# tachyons

• 67 Replies
• 11461 Views

#### Jack

• 5179
##### Re: tachyons
« Reply #30 on: February 26, 2009, 12:04:33 PM »
I can't give you a specific number because any specific number will do, just as the standard equations for SR are valid for any chosen mass as long as you adjust energy and other values accordingly. You might as well ask for a specific mass for a regular particle.
Rest mass of a photon = 0. Not as hypothetical as the tachyon, doesn't it?

Ok. Let's be explicit: Your statement is wrong.
Really, so massless particles can go faster than the speed of light, while massive particles can accelerate past the speed of light?

Because that's only true for massive particles whose mass is a real number. If the mass is an imaginary number then the particle has to start out faster than c and can't slow down past c. See the issue?

Here, if you can actually read.
Quote
Relative to all inertial observers, massless particles travel at c. Relative to all inertial observers, massive particles (or any particles with mass) may approach c but never get to or past c.

#### cmdshft

• The Elder Ones
• 13129
• swiggity swooty
##### Re: tachyons
« Reply #31 on: February 26, 2009, 12:06:45 PM »

lol some people in this thread haven't got a clue about physics or relativity.

I teach university physics I have a PhD, admitedly in condensed matter physics.

A particle can travel faster than the speed of light if it has zero rest mass i.e. the mass of the particle at rest in ALL inertial frames of reference. Any particle that moves has a mass associated with it due to it's movement.

Some of the physics stated in this thread is shocking tbh.

I've been trying to explain this as well, but no one seems to get it.

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#### MotherNature

• 309
##### Re: tachyons
« Reply #32 on: February 26, 2009, 12:17:23 PM »
I can't give you a specific number because any specific number will do, just as the standard equations for SR are valid for any chosen mass as long as you adjust energy and other values accordingly. You might as well ask for a specific mass for a regular particle.
Rest mass of a photon = 0. Not as hypothetical as the tachyon, doesn't it?

Ok. Let's be explicit: Your statement is wrong.
Really, so massless particles can go faster than the speed of light, while massive particles can accelerate past the speed of light?

Because that's only true for massive particles whose mass is a real number. If the mass is an imaginary number then the particle has to start out faster than c and can't slow down past c. See the issue?

Here, if you can actually read.
Quote
Relative to all inertial observers, massless particles travel at c. Relative to all inertial observers, massive particles (or any particles with mass) may approach c but never get to or past c.

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

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#### JoshuaZ

• 351
##### Re: tachyons
« Reply #33 on: February 26, 2009, 12:46:02 PM »

lol some people in this thread haven't got a clue about physics or relativity.

I teach university physics I have a PhD, admitedly in condensed matter physics.

A particle can travel faster than the speed of light if it has zero rest mass i.e. the mass of the particle at rest in ALL inertial frames of reference. Any particle that moves has a mass associated with it due to it's movement.

Some of the physics stated in this thread is shocking tbh.

I don't think I've said anything wrong or contradicting what you've said. If I've said anything wrong in particular please let me know.

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#### MotherNature

• 309
##### Re: tachyons
« Reply #34 on: February 26, 2009, 12:53:15 PM »

lol some people in this thread haven't got a clue about physics or relativity.

I teach university physics I have a PhD, admitedly in condensed matter physics.

A particle can travel faster than the speed of light if it has zero rest mass i.e. the mass of the particle at rest in ALL inertial frames of reference. Any particle that moves has a mass associated with it due to it's movement.

Some of the physics stated in this thread is shocking tbh.

I don't think I've said anything wrong or contradicting what you've said. If I've said anything wrong in particular please let me know.

woops sorry I quoted the wrong person

#### Jack

• 5179
##### Re: tachyons
« Reply #35 on: February 26, 2009, 02:53:59 PM »
A particle can travel faster than the speed of light if it has zero rest mass i.e. the mass of the particle at rest in ALL inertial frames of reference.
So photons can travel faster than the speed of light?

Any particle that moves has a mass associated with it due to it's movement.
A photon can move without invariant mass, but with energy. You don't know what you're talking about.

Some of the physics stated in this thread is shocking tbh.
Says the "Ph.D professor" who doesn't even understand physics.

http://en.wikipedia.org/wiki/Rest_mass
And?

