faster than light?

[thenumbersix]

Re: faster than light?

so achieving the speed of light is an illusion ! How ever much energy we pump in we will still be at a standstill.

In this case.. At what point, when travelling away from the Earth, does it stop being a point of reference and what can we expect of the perceived distance to the next star at this time ?

 

[Harte]

Re: faster than light?

TN6,

<div class='quotetop'>QUOTE(\"thenumbersix\")</div>

so achieving the speed of light is an illusion ! How ever much energy we pump in we will still be at a standstill.[/b]

No, you will be moving at some velocity relative to your original reference frame (where you were before you began to move.) You cannot acheive lightspeed as measured from any reference frame though. If you are moving at 99% of C, then that's what someone in your original reference frame will measure your speed to be. If, at this time, you shine a light at the wall toward your direction of travel, you will see that the light moves at the speed of light because you are your own reference frame. Some guy not moving with your speed that is positioned outside your ship looking in (say a guy with a very good telescope back on Earth) will also see your beam moving at the speed of light C. Not C+99% C like you might think.

<div class='quotetop'>QUOTE(\"thenumbersix\")</div>

In this case.. At what point, when travelling away from the Earth, does it stop being a point of reference and what can we expect of the perceived distance to the next star at this time ? [/b]

If you left from the earth, then the earth is your original reference frame. When you begin to move relative to the Earth, then you have created a new (your own) reference frame. Nothing will change the distance (perceived or real) to the next star. Constriction of length only occurs in your reference frame, and then only when observed from outside your reference frame (the guy with the telescope.)

Einstein used a good example to illustrate how we make our own reference frame. Apparently he lived at some time near a canal that was connected to the ocean. You could sit on the bank of the canal and watch waves from the ocean move up the canal from right to left. The waves moved at a slow pace that could be matched by jogging next to the canal. He noticed that, as he jogged in the direction that the waves moved, if he looked only at the water surface, it appeared to him that the canal water was experiencing a series of equidistant standing waves. If he stopped, the waves appeared to move from the right to the left. Which perception is more real? The are equal.

Harte

 

[Felic--]

Re: faster than light?

There is a theoretical method for travelling faster than light involving spacetime.

- Position a craft in a certain area of space.
- Distort the spacetime at the fore of the craft to contract.
- Distort the spacetime at the aft of the craft to expand.

This will create and arrowhead shape field of spacetime around the craft. According to super relativity theory, the field should 'slip' through the rest of spacetime. Because the accepted physical constants do not neccessarily apply in quantum, the field is likely to be capable of travelling faster than the speed of light. The problem is, the exact speed it will go at is completely unpredictable.

 

[thenumbersix]

Re: faster than light?

No, you will be moving at some velocity relative to your original reference frame (where you were before you began to move.) You cannot acheive lightspeed as measured from any reference frame though. If you are moving at 99% of C, then that's what someone in your original reference frame will measure your speed to be. If, at this time, you shine a light at the wall toward your direction of travel, you will see that the light moves at the speed of light because you are your own reference frame. Some guy not moving with your speed that is positioned outside your ship looking in (say a guy with a very good telescope back on Earth) will also see your beam moving at the speed of light C. Not C+99% C like you might think.

This is just a means of visualisation though, it does not necessarily stand up in the real world.

The point of reference use is simply to illustrate a calculation. Everything in the universe has to be our real point of reference. If we move toward another star then we move away from the Earth and toward the other star, they are both points of reference. As is everything else in existence as we must be moving in one direction or another relative to them.

c being constant is more to do with energy and mass conversions. Wasn't he saying that when converting mass to energy or vice versa that mass and energy can change but light can't ? You couldn't contain the energy from a nuclear detenation and change the speed of light locally (or could you)...

Tenshi, if your craft reaches infinite mass, doesn't this include your fuel tank which will also gain infinite mass ! There's your infinte energy source.

I read some time ago that this would be the best way to traverse large distances. If you acheive infinte mass at the speed of light (or near to) then you are everywhere in the Universe at once, all you need do is slow yourself down but aim for the target point the other side of the universe. With infinite mass you are already there. Sounds a bit like the improbability drive....

 

[Harte]

Re: faster than light?

<div class='quotetop'>QUOTE(\"thenumbersix\")</div>

This is just a means of visualisation though, it does not necessarily stand up in the real world.

