Can something move faster than light?

[CraigD]

Perhaps instead of asking if something can move faster than light?, the question should be: Will it ever be possible to circumvent the barrier imposed by C. Circumvent being the key word.

…

Is their possibly another way to get from A to B by going round the inside of the track to the finish line?

I agree, these is a much better question, and one that considerable effort by many good physicists has gone toward answering

 

In 1994, in his excellent pop science book “Black Holes and Time Warps: Einstein's Outrageous Legacy”, Kip Thorne dedicated many pages to it. To summarize the human narrative of Thorne’s involvement: In the early 1980s, astronomer Carl Sagan, was working on his first and only work of fiction, the soon to very popular novel ”Contact”. Central to the plot was a character traveling vast distances in far less time than light requires. Wishing to have the most scientifically reasonable justification for this, Sagan asked experts friends such as Thorne for help.

 

With the assistance of his several graduate students, Thorne set out to provide such an explanation. The result was detailed speculation and supporting physics concerning the construction of artificial wormholes connecting distant points in such a way that the distance between the points was much shorter for a path inside the wormhole than for one outside it.

 

The basic “how to” manual of a Sagan-Thorne artificial wormhole are:

1. Using “exotic matter” (more about this below), you build a device consisting of 2 closely spaced, movable “mouths”;
   
2. Using conventional, sub-lightspeed means (something as simple as a spacecraft not much faster than Voyager 1, you move one mouth to wherever in the universe you want it (B);
   
3. To get quickly between the two places (A and B) where the wormhole mouths are located (which may be in motion relative to one another), you just fly through the wormhole.
   

Although this “advance interstellar subway” concept, with a few dramatic embellishments, satisfied Sagan’s novelistic needs, it had some obvious and discomforting implications. A major one is that the same technique that allows the connection of 2 distant points can be used to make a “time machine” connecting 2 points nearby in space but distant in time, using this slight variation on the previous “how to” manual:

1. Using “exotic matter”, you build a device consisting of 2 closely spaced, movable “mouths”;
   
2. Using a spacecraft, you accelerate one mouth to the greatest speed (V) of which you are capable;
   
3. You fly the spacecraft for enough time (T, as measured from the starting point) that, per Special Relativity, the difference between clocks at the mouths is [math]\Delta t = T \left (\frac{1}{\sqrt{1 - \frac{V^2}{c^2}}} – 1 \right ) [/math];
   
4. Returning to you starting place, you place the wormholes mouths near one another;
   
5. To travel backward in time [math]\delta t[math] seconds, you fly though the mouth you didn’t move, emerging from the mouth you did (A to B). To travel forward in time the same amount, you fly through the mouths the other direction (B to A).
   

The possibility of such a machine brings with it all the troubling paradoxes of time travel, such as: At date/time X, you go back in time and have a conversation with yourself convincing yourself not to be anywhere near the time machine at date/time X, a “causality violation”.

 

Paradoxes like these are so troubling that theorists such as Steven Hawking have proposed that what Thorne proposes can’t be done, due to what is jokingly referred to as “cosmic censorship”. The essence of Hawking’s argument against wormholes – the time machine kind in particular - is that, try as you will, you won’t be able to prevent “unattached” photons from getting into mouth A, traveling back in time to emerge from mouth B, then traveling through normal space to reenter A, and so on, until such a huge number of copies of the same photon are in the machine that whatever you’ve made the machine of is disintegrated by the intense light. Hawking and Thorne have made one of their famous wagers concerning whether a wormhole can work or not, though I suspect neither of them expects to live long enough to see the wager settled.

 

A critical reader will have noticed a bit of hand waving and “magic pixie dust” sprinkling above, in the use of “exotic matter”, so some explanation is in order.

 

From General relativity, we know that building a region of space such that the distance between 2 point is much longer for a path passing though the region than for one passing around it is, in principle, easy: just accumulate a lot of matter in the region – a nearby black hole will do nicely. An unpropelled spacecraft coasting through that region on its way from A to B can, without appearing to its passengers to have moved at a lesser average velocity, take much longer than one going from A to B on a path outside it. What Thorne and other wormhole theorists have proposed is, to state it in a very (and slightly overly) simplified way, a region with an opposite effect could be made by accumulating a lot of an “opposite” kind of matter. For lack of a more imaginative name, they call this “exotic matter”, and commonly refer to it as having “negative mass” or “negative gravitational pressure”.

Craig, would you be so kind as to stop tantalizing us and elaborate on the tantalizing experiments.

The “tantalizing” question is “is there really such a thing as exotic matter?”

