Is faster than light travel possible?

[Philippe Lemay]

Simple question, give your thoughts and opinions on the matter.

[DrWho]

No.

[Jens]

Ditto.

[Philippe Lemay]

lol, I don't necessarily mean just right this minute. The poll allows the option to take into consideration thousands of years of technological and cultural advancement. You think that if we are still alive by the year 6000, we still won't have figured out a way to do it?

[Jens]

No, I mean that it's impossible now, impossible in 1,000 years, impossible for as long as you want.

[DrWho]

lol, I don't necessarily mean just right this minute. The poll allows the option to take into consideration thousands of years of technological and cultural advancement. You think that if we are still alive by the year 6000, we still won't have figured out a way to do it?

Yes.

[Philippe Lemay]

Alright, I respect your opinions. That's why I added those options in the poll.
(Would have been nice if those opinions had been a bit more involved... but what can one do.)

I'm of the opinion that it is possible, but would involve an extreme level of engineering beyond what is imaginable currently. We know that some types of black-holes can bend space in such a way that it is spinning faster than the speed of light. But yea, taming the forces involved in black-holes would be no easy task.

The concept is pretty cool, it's known as frame-dragging, mentioned in this wiki article here. http://en.wikipedia.org/wiki/Ergosphere
Probably the only known example of space being bent at FTL speeds in nature. But at last we know it did happen! We just have yet to control it.

[DrWho]

How does frame dragging allow you to travel faster than light?

[Philippe Lemay]

I'll admit I am not at all an expert on the details, but it's this line here that perticularly caught my eye.

Within the ergosphere, spacetime is dragged along in the direction of the rotation of the black hole at a speed greater than the speed of light in relation to the rest of the universe.

It's not exactly FTL travel, but it does at least show that bending space in a way that the volume in that space is indeed moving faster than light is possible! We just need a crazy giant spinning black-hole to do it. lol

[DrWho]

It's not exactly FTL travel, but it does at least show that bending space in a way that the volume in that space is indeed moving faster than light is possible! We just need a crazy giant spinning black-hole to do it. lol

You don't need a black hole for this, as spacetime expansion at FTL speeds also occurs at large cosmological scales. But that does not mean that matter is traveling at FTL speeds.

[slang]

No, I mean that it's impossible now, impossible in 1,000 years, impossible for as long as you want.

Ditto.

Search this subforum for FTL and you'll find many, many threads on this topic. Add "causality" to the search and you'll probably find a few good threads.

[Philippe Lemay]

Right but the expansion of the universe is so wide-spread that it's not as easy for us to directly appreciate it. The rotating black-hole does allow a much more apparent motion for a volume of space at superluminal speeds.

I'll admit it's not matter moving (in the conventional sense) at faster than light speeds, because that is of course impossible. But you can't deny that the volume of space is being dragged at FTL speeds. And that in that sense, the volume is "traveling" faster than the speed of light. Even if it's just doing circles round and round.

Search this subforum for FTL and you'll find many, many threads on this topic. Add "causality" to the search and you'll probably find a few good threads.

I suspected there had been other threads discussing it, but I wanted to make a poll to see the over-all status of the community on the matter. I can see it's generally pessimistic... I was expecting to see at least a few Number 2s.

[astromark]

I am one of those people that can conceptualize the actual size of the universe.
I also have the capacity to comprehend just how fast light does travel.
When I voted NO. It was a well considered choice.
We have learned that matter as we know it would require more energy than is available to propel it to light speed. Its not possible.

[DrWho]

The rotating black-hole does allow a much more apparent motion for a volume of space at superluminal speeds.

How is it more apparent?

But you can't deny that the volume of space is being dragged at FTL speeds.

I don't believe that I ever denied that.

And that in that sense, the volume is "traveling" faster than the speed of light.

Space is space.

I was expecting to see at least a few Number 2s.

Lol, do you want to rephrase that!

[Philippe Lemay]

We have learned that matter as we know it would require more energy than is available to propel it to light speed. Its not possible.

I know, I know all that. (You can tone down the condescension a tad.) I know that as an object approaches the speed of light it's mass increases to infinity. I know that due to time dilation the apparent speed of light, even to a traveler moving at 99.9% C will always seem just as distant and un-attainable. I know. I'm not suggesting we use conventional travel here. I'm thinking more along the lines of black-hole masses and wormhole style distortions of space.

Oh wait, that's a good one. What do you band of super-brains think about wormholes? What's the problem there? I know it would require something like the mass of several suns, but just because it would be hard to achieve and take billions of years to complete doesn't make it completely impossible.

How is it more apparent?

I think the acceleration of the universe happens over billions of lightyears. The event horizon is more like... kilometers across I think. Easier to place the difference between space that is not moving and space that is moving, to get a better sense that there is some travel going on.

[slang]

Lol, do you want to rephrase that!

[Philippe Lemay]

Space is space.

I'm assuming you know more about black-holes than I do so I will address this question in hopes that you can clarify the issue for me.

We assume a black-hole that has an event horizon 500 meters across. The Ergo-sphere is wider than this, but by how much exactly isn't important. We assume a particle is trapped in this ergosphere, an... electron lets say. If the ergosphere is spinning in such a way that it can frame-drag the electron so that the space in which the electron is sitting in is moved to the opposing side of the blackhole (with respects to the rest of the universe) and does so faster than 0.0000016 seconds.

In this circumstance, can we not say that the electron has traveled a roughly 500 meter distance faster than if a beam of light had attempted it?