The point of reference use is simply to illustrate a calculation. Everything in the universe has to be our real point of reference. If we move toward another star then we move away from the Earth and toward the other star, they are both points of reference. As is everything else in existence as we must be moving in one direction or another relative to them. [/b]

It absolutely does stand up in the real world. It is the real world. This is the very basis for time dilation, which has been measured precisely multiple times in the past and always has matched exactly Einstein's predictions. In fact, time dilation is used on almost a daily basis in particle physics. It enables scientists to observe properties of particles moving at high speeds that they would not have been able to observe if time dilation did not extend the life of these particles.

When you say point of reference, you are talking about a different thing than I am. I spoke of the reference frame. That is everything that is traveling with you, not the place you are coming from or going to.

<div class='quotetop'>QUOTE(\"thenumbersix\")</div>

c being constant is more to do with energy and mass conversions. Wasn't he saying that when converting mass to energy or vice versa that mass and energy can change but light can't ? You couldn't contain the energy from a nuclear detenation and change the speed of light locally (or could you)... [/b]

C is absolutely constant, a fact proven in the Michelson-Morley experiment that also showed that there exists no "ether". Special Relativity does not predict C to be a constant, it assumes it. It is a postulate in Special Relativity that C is constant. Every prediction of Special Relativity is a result of this fact. Indeed, the entire theory can be deduced from C being constant. C will always be measured to be the same no matter which reference frame you are in, whether you are moving with the flashlight or whether you are standing still and the flashlight is moving past you.

<div class='quotetop'>QUOTE(\"thenumbersix\")</div>

Tenshi, if your craft reaches infinite mass, doesn't this include your fuel tank which will also gain infinite mass ! There's your infinte energy source.[/b]

Again, infinite fuel does not equal infinite thrust. As your mass approaches infinity, your engine's thrust (which is not subject to relativistic effects) still has to accelerate you. Your thrust is finite, your mass infinite, which one prevails? Can an ant make a moving car speed up by pushing on it?

Harte

 

[MadIce]

Re: faster than light?

There is a problem with thinking that mass increases when the volicity increases. Even teachers tell you that mass increases when the volicity increases. You can even read it in books. The problem is... It doesn't work that way.
<div class='quotetop'>QUOTE(\"\"Gary Oas\"\")</div>

There is one concept that has been ingrained into the collective mindset of not only lay-people but also many working physicists. This is the notion of relativistic mass; a moving object?s mass increases with velocity with respect to an observer considered to be at rest [...][/b]

This is from an article recently published at arXiv.org. Here is the abstract:
<div class='quotetop'>QUOTE(\"\"Gary Oas\"\")</div>

The concept of velocity dependent mass, relativistic mass, is examined and is found to be inconsistent with the geometrical formulation of special relativity. This is not a novel result; however, many continue to use this concept and some have even attempted to establish it as the basis for special relativity. It is argued that the oft-held view that formulations of relativity with and without relativistic mass are equivalent is incorrect. Left as a heuristic device a preliminary study of first time learners suggest that misconceptions can develop when the concept is introduced without basis. In order to gauge the extent and nature of the use of relativistic mass a survey of the literature on relativity has been undertaken. The varied and at times self-contradicting use of this concept points to the lack of clear consensus on the formulation of relativity. As geometry lies at the heart of all modern representations of relativity, it is urged, once again, that the use of the concept at all levels be abandoned.[/b]

On the Abuse and Use of Relativistic Mass by Gary Oas.

The author also investigates a large number of publications in which this is told. Maybe boring, but he published a large list in the paper below.
<div class='quotetop'>QUOTE(\"\"Gary Oas\"\")</div>

A lengthy bibliography of books referring to special and/or general relativity is provided to give a background for discussions on the historical use of the concept of relativistic mass.[/b]

On the Use of Relativistic Mass in Various Published Works by Gary Oas.

In the 70s people tried to get rid of that misconception. For a while they succeeded. For some reason the error is back. In the year of Einstein's 100th anniversary the author thought it would be a good idea to highlight it once again. I think these are must reads for anyone involved in physics and who post on a time travel forum like this.

 

[PhantomLord]

Re: faster than light?