 

The answer (a big “maybe”), as best I can explain, doesn’t I’m afraid do much to diminish the tantalizing. The main experiment I (and Thorne, and others who do such experiments or know people who do) am referring to are ones measuring the Casimir effect. This post is already too long for me to begin inexpertly attempting to explain the Casimir effect, so I’ll just direct you to the sentence in the wikipedia link that reads “Further research has shown that, with materials of certain permittivity and permeability, or with a certain configuration, the Casimir effect could be made repulsive instead of attractive, although there are no experimental demonstrations of these predictions.” This is the tantalizing part. Theorists suspect, for reasons beyond my understanding, that such matter might be the “exotic” type needed to build Sagan-Thorne-type wormholes/time machines.

[Farsight]

Craig: spookily enough I've just mentioned Kip Thorne on the TIME EXPLAINED thread I started. I'd really welcome your feedback on it, even if it leaves me holed and sinking.

[Agen]

Well correct me if I'm wrong, but can't one object move faster that the speed of lite in reference to another object as long as the two objects are in different systems?

[InfiniteNow]

Well correct me if I'm wrong, but can't one object move faster that the speed of lite in reference to another object as long as the two objects are in different systems?

 

Not according to our current understanding of the universe. There is a hard stop at the speed of light ©, and there isn't enough energy in the universe to accelerate objects faster... according to our current understanding. :xx:

[Agen]

But in theory?

 

What I mean is if a galaxy is moving a 0.999999 c and there is an "object" nearby to it that is in a stopped position. The galaxy bypasses it at 0.999999 c, but some of the stars that are orbiting whatever is in the center of the galaxy would pass the object that is "standing still" faster than c ?

[InfiniteNow]

But in theory?

 

What I mean is of a galaxy is moving a 0.999999 c and there is an "object" nearby to it that is in a stopped position. The galaxy bypasses it at 0.999999 c, but some of the stars that are orbiting whatever is in the center of the galaxy would pass the object that is "standing still" faster than c ?

 

Nope.

 

The speed of light is constant (from Einstein Light)

 

Michelson, Morley and the speed of light. From Einstein Light

 

 

 

Special Relativity

Galileo's Perspective: The animated picture below shows a train moving past an observer who is stationary relative to us. There is a person on the train throwing a ball at constant speed. The person standing sees the ball move at a constant speed equal to the train's speed plus the speed that the person on the train actually throws it.

This is the way that people have been figuring out combined speeds since the days of Galileo and Newton. In this type of world the two frames of reference are within the same temporal universe. Only one universe time is necessary. Light is expected to act exactly like the ball acts.

 

 

 

 

Einstein's Perspective: The animated picture below shows a train moving past an observer who is stationary relative to us. There is a person on the train shining a light beam, which necessarily goes at constant speed. The person standing does not see the light beam move at a constant speed equal to the train's speed plus the speed that the person on the train actually sees it leave his flashlight.

Light is special. This forces the train observer to live in a different temporal universe from the ground observer. His time values will be different for all events.

[Agen]

Hmm... well what if the train in the first picture where to be moving at c. What would stop the ball from moving faster than c in reference to the observer?

[Agen]

Perhaps time dilation?

 

But if there where to be two objects traveling at 0.6 c and at opposite directions. Then wouldn't one object see the other move away at 1.2 c?

[Tormod]

But if there where to be two objects traveling at 0.6 c and at opposite directions. Then wouldn't one object see the other move away at 1.2 c?

 

One thing Einstein postulated was that an object traveling at light speed would still see any lightbeam leaving it as traveling at light speed. This is because the speed of light is the same for all observers.

 

What makes it seem difficult to grasp is that when you consider two galaxies receding from each other at, say, 0.6c, it sounds intuitive to add up the speeds. But Einstein infered that the speed of light is the same for all observers in the universe. Thus they cannot see galaxies receding faster than the speed of light.

 

I think what will actually happen (someone please correct me if I'm mistaken) is that the galaxies' will fall outside of each other's observable horizon (or will eventually do so). Seen from Galaxy 1, Galaxy 2 will recede and then disappear - because the light from Galaxy 2 will never reach Galaxy 1 after that. There is nothing mystic about this, it follows the laws of physics.

[JoeRoccoCassara]

Many things can and have moved faster than light, like the speed of thought, and the expanding center of the big bang fire ball, and a space time annihilating pulse propelled space craft inside of a ripple in space time.

 

 

But a better question is, will we ever be able to produce the energy to move faster than light?

 

Not in our free country, if you have seen Dune, you would know that artificial/natural substances/primitive life forms could create men with the ability to manipulate the fabric of our universe, although it would take time, production, and propaganda that our free country just doesn't have.

