Lightspeed

[Achilles]

Or possibly that you cannot find any flaws?

When it's Solipsism vs. Reason, reason always loses. Doesn't make Solipsism correct, it only makes the fight unfair.

 

The phenomenal, being phenomenal, cannot be said with certainty to be noumenal without investing an element of faith in it. That is both evidence and the products of theory. And any theory without evidence is unsubstantiated and therefore unworthy of being supported.

Evidence is meaningless if perception is given no value. I find the argument to be hypocritical and unable to support its own weight, but successfully pointing that out requires breaking the circular logic of the philosophy in question.

 

I never said I believed this junk.

FWIW, I've never really been convinced that you did, hence why I've been unable to figure out why you would adopt such positions in the first place

[Darth InSidious]

When it's Solipsism vs. Reason, reason always loses. Doesn't make Solipsism correct, it only makes the fight unfair.

How so? I could say the same about faith vs. reason. Reason may win, but that doesn't make it right. It just means that the fight is between chalk and cheese.

Evidence is meaningless if perception is given no value. I find the argument to be hypocritical and unable to support its own weight, but successfully pointing that out requires breaking the circular logic of the philosophy in question.

Could you extrapolate?

 

FWIW, I've never really been convinced that you did, hence why I've been unable to figure out why you would adopt such positions in the first place

IIRC, I was originally trying to prove that your position required an input of faith/alternative synonym.

[tk102]

Lightspeed blows my mind. The stars that we see are not the stars of the present tense, but the stars from the past, their light just now arriving. The sun that we see is the sun from 8 minutes ago. Even the person in the same room as you is not the person of the present tense, but the person from a tiny fraction of a second ago. The only place that the present really exists is at distance=0. And so every point in the universe has its own present tense, and any phenomenon that occurs anywhere other than at that point, occurred in the past. link

[Achilles]

Lightspeed blows my mind. The stars that we see are not the stars of the present tense, but the stars from the past, their light just now arriving. The sun that we see is the sun from 8 minutes ago. Even the person in the same room as you is not the person of the present tense, but the person from a tiny fraction of a second ago. The only place that the present really exists is at distance=0. And so every point in the universe has its own present tense, and any phenomenon that occurs anywhere other than at that point, occurred in the past. link

@DI: I've posted my response to your post in the Atheism/Theism thread (or the Theism/Atheism thread...I can't remember which title is correct ).

 

@teekay: I agree with most of that except that "present" doesn't really exist. It's entirely conceptual, as is the future.

 

Interestingly, the 8 minutes that it takes light to travel from the sun to the earth was the catalyst of Einstein's theory of relativity. Using Newton's model, if the sun magically disappeared, then all of the planets would simultaneously abandon their orbit and begin drifting off into space. However it was also commonly accepted that nothing could travel faster than the speed of light. Therefore if Newton's model was correct, then in the above scenario, gravity would be traveling faster than light, which troubled Einstein.

 

From that he developed a theory of relativity which introduced space-time. Using the model provided by the new theory in the same scenario, the planets would still leave their orbit if the sun magically disappeared and amazingly would do so in accordance with the speed of light. In other words, if the sun disappeared, the earth would not leave it's orbit until the ripple in space-time reached us - exactly 8 minutes later.

 

ToR also predicted the existence of black hole (which we have found), dark matter (which we have found), and distant light bending around heavy stars (which we have observed).

 

So ToR's replacement is going to have to be truly spectacular indeed.

 

ADDED BY EDIT:

Whoops, looks like I may have remember the story a little (ok, a lot) incorrectly. The example is still valid, but apparently I mistook its relevance in Einstein's initial work on ToR. Here is a fun youtube clip which illustrates the example I outlined above.

 

Note: The narrator sounds like a total toolbox, but he's actually a prominent quantum physicist. Go figure.

[swfan28]

Originally Posted by Achilles

The theory of relativity does an exceptional job of explaining a great deal about the mechanics of our universe (on a non-quantum scale). In order to accomplish FTL travel, relativity would have to be replaced with another theory that offers just as good, if not better, explanations and doesn't place a "speed limit" on the universe.

Unfortunately I find it hard to imagine that happening. The replacement theory must be such that it's predictions are similar to those of theory of relativity on a non-quantum scale. For example Newton's theory of gravitation is a linearization of the general theory of relativity. I find it hard to believe that an "extension" for the theory of relativity would not contain the "speed limit" but I suppose there are examples of other even harder to believe things that have been proven correct in modern physics.

 

This is also why I believe faster than light travel to be truly impossible. Wormholes on the other hand are another matter. They are so far an unconfirmed prediction of the general theory of relativity and were believed to be too unstable to ever permit traveling through them. Recent hypothesis of dark energy, which is believed to be the reason why expansion of the universe seems to be accelerating, may also make more stable wormholes possible. At least in theory. There is of course no physical proof of this.

