Weird physics question

[the_tyrant]

I was sitting there, and i just had a weird idea
imagine 2 points a and b
the distance between a and b takes light 1 minute(or any amount of time) to travel
there is a tense piece of string connecting point a and b
hypothetically, if a light was shined from point a to point b and that the string was pulled at point a at the same time, what would we felt at point b first?
the light or the pull on the string?

or a better restatement would be, does light travel faster, or does a piece of mass travel faster?

edit: Rephrasing the question: solid mass vs light, what would be felt on the other side faster?

[Spike88]

I'm pretty sure the string will not travel at the speed of light, unless it has Star Wars light-speed drives :P.


Also if it takes 1 minute for the light to travel, the string will most likely fall limp before it can even reach the end. Unless it was in a vacuum, but even then light travels fastest.


Edit: And thinking about it. Nothing can go the speed of light(besides Light) anyways.

[TLAM Strike]

Originally Posted by Spike88

Edit: And thinking about it. Nothing can go the speed of light(besides Light) anyways.

Nothing can accelerate faster than light. Objects already moving faster than light can exist.

[Gargamel]

Originally Posted by TLAM Strike

Nothing can accelerate faster than light. Objects already moving faster than light can exist.

Close, but nothing can accelerate to the speed of light. Using relativity, it requires an infinite amount of energy (more than is in the known universe) to accelerate an object to the speed of light. The faster you go, the more mass an object has, requiring more energy to go faster.

An object already going light speed, could in theory stay at that speed if they don't encounter any drag. In that same theory, objects could go faster than the speed of light, IF they began that way. But where would such objects come from?

[Diopos]

Originally Posted by Gargamel

...
An object already going light speed, could in theory stay at that speed if they don't encounter any drag. In that same theory, objects could go faster than the speed of light, IF they began that way. But where would such objects come from?

The future ?



.

[tater]

For a vibration in the string, the speed depends on the mass and tension on the string (it's a transverse wave). It will be less than c.

For a pull, the string will stretch, and then the wave propagates like sound (longitudinal wave) and will move at the speed of sound in the media.

BTW, doesn't matter if you replace the string with a neutronium rod. Still takes time (more than light) to propagate.

[TLAM Strike]

Originally Posted by Diopos

The future ?



.

Actually you are right. As I understand it Tachyons travel back in time as they travel faster than c.

[UnderseaLcpl]

Originally Posted by TLAM Strike

Nothing can accelerate faster than light. Objects already moving faster than light can exist.

Granted, I'm no expert on physics, but I disagree - at least until you can explain it.

The way it was explained to me is that objects travelling at relativistic speeds undergo corresponding shifts in mass (as gargamel states), as well as relative time and dimension. Even if you somehow had two particles of anything approaching each other at the speed of light, their speed, in any frame of reference, even when added together, is still c.

--------------------------------------------

As far as the string question goes, the answer is, quite definitevely, that the light would reach its destination long before the molecules in the string resonated from one end to the other. Atoms have mass, and the distance atoms in anything must travel before repelling each other (once energy is imparted) is quite far in terms of scale.

The effect of plucking a string, no matter how taut, would still require the acceleration of every atom, and the force transmitted would decrease with distance travelled, so the light would get there first.

[Buddahaid]

If the signal was a wave. I'm saying what of a hypothetical string that has no mass, and no elasticity, and is moved as one massless length allowing binary language over limitless distance. No mass requires a pure energy object of some form that is imune to time.

Not for me to to proof!

[Raptor1]

Originally Posted by UnderseaLcpl

Granted, I'm no expert on physics, but I disagree - at least until you can explain it.

The way it was explained to me is that objects travelling at relativistic speeds undergo corresponding shifts in mass (as gargamel states), as well as relative time and dimension. Even if you somehow had two particles of anything approaching each other at the speed of light, their speed, in any frame of reference, even when added together, is still c.

It would be impossible for ordinary matter to travel at speeds greater than light speed, because the energy required to accelerate anything with mass to c is infinite. However, there are (theoretical) particles that always travel faster than light, and would similarly require an infinite amount of energy to slow down to light speed.

[TLAM Strike]

Originally Posted by UnderseaLcpl

Granted, I'm no expert on physics, but I disagree - at least until you can explain it.

Just google 'Tachyons'

I'll leave it at that because everything beyond that makes my head hurt.

[Gargamel]

Two ways to look at it:

1) Like sound under water, the energy in the string has a speed through a medium. It is slower than light. Hence we will see the light first.

or

2) The string can be considered a solid object when stretched to its maximum, ie no more stretch is possible. So when one end is pulled, the other end immediately moves too, and is therefore 'faster' than light. But this is not truly going faster than light, as nothing is moving from end to another, it's just an object beginning to move.

[Buddahaid]

Originally Posted by Gargamel

Two ways to look at it:

1) Like sound under water, the energy in the string has a speed through a medium. It is slower than light. Hence we will see the light first.

or

2) The string can be considered a solid object when stretched to its maximum, ie no more stretch is possible. So when one end is pulled, the other end immediately moves too, and is therefore 'faster' than light. But this is not truly going faster than light, as nothing is moving from end to another, it's just an object beginning to move.

Ah, but the cause and effect is then instantanious and faster than light. FTL communication via the cans and string?

[Gargamel]

Originally Posted by Buddahaid

Ah, but the cause and effect is then instantanious and faster than light. FTL communication via the cans and string?

No, because then you are in situation 1, where energy is traveling along the string in a wave.

What is 'possible', though, is to build a 'stick' of great length, but it's internal components must be completely static, and then you could kind of swing it back and forth and do a morse code over great distances. But there are two problems with this:

1) For this to be faster and more practical than light speed transmissions, ie radio waves and the like, the 'stick' would have to be of immense length. Off the top of my head, the minimum would have to be something like the distance from Jupiter to the sun, or Earth if you like, around 5-6 AU (500,000,000 miles or so). This alone makes it impractical to build and maintain, let alone finding the energy to move such a mass, and then stop it after only a few inches of movement.

2) Even the electron bonds of the component molecules are not static, and have some give to them. Thus you would get some accordion type effect within it's structure. Thus, it would not be a solid object, but a string transmitting waves.

This type of transmission could only be of the morse code type, 1's and 0's, complex data streams would be practically impossible.

Nothing is technically moving faster that light, aside from the information contained in a forward/back position.

[Buddahaid]

1 and 0 makes for binary language. It's then a question of frequency for the very long string.