#### optimisticcynic

• 2200
##### Re: tachyons
« Reply #36 on: February 26, 2009, 06:11:06 PM »

lol some people in this thread haven't got a clue about physics or relativity.

I teach university physics I have a PhD, admitedly in condensed matter physics.

A particle can travel faster than the speed of light if it has zero rest mass i.e. the mass of the particle at rest in ALL inertial frames of reference. Any particle that moves has a mass associated with it due to it's movement.

Some of the physics stated in this thread is shocking tbh.
A. I would like to hear your complaints about anything I have said.
B. If a tachyon went by a galaxy would it curve towards the galaxy or away from it because of gravity
You can't outrun death forever
But you can sure make the old bastard work for it.

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#### MotherNature

• 309
##### Re: tachyons
« Reply #37 on: February 26, 2009, 06:24:01 PM »
A particle can travel faster than the speed of light if it has zero rest mass i.e. the mass of the particle at rest in ALL inertial frames of reference.
So photons can travel faster than the speed of light?

Any particle that moves has a mass associated with it due to it's movement.
A photon can move without invariant mass, but with energy. You don't know what you're talking about.

Some of the physics stated in this thread is shocking tbh.
Says the "Ph.D professor" who doesn't even understand physics.

http://en.wikipedia.org/wiki/Rest_mass
And?

Also I'm not a professor. I don't teach in America. I teach in the UK.

#### Jack

• 5179
##### Re: tachyons
« Reply #38 on: February 26, 2009, 06:29:42 PM »

Also I'm not a professor. I don't teach in America. I teach in the UK.
I feel sorry for your students.

#### Euclid

• 943
##### Re: tachyons
« Reply #39 on: February 26, 2009, 06:50:56 PM »
Um, Jack, I don't think you are getting the fact that tachyons are able to travel faster than the speed of light because they have an imaginary mass.  There is nothing inconsistent with SR about it.
Quote from: Roundy the Truthinessist
Yes, thanks to the tireless efforts of Euclid and a few other mathematically-inclined members, electromagnetic acceleration is fast moving into the forefront of FE research.

#### Jack

• 5179
##### Re: tachyons
« Reply #40 on: February 26, 2009, 06:53:44 PM »
I know that. I, however, is questioning MotherNature's credibility.

#### Euclid

• 943
##### Re: tachyons
« Reply #41 on: February 26, 2009, 06:55:14 PM »
Oh, I was referring to your debate with JoshuaZ.
Quote from: Roundy the Truthinessist
Yes, thanks to the tireless efforts of Euclid and a few other mathematically-inclined members, electromagnetic acceleration is fast moving into the forefront of FE research.

#### Jack

• 5179
##### Re: tachyons
« Reply #42 on: February 26, 2009, 07:13:51 PM »
Yeah, I was a little too rushy there. I was merely trying to question the existence of such particles.

#### optimisticcynic

• 2200
##### Re: tachyons
« Reply #43 on: February 26, 2009, 07:16:37 PM »
wouldn't it just stretch space time out the opposite direction. Also matters with a positive mass is attracted to space time that has been warped in that direction tachyons stretch it in the other way so wouldn't it be repelled matters way of stretching it.

Mass creates gravity. Gravity stretches space-time. That's why if you were to fall into the gravity well of a black hole, an outside observer would see your body slow down to a near standstill as you approach it's event horizon. It takes longer and longer to reach the next point. An object such as a tachyon with negative mass would possibly shrink space-time, and could be why it propels through space at FTL speeds. It's basically shrinking the space-time in front of it, and stretching out space-time behind it as it moves.

It's also theorized (this is where Star Trek actually stole the idea from) that if you could somehow make a tachyon "field" you would effectively negate the mass of anything inside this field, which would allow the object to be exempt from GR and SR altogether and move along at FTL speeds. Although, Star Trek adds that it simply shifts the mass into subspace, but that's just to be special I believe.
The fact something seems to slow down as it approaches a black hole has nothing  to do with stretching of space time. it has to do with what happens to the light in the gravity.
So if it did warp space time one way it should be attracted to things that warp it the same way and repelled by thing that warp it the opposite way. So it should still be repelled by the gravity of are galaxy.