Originally Posted by Achilles

The theory of relativity is just as sound as electron theory and gravitational theory. Don't let the word "theory" fool you. If they theory of relativity were simply based on a few mathematical models, then I might be inclined to think that it's perch is unstable. However it, like all commonly accepted scientific theories, has the ability to make predictions and has is confirmed when evidence is found that corroborates those predictions.

Agreed. The entire theory of relativity is based on single principle: The laws of physics are unchanged regardless of the observer's state of motion. It was developed after the speed of light in vacuum was measured to be a constant regardless of the observer's motion. The resulting theory made lot of predictions and astronomers have found a lot of evidence that corroborates them since then. Examples include gravitational lens effects, black holes, relativistic effect that the mass of the Sun has on the orbit of Mercury and so on.

Originally Posted by Darth InSidious

Those are still just theories, and evidence, as well as results of the theory, being phenomenal, are largely irrelevant.

 

Gravity may exist or may not. No one can say for certain.

Now that is a strange thought. All theories of physics are mathematical models based on observations made of the universe around us. The phenomenon we call gravity clearly does exist. We all perceive it's effects and so far the theory of relativity comes closest to describe that effect. Even though it seems to fail in doing so in subatomic scale... What is gravity on the other hand has not been fully answered yet. Is the effect of gravity transmitted by particles called gravitons or is it "simply" a property of space-time to curve that way around particles with mass or is it something nobody has even thought of yet? Of all four forces of nature gravity is the least explained so far.

Originally Posted by Darth InSidious

The phenomenal, being phenomenal, cannot be said with certainty to be noumenal without investing an element of faith in it. That is both evidence and the products of theory. And any theory without evidence is unsubstantiated and therefore unworthy of being supported.

I fail to understand this argument. If a mathematical model that is a theory of physics is found to describe a phenomenon accurately then the theory is applicable.

Originally Posted by tk102

Lightspeed blows my mind. The stars that we see are not the stars of the present tense, but the stars from the past, their light just now arriving. The sun that we see is the sun from 8 minutes ago. Even the person in the same room as you is not the person of the present tense, but the person from a tiny fraction of a second ago. The only place that the present really exists is at distance=0. And so every point in the universe has its own present tense, and any phenomenon that occurs anywhere other than at that point, occurred in the past. link

Fascinating isn't it? With powerful telescopes we can actually gaze at the universe as it was billions of years in the past.

Originally Posted by Achilles

I agree with most of that except that "present" doesn't really exist. It's entirely conceptual, as is the future.

Well... I would argue that present and future do exist but they depend on the observer. What does not exist is simultaneity. Two distant events that look simutaneous to one observer might not look so for another due to the finiteness of the lightspeed.

[Achilles]

Fascinating isn't it? With powerful telescopes we can actually gaze at the universe as it was billions of years in the past.

on the Ultra Deep Field. Enjoy!

[SithRevan]

I think I may have to disagree with Achilles, I think it is more plausable then impossible. We just haven't figured it out yet. I see it this way, they said when we were trying to split the atom it was impossible, they said when we were trying to build airplanes and jets that it was impossible, and they said that mapping the Human Genome was impossible... but as you all can see most of those things are now possible and one of those things is currently being done. I feel that one of these days when we are actually ready to understand the concept of faster-then-light travel then and only then will we be able to make the thought of it being impossible disappear.

[swfan28]

Originally Posted by SithRevan

I think I may have to disagree with Achilles, I think it is more plausable then impossible. We just haven't figured it out yet. I see it this way, they said when we were trying to split the atom it was impossible, they said when we were trying to build airplanes and jets that it was impossible, and they said that mapping the Human Genome was impossible... but as you all can see most of those things are now possible and one of those things is currently being done. I feel that one of these days when we are actually ready to understand the concept of faster-then-light travel then and only then will we be able to make the thought of it being impossible disappear.

Those things you mentioned were only thought impossible to achieve with current technology, not theoretically impossible. The difference in traveling faster than light is that the theory of relativity clearly places a speed limit on particles with mass which means that accelerating past lightspeed is also theoretically impossible.

[SithRevan]

Those things you mentioned were only thought impossible to achieve with current technology, not theoretically impossible. The difference in traveling faster than light is that the theory of relativity clearly places a speed limit on particles with mass which means that accelerating past lightspeed is also theoretically impossible.

So in other words they though that those things I mentioned were also... theoretically impossible! Realistically I believe you can label something impossible or "Theoretically" impossible if you don't understand it's dynamics or complexities. I could, right now in fact, call modeling theoretically impossible because right now my thoughs are that I will never understand it. As you all know though that is not the case though. I just don't understand the dynamics and complexities involved in creating a sucessful model from scratch.

 

Really it's a matter of understanding and not understanding in my opinion.