[DrWho]

Oh wait, that's a good one. What do you band of super-brains think about wormholes? What's the problem there?

One problem would be that they have never been detected and probably do not exist.

I know it would require something like the mass of several suns, but just because it would be hard to achieve and take billions of years to complete doesn't make it completely impossible.

Well, you'd need something even more exotic than a number of suns. Most theoretical models are pretty speculative at best, with quite a bit of handwaving in the analysis.

[Jens]

Oh wait, that's a good one. What do you band of super-brains think about wormholes?

Who said anything about super-brains? I don't claim to know any better than you. You just asked for opinions and I offered mine. We might disagree on this, but I'm not sure why that warrants that label.

I sort of agree with DrWho that there may not even be wormholes, but there are people on both sides of this issue. I don't think you need to be discouraged just because the first two people who who showed up happened to disagree.

[Philippe Lemay]

Who said anything about super-brains? I don't claim to know any better than you. You just asked for opinions and I offered mine. We might disagree on this, but I'm not sure why that warrants that label.

The bluntness in which you guys replied kind of gave that impression. Kind of like, "Of course not! We know this subject through and through. How dare you even pose such a ridiculous question!?"

Even in other real-science forums the discussion was never so... one-minded. Maybe this wasn't the best place to bring up this question.
And it's not just the first 2 people, looks more like it's the first 5 people. And I suspect the rest of the community will be of like mind. It's OK, this place is just much more firmly grounded in Real-World science.

[Jens]

The bluntness in which you guys replied kind of gave that impression. Kind of like, "Of course not! We know this subject through and through. How dare you even pose such a ridiculous question!?"

I'm sorry if I gave that impression. I can see how it might. It was just that DrWho answered so succintly and I was trying to be cute by answering the same way. I didn't mean to say it was a ridiculous question, though. Clearly it's something that interests me, otherwise I wouldn't have bothered to read.

[Philippe Lemay]

OK, this is actually a good thing. I had this guy on another thread who is a self proclaimed savant, and not only does he believe FTL will one day be possible, he thinks that he could unlock it in 10 years if he really wanted to (I mentioned it in another thread here a while back).

So yea, if I can't convince you guys in the possibility of FTL, I can at least collect a few good reasons as to how it would be exceedingly hard (and then rub them in this other guy's face). Plus it would help me to understand the issue better, recognizing the obstacles is the first step in overcoming them.

Now, about bending space, there's something that's always bothered me.
Suppose we have a spacecraft at Sol all ready for it's fantastic voyage across interstellar space. It's destination is Sirius let's say, located 8.6 lightyears away.

So the spacecraft uses some unspecified mechanism, synthetic gravity, exotic particles, or magical rainbows, point is that it creates a gravitational force that bends space in the direction of the Sirius system. The spacecraft rides that ripple in spacetime like a surfer on wave, and all's good so far.

But what happens when the "wave" arrives at Sirius? From the perspective of the rest of the universe, there could be just a few kilometers separating our spacecraft from the target system. But from the spacecraft's point of view there's still lightyears of distance separating them. It can't just "hop" the gap, because there's still an impossibly large space that lies before it.

And once the space is un-distorted, the ship would just come back where it started... does this mean that bending space could be a dead-end in possible ways to go FTL?

[DrWho]

It was just that DrWho answered so succintly and I was trying to be cute by answering the same way.

So, it's my fault? Philippe, you asked a simple question, I gave a simple answer.

It's OK, this place is just much more firmly grounded in Real-World science.

Well, this is a forum about mainstream Q&A after all.

[mugaliens]

Given the poll statistics, Phillipe, particularly given the nature of those who frequent this board, I'm curious as to what's on your mind at the moment? Are you considering the responses and the background behind them?

[swampyankee]

Given what we know now (weasel words ;-)), no.

[Jeff Root]

It took many years of gradually adding to my knowledge of the Universe to
come to the opinion that faster-than-light travel and time travel are almost
certainly impossble. I say "almost certainly" here, where I can explain
myself. In the poll I just selected "not possible". My opinion is that there
is no apparent good evidence that FTL is possible, and if such evidence
existed it ought to have become apparent to us by now. Of course, just
twelve years ago there was no apparent good evidence for the accelerated
expansion of the Universe, which there was a year later. That discovery
was not predicted, which may be more annoying to me than to anyone else
in the whole world because I had at that time already been thinking about a
mechanism which could cause such an acceleration. I just hadn't thought
about it deeply enough to realize that my imagined mechanism could cause
the expansion to accelerate.

So I think it is possible that FTL is possible, but very, very unlikely. Far
more likely that it is impossible.

If you come to the same opinion that I have come to, there is no apparent
reason for you to come to it any more rapidly than I did. And there is a
wide range of possible values of "possible" to choose from.

-- Jeff, in Minneapolis

[DrWho]

Of course, just twelve years ago there was no apparent good evidence for the accelerated expansion of the Universe, which there was a year later. That discovery was not predicted, which may be more annoying to me than to anyone else in the whole world because I had at that time already been thinking about a mechanism which could cause such an acceleration. I just hadn't thought about it deeply enough to realize that my imagined mechanism could cause the expansion to accelerate.

There's a big difference between the two notions. There are good physical reasons why FTL isn't possible, but no such constraints on accelerated expansion. It's equally possible that the universe might be decelerating, expanding at a constant rate or at an accelerated rate. It's just