On those shows they show on Discovery about traveling in space, they talk about a theory of space travel with nuclear purpolsion. Basically the ship has a huge parachute sail in front of it and you launch a mini nuke into it and the blast is used as the excelleration. I forget how fast they think they could go but I think they said in theory you could from Earth to Mars in Days rather then months using this.

But thats still a way off even by early estimates (plus we can just imagine how fun it would be when NASA asks congress for a few billion to test out that baby if its ever made).

 

[thenumbersix]

Re: faster than light?

<div class='quotetop'>QUOTE(\"Harte\")</div>

?
When you say point of reference, you are talking about a different thing than I am. I spoke of the reference frame. That is everything that is traveling with you, not the place you are coming from or going to.
Harte[/b]

Uh ? So...

<div class='quotetop'>QUOTE(\"Harte\")</div>

?
No, you will be moving at some velocity relative to your original reference frame (where you were before you began to move.)
Harte[/b]

Earth is our reference frame, that we just left, but is travelling with us ?? I'm confused.

I sitll want to see what happens when we leave the presence of a gravity well, I think there will be no space or time there so traversing the expanses will be instantaneous, but then I don't have a space ship to prove it either

 

[gomp]

Re: faster than light?

<div class='quotetop'>QUOTE(\"nate\")</div>

I was thinking, if you send a space shuttle into space, get it to go 20,000mph and stop the thrust from the engines, wouldnt you continue to go 20,000mph? If so then why cant you thrust and continue to use the engines to get past the speed of light if you had an unlimited amount of fuel?[/b]

I am tiered and dident read the whole thread so if some one else posted this then oops
Well because the faster you move the slower time moves for you and the more mass you have, you would in fact need an infinite amount of fuel in order to push your self faster than the speed of light, the bummer part is if you ever did that, you mass would reach a value equal to infinnaty, and the universe would colapse around you. and you would be made fun of forever cause your the jack ass that filled his gass tank up to and infinite amount and distroyed the universe

 

[Harte]

Re: faster than light?

<div class='quotetop'>QUOTE(\"thenumbersix\")</div>

Earth is our reference frame, that we just left, but is travelling with us ?? I'm confused.[/b]

TN6,
I certainly don't mean to confuse you. I think the pertinant point you are missing is here in what I previously said:
<div class='quotetop'>QUOTE(\"Harte\")</div>

If you left from the earth, then the earth is your original reference frame. When you begin to move relative to the Earth, then you have created a new (your own) reference frame. [/b]

You create a new reference frame when you begin to move with respect to your original reference frame (the Earth). You have no motion with respect to your current reference frame. It travels with you. If you look out a window of your spaceship at a passing planet, it is true to say "I am moving past that planet. It is equally true to say "That planet is moving past me." The second statement illustrates what I mean by no motion with respect to your current reference frame.

I included this example in a previous post to try and cut through any confusion:

<div class='quotetop'>QUOTE(\"Harte\")</div>

Einstein used a good example to illustrate how we make our own reference frame. Apparently he lived at some time near a canal that was connected to the ocean. You could sit on the bank of the canal and watch waves from the ocean move up the canal from right to left. The waves moved at a slow pace that could be matched by jogging next to the canal. He noticed that, as he jogged in the direction that the waves moved, if he looked only at the water surface, it appeared to him that the canal water was experiencing a series of equidistant standing waves. If he stopped, the waves appeared to move from the right to the left. Which perception is more real? They are equal.[/b]

Sitting on the bank of the canal, Einstein shared the reference frame of anything else around him that was motionless. Once he began to jog, he created a new reference frame for himself. The fact that these two reference frames are not the same is illustrated by what he sees the waves in the canal doing when he is in one reference frame and then in the other.

Think of traveling on a train at 60 mph. If you get up and walk down the aisle at 5 mph, it looks to everyone sitting on the train that you are moving at 5 mph. Someone on the ground outside the train looking in would see you walking at 65 mph. To you, it appears that you are still and the interior of the train is moving past you at 5 mph.

<div class='quotetop'>QUOTE(\"thenumbersix\")</div>

I sitll want to see what happens when we leave the presence of a gravity well, I think there will be no space or time there so traversing the expanses will be instantaneous, but then I don't have a space ship to prove it either [/b]

Good luck finding a place outside any gravity well.

Harte