[Achilles]

You're confusing the scientific term "theory" with the lay usage (which would most closely translate to "hypothetical"). To say something is theory is to say that we understand it extremely well. To say that FTL is theoretically impossible, means that is it impossible based on theories it invokes.

 

Take gravitation theory for instance. Using Newton's calculation we can plot the course of planets and stars and were able to put a man on the moon. But we have no idea what causes gravity. The good news is that we really don't need to in order to use it. That doesn't mean that gravity is something imagined, or that no one understands it, etc. We know the "what" just not the "why".

 

Our understanding of relativity is actually better than our understanding of gravity, and it says that FTL is impossible. As swfan28 points out above and as I have pointed out before, even if we were somehow able to attain the ability to accelerate to that kind of speed, any particle with mass will be increase until it reaches infinite mass at the speed of light.

[tk102]

You're confusing the scientific term "theory" with the lay usage

Ha ha, how many times have you to say that in threads over the past week?

 

Science really should make it easier for theories to be ratified into laws.

[Achilles]

If I had a dollar...

 

Seriously, they cover this stuff in grade school

[SithRevan]

You're confusing the scientific term "theory" with the lay usage (which would most closely translate to "hypothetical"). To say something is theory is to say that we understand it extremely well. To say that FTL is theoretically impossible, means that is it impossible based on theories it invokes.

 

Take gravitation theory for instance. Using Newton's calculation we can plot the course of planets and stars and were able to put a man on the moon. But we have no idea what causes gravity. The good news is that we really don't need to in order to use it. That doesn't mean that gravity is something imagined, or that no one understands it, etc. We know the "what" just not the "why".

 

Our understanding of relativity is actually better than our understanding of gravity, and it says that FTL is impossible. As swfan28 points out above and as I have pointed out before, even if we were somehow able to attain the ability to accelerate to that kind of speed, any particle with mass will be increase until it reaches infinite mass at the speed of light.

This is most likely true and I'm probabaly way off but I just don't see why everything has been put through a scientific microscope, analized, and if the thing we are analizing cannot be factualized it's claimed to be impossible.

 

Also, I have one question... you talk about realtivity... and other things that at the moment I don't understand as well as I should and you say through those laws of science we can without a doubt say that something like FTL is impossible. The question I have to ask though is... have we tried it yet? Faster then light travel? How can we sit here and say the it is unequivically impossible for us to obtain when we have not even tried to ever do something like it? Not to mention what is to say that the theory of relativity is not flawed or that one of the other theories preventing us from doing this flawed?

 

Realistically if you wanted to think about it sure we may know a lot about relativity in the terms that that said theory gives us but we do not know enough about space other then it's vastness to determin how well that theory would stand out there in who knows what kinds of different conditions. Relativity could be a whole new ball game if we actually new more about the dynamics of space, it could also be the same thing that we have been thinking it was all along.

 

I just think we kinda need to open our imaginations when it comes to space and space travel.

[Achilles]

This is most likely true and I'm probabaly way off but I just don't see why everything has been put through a scientific microscope, analized, and if the thing we are analizing cannot be factualized it's claimed to be impossible.

Heh...that's not how science works.

Scientists don't make any claim to anything they can't explain. It's not that FTL travel has been deemed impossible because there is insufficient evidence to draw a conclusion (as you seem to imply here), rather because they have mountain of verified evidence that rules out such a thing.

 

Also, I have one question... you talk about realtivity... and other things that at the moment I don't understand as well as I should and you say through those laws of science we can without a doubt say that something like FTL is impossible.

I certainly don't hold it against you for not understanding (I only have a layman's understanding of it myself). None of us were born with an inherent understanding of the theory of relativity. I guess where I get stuck is the part where you want refute it without understanding it first. Compounded by the fact that you seem to want to accuse scientists of doing this, when it is in fact you that is doing it, seems more than a little hypocritical

 

The question I have to ask though is... have we tried it yet? Faster then light travel? How can we sit here and say the it is unequivically impossible for us to obtain when we have not even tried to ever do something like it? Not to mention what is to say that the theory of relativity is not flawed or that one of the other theories preventing us from doing this flawed?

This speaks to a need for a deeper level of understanding of the scientific method, but I'll only address FTL and ToR.

 

In science, a theory is only as good as it's ability to make predictions and have those predictions confirmed with observations. So the theory of relativity made predictions such as the existence of dark matter, black holes, etc, all of which have been confirmed. This in conjunction with it's ability to explain certain things about our universe make it an incredibly powerful tool.