No. Please educate yourself on newtonian physics and general relativity and how the two interact with one another as far as black holes and gravity are concerned.
Did you read the source? it agreed with what I said about seeing something falling into a black hole. would you like me to go and find other sources that also agree with me. I believe a brief history of time also mentions it . or would you rather keep saying I don't understand the subject?
You can't outrun death forever
But you can sure make the old bastard work for it.

#### cmdshft

• The Elder Ones
• 13129
• swiggity swooty
##### Re: tachyons
« Reply #44 on: February 26, 2009, 07:37:24 PM »
You're wrong because I am not talking about light, I am talking about space-time. The black hole metaphor was an example, you went off on the wrong tangent with it. So again, please educate yourself.

#### optimisticcynic

• 2200
##### Re: tachyons
« Reply #45 on: February 26, 2009, 07:51:11 PM »
You're wrong because I am not talking about light, I am talking about space-time. The black hole metaphor was an example, you went off on the wrong tangent with it. So again, please educate yourself.
I explained why an object appears to slow down as it approaches the event horizon. It will still go through the event horizon but to the out side observer they never reach the event horizon. If that doesn't demonstrate what you were talking about then you should have picked a better example.
You can't outrun death forever
But you can sure make the old bastard work for it.

#### cmdshft

• The Elder Ones
• 13129
• swiggity swooty
##### Re: tachyons
« Reply #46 on: February 26, 2009, 08:01:41 PM »
You're wrong because I am not talking about light, I am talking about space-time. The black hole metaphor was an example, you went off on the wrong tangent with it. So again, please educate yourself.
I explained why an object appears to slow down as it approaches the event horizon. It will still go through the event horizon but to the out side observer they never reach the event horizon. If that doesn't demonstrate what you were talking about then you should have picked a better example.

Again, not what we're discussing. The example was used to explain the idea of expansion and compression of space-time.

#### optimisticcynic

• 2200
##### Re: tachyons
« Reply #47 on: February 26, 2009, 08:11:36 PM »
You're wrong because I am not talking about light, I am talking about space-time. The black hole metaphor was an example, you went off on the wrong tangent with it. So again, please educate yourself.
I explained why an object appears to slow down as it approaches the event horizon. It will still go through the event horizon but to the out side observer they never reach the event horizon. If that doesn't demonstrate what you were talking about then you should have picked a better example.

Again, not what we're discussing. The example was used to explain the idea of expansion and compression of space-time.
It was a bad example. You are the one that brought up black holes and watching how it slows down as it approaches the event horizon. your reason for this phenomenon was wrong. You said my correction was wrong. I am just defending my correction.
You can't outrun death forever
But you can sure make the old bastard work for it.

#### cmdshft

• The Elder Ones
• 13129
• swiggity swooty
##### Re: tachyons
« Reply #48 on: February 26, 2009, 08:31:48 PM »
You're wrong because I am not talking about light, I am talking about space-time. The black hole metaphor was an example, you went off on the wrong tangent with it. So again, please educate yourself.
I explained why an object appears to slow down as it approaches the event horizon. It will still go through the event horizon but to the out side observer they never reach the event horizon. If that doesn't demonstrate what you were talking about then you should have picked a better example.

Again, not what we're discussing. The example was used to explain the idea of expansion and compression of space-time.
It was a bad example. You are the one that brought up black holes and watching how it slows down as it approaches the event horizon. your reason for this phenomenon was wrong. You said my correction was wrong. I am just defending my correction.

It was not a bad example at all, you're trying to break it down in a way that isn't applicable to the overall topic of how a tachyon manipulates space-time to achieve FTL speeds.

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#### MotherNature

• 309
##### Re: tachyons
« Reply #49 on: February 27, 2009, 05:52:57 AM »

Also I'm not a professor. I don't teach in America. I teach in the UK.
I feel sorry for your students.

If a particle is moving it cannot be massless.

#### Jack

• 5179
##### Re: tachyons
« Reply #50 on: February 27, 2009, 12:28:03 PM »
When we say mass, we mean invariant mass, not relativistic mass. Please replace relativistic mass with energy. A particle can move and still remain massless, while its energy continues to increase due to its motion.