[TheFaithfulStone]

:huh:

 

tfs

[InfiniteNow]

Many things can and have moved faster than light, like the speed of thought, and the expanding center of the big bang fire ball, and a space time annihilating pulse propelled space craft inside of a ripple in space time.

 

 

But a better question is, will we ever be able to produce the energy to move faster than light?

 

Not in our free country, if you have seen Dune, you would know that artificial/natural substances/primitive life forms could create men with the ability to manipulate the fabric of our universe, although it would take time, production, and propaganda that our free country just doesn't have.

 

Sorry champ. I respect your enthusiasm, but simply must call to attention the vast inaccuracies in your post. None of those things you listed have ever "moved faster than the speed of light."

 

The speed of thought idea you reference has even been discredited in this very thread (see posts #176, 180, 183).

 

Also, Dune is fiction. It's great fiction, but still fiction. It's your place to understand the difference between that and experience.

 

 

Cheers. :huh:

[JoeRoccoCassara]

This will be my first time to argue with some one, I think that this will be a long argument, it takes the brain 300 milliseconds to understand a picture, a fraction of a second, there called signals, or synapses, if you decide to move your arm, it takes less time for the signals to flex the muscles than it would for light to travel less distance than the signals did. Although its impossible to tell when some one sends their signals to move the muscles, there is still a possibility that they move much faster than light.

 

Dune is an exaduration of the real thing, the real thing is creating artificial bacteria that can slightly manipulate micro objects, and injecting them into a human embryo. Each new generation the embryo's will become more manipulative of objects, until they are able to curve the very fabric of our universe.

 

 

If there is an explosion the size of the big bang, the fireball would expand faster than light, do the math.

[InfiniteNow]

it takes the brain 300 milliseconds to understand a picture, a fraction of a second, there called signals, or synapses, if you decide to move your arm, it takes less time for the signals to flex the muscles than it would for light to travel less distance than the signals did.

Can you please provide some sort of empirical support for this claim?

 

You see, I've found MANY examples of contradictory evidence which states that the average nerve signal conduction speed is 50 meters/second. Here's one in .pdf:

http://wuphys.wustl.edu/ClassInfo/360/Experiments/Physics/Biopac/expNerve.pdf

 

Doing the math, you will see that

a) Speed of light = 300,000 meters/second

:eek2: Speed of nerve signal conduction = 50 meters/second

 

Therefore, the speed of light is 6,000 times faster than the speed of nerve signal conduction.

 

Although its impossible to tell when some one sends their signals to move the muscles,

Actually, it's not.

Methods of measuring brain and central nervous system activity

 

Dune is an exaduration of the real thing, the real thing is creating artificial bacteria

What is an artificial bacteria?

 

that can slightly manipulate micro objects,

Just what are you referencing? What's is the relevance of these "micro objects?"

 

and injecting them into a human embryo. Each new generation the embryo's will become more manipulative of objects, until they are able to curve the very fabric of our universe.

What objects? Manipulative how? You speak as if this is happening already and I'm a dunce for not seeing it, yet you have provided no evidence that this is anything more than fantasy. Where's the beef?

 

If there is an explosion the size of the big bang, the fireball would expand faster than light, do the math.

Uhhmmm... okay. The BB (a theory not proven either) represents the rapid expasion of the universe itself... of EVERYTHING. So, my question to you is, faster than light according to what perspective? There is no "outside of the universe."

 

 

The raindrops are unicorns crying and the wind is a leprechaun fart. :huh:

[JoeRoccoCassara]

Yet, it doesn't exist as a single entity, and the only speed we can associate with it, is the speed as written in the previous posts, 50m/s

 

 

Slower than light, much slower, but what about the big bang fireball

[JoeRoccoCassara]

"What is an artificial bacteria?"

 

Man made bacteria.

 

 

 

 

"Just what are you referencing? What's is the relevance of these "micro objects?"

 

The manipulating will merge as a human gene, the human will be able to manipulate objects like apples, bananas and water.

 

 

"You speak as if this is happening already and I'm a dunce for not seeing it, yet you have provided no evidence that this is anything more than fantasy. Where's the beef?"

 

It is possible to do.

 

"Uhhmmm... okay. The BB (a theory not proven either) represents the rapid expasion of the universe itself... of EVERYTHING. So, my question to you is, faster than light according to what perspective? There is no "outside of the universe."

 

The energy expanding from a condensed state.

[InfiniteNow]

Man made bacteria.

I love blue cheese.

 

The manipulating will merge as a human gene, the human will be able to manipulate objects like apples, bananas and water.

We can already do this. They're called thumbs.

 

It is possible to do.

You are still lacking bovine meat with your claim.

 

The energy expanding from a condensed state.

 

Oh, so you mean the energy from when water droplets form on the border of Rhode Island. :huh: