bound by Special Relativity. Group velocity of a wave can travel faster than the speed of light and there are plenty of experiments that have shown this.

The Front Velocity, what we would normally call the Velocity, does carry information and hasn't been conclusively shown to go superluminal in any experiment.

See, this is why making statements in physics/science is difficult since you need to know all the effects going on.

[Nergal1610]

If you have 2 entities, both travelling from a central point at the speed of light, how fast are they travelling relative to each other? Add a few other objects only travelling at near light speed relative to it's neighbour and from end to end the speeds are incalculable.
Without any way to prove this, I 'assume' that, as speed is only ever relative to space, light has a different speed in different areas. We are in a big sink hole of space/time, after all. In the gaps between solar systems, and even between galaxies we have absolutely no way of knowing as yet. All our distances of the universe just might be very far off due to the compression of anything we observe. Of course I could be totally wrong.

IIRC the light doesn't act very much as normal particles. For example, if you are driving a car at 40 km/h and use a sling to throw a rock at the speed of 10 km/h, the overall speed of the rock will be 50 km/h.
However, light does not function in the same way. If you drove the same car again and flashed the headlights, the light would still leave from the car at the speed of about 300 000 km/s. If you were moving at 1/10 of lightspeed (as if that never happened lol) and flashed your flashlight, the light from the flashlight would still travel at about 300 000 km/s.

So if I had an object A and an object B. They both would use some mechanism to travel exactly at lightspeed. Then I place the objects in opposite directions and they start to accelerate to their speed of 300 000km/h. Now comes the tricky part. What happens is that the object B is moving at 300 000km/h away from the object A and object A is moving at 300 000 km/h away from the object B.

I hope I explained my thoughts as difficultly as possible.

[Juvenal]

Understood, but if two bodies are moving away from eachother at the speed of light, they would be two lightyears apart after one year. 14 billion*2= 28 billion lighyears across, nowhere near 40 billion.

Firstly, no body with mass can travel at the speed of light.

Light emitted from a body 14 billion years ago has travelled 14 billion light years. But during that time space itself has expanded so that the light is now more than 14 billion light years from its source, even though it hasn't actually travelled through all of that space.

The analogy is a object travelling at constant speed around a balloon while it is being filled with air. The expansion of the balloon increases the length of the path already traversed.