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#### MotherNature

• 309
##### Re: tachyons
« Reply #51 on: February 27, 2009, 01:50:33 PM »
When we say mass, we mean invariant mass, not relativistic mass. Please replace relativistic mass with energy. A particle can move and still remain massless, while its energy continues to increase due to its motion.

Well in that case you should be discussing the scalar field. Since the imaginary rest mass is not a physical quantity.

/sigh

edit: also if a particle has any kind of movement it HAS to have mass (relativistic). The two are linked.
« Last Edit: February 27, 2009, 02:18:14 PM by MotherNature »

#### Jack

• 5179
##### Re: tachyons
« Reply #52 on: February 27, 2009, 04:24:17 PM »
edit: also if a particle has any kind of movement it HAS energy. The two are linked.
Fixed.

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#### MotherNature

• 309
##### Re: tachyons
« Reply #53 on: February 27, 2009, 04:37:30 PM »
edit: also if a particle has any kind of movement it HAS energy. The two are linked.
Fixed.

Really?

No seriously.

Really?

#### Jack

• 5179
##### Re: tachyons
« Reply #54 on: February 27, 2009, 05:14:36 PM »
Yeah.

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#### MotherNature

• 309
##### Re: tachyons
« Reply #55 on: February 27, 2009, 05:24:03 PM »
Yeah.

come on you can do better than that.

I am genuinly perplexed.

#### optimisticcynic

• 2200
##### Re: tachyons
« Reply #56 on: February 27, 2009, 07:13:44 PM »
You're wrong because I am not talking about light, I am talking about space-time. The black hole metaphor was an example, you went off on the wrong tangent with it. So again, please educate yourself.
I explained why an object appears to slow down as it approaches the event horizon. It will still go through the event horizon but to the out side observer they never reach the event horizon. If that doesn't demonstrate what you were talking about then you should have picked a better example.

Again, not what we're discussing. The example was used to explain the idea of expansion and compression of space-time.
It was a bad example. You are the one that brought up black holes and watching how it slows down as it approaches the event horizon. your reason for this phenomenon was wrong. You said my correction was wrong. I am just defending my correction.

It was not a bad example at all, you're trying to break it down in a way that isn't applicable to the overall topic of how a tachyon manipulates space-time to achieve FTL speeds.
Yes I know that time slows down when you are in gravity but that is not why objects come to a near stand still near the event horizon of a black hole. They don't stop next to the event horizon it just appears they do.
You can't outrun death forever
But you can sure make the old bastard work for it.

#### cmdshft

• The Elder Ones
• 13129
• swiggity swooty
##### Re: tachyons
« Reply #57 on: February 27, 2009, 08:54:12 PM »
You're wrong because I am not talking about light, I am talking about space-time. The black hole metaphor was an example, you went off on the wrong tangent with it. So again, please educate yourself.
I explained why an object appears to slow down as it approaches the event horizon. It will still go through the event horizon but to the out side observer they never reach the event horizon. If that doesn't demonstrate what you were talking about then you should have picked a better example.

Again, not what we're discussing. The example was used to explain the idea of expansion and compression of space-time.
It was a bad example. You are the one that brought up black holes and watching how it slows down as it approaches the event horizon. your reason for this phenomenon was wrong. You said my correction was wrong. I am just defending my correction.

It was not a bad example at all, you're trying to break it down in a way that isn't applicable to the overall topic of how a tachyon manipulates space-time to achieve FTL speeds.
Yes I know that time slows down when you are in gravity but that is not why objects come to a near stand still near the event horizon of a black hole. They don't stop next to the event horizon it just appears they do.

No, that's all relative.

#### optimisticcynic

• 2200
##### Re: tachyons
« Reply #58 on: February 27, 2009, 08:57:33 PM »
You can't outrun death forever
But you can sure make the old bastard work for it.

#### cmdshft

• The Elder Ones
• 13129
• swiggity swooty
##### Re: tachyons
« Reply #59 on: February 27, 2009, 09:26:19 PM »
Are you dense?

Dude, EVERYTHING in this universe is done in inertial frames of reference.