 

It also just so happens that this well-tested theory also shows that there is a speed limit in our universe. Nothing travels faster than light in a vacuum, therefore light is the fastest thing in our universe. Nothing goes faster. Gravity travels just as fast, as well as some other things I'm sure, but nothing travels faster. In fact, the mass of an object is proportionately increased at is reaches the speed of light. Therefore if a sub-atomic particle with a barely measurable mass were to get even 99.999% of the way there, it's mass would become such that it would start to swallow the universe (not good for us, btw). Coincidentally, as the object gained mass, it would also slow down

 

So have we tried it? No we haven't because first, we lack sufficient technology to get anything other that sub-atomic particles moving fast enough to approach those kinds of speed (interestingly the sub-atomic particles behave in accordance with ToR, telling us that Einstein's predictions were correct), and second, we already know that it won't work

 

That's the great thing about scientific discovery: Once you've eliminated all the things that something can't be, it conveniently limits the number of things something can be.

 

Realistically if you wanted to think about it sure we may know a lot about relativity in the terms that that said theory gives us but we do not know enough about space other then it's vastness to determin how well that theory would stand out there in who knows what kinds of different conditions.

I guess I would need to know what it is specifically that you think we lack sufficient understanding of in order to respond to this intelligently.

 

Relativity could be a whole new ball game if we actually new more about the dynamics of space, it could also be the same thing that we have been thinking it was all along.

Relativity may be refined, or even absorbed into a larger overarching theory, but it's far too late for it to be refuted.

 

I just think we kinda need to open our imaginations when it comes to space and space travel.

Absolutely. But we also have to reach out from what we know.

 

If you were to come home and find a dead person lying on your floor with a knife sticking out of their chest, you probably aren't going to waste a lot of time trying to rule out the jar of peanut butter in your pantry or the argyle socks in your drawer as murder suspects, are you?

[tk102]

Nothing travels faster than light in a vacuum, therefore light is the fastest thing in our universe. Nothing goes faster.

Should mention though, that theory relativity only precludes accelerating past the speed of light, but it does not prohibit the existence of particles that are already traveling faster than light (ie. tachyons.) The wiki link has a cool animation for how an approaching tachyon would appear to a stationary observer.

[Achilles]

Feel free to field the resulting questions re: the difference between acceleration and velocity. I was trying to keep it simple.

 

okay, whereas V = dx/dt, A = dV/dt = d²x/dt² ~tk

[SithRevan]

@Achilles: Well then I guess I have lots to learn then, I just get a little bit argumentitive over that subject when somebody tries to disprove it. I love the prospect of one of these days being able to get out into space and travel at FTL speeds.

 

I do however don't think it's impossible, that is my personal opinion and it'll probably never chage until I see something going very close to the speed of light but not being able, physically, to break it and even then I'll probably tell myself that our technology is not yet advanced enough for us to do it.

Should mention though, that theory relativity only precludes accelerating past the speed of light, but it does not prohibit the existence of particles that are already traveling faster than light (ie. tachyons.) The wiki link has a cool animation for how an approaching tachyon would appear to a stationary observer.

Woah, I didn't think that a Tachyon particle Actually existed. I thought it was just somthing out of Star Trek.

[Achilles]

Woah, I didn't think that a Tachyon particle Actually existed. I thought it was just somthing out of Star Trek.

Still largely hypothetical so...

[SithRevan]

Still largely hypothetical so...

If the Tachyon particle, lets say was proven to be fact tommorrow, could we use that in traveling speeds FTL? Or would that also be a no go?

[Achilles]

That would depend on what we learned about it when it was verified. Based on my understanding of what we've been able to hypothesize thus far about tachyons is that they can never slow down enough to approach the speed of light. Therefore, on this side of the speed limit, there are barriers to prevent that point being reached and on the opposite side there are similar (but opposite barriers).

 

So in the observable universe: a particle with mass will increase in mass as it accelerates, thereby slowing it down.

 

In the hypothetical tachyon...realm: a particle with with energy will lose energy as it slows down, thereby causing it to speed up (least that's how I read it).

 

If tachyons are real, it would seem that the speed of light is an impenetrable barrier from either side. If they aren't real, then ToR already tells us what will happen.

[tk102]

So in the observable universe: a particle with mass will increase in mass as it accelerates, thereby slowing it down.

 

In the hypothetical tachyon...realm: a particle with with energy will lose energy as it slows down, thereby causing it to speed up (least that's how I read it).

It helps me when I see the equation:

 

This says, if v<c (subluminal speeds), then as v increases and approaches c, the denominator becomes smaller, meaning that E becomes larger. This means the energy of the particle becomes larger and larger as the particle increases in velocity. Note when v=0, we get E=mc2.

 

Now if v>c (superluminal speeds) then we have an imaginary denominator. Because E is real, m must be imaginary also. Factoring out the imaginary number i and defining z as m/i you get:

This says as v decreases and approaches c, the denominator gets smaller and E becomes larger. But as v increases and becomes much larger than c, the denominator get larger and E decreases. So as a tachynon slows down, it gains energy, but as it speeds up it loses energy. Weird.

 

Just as weird is the implication that its mass is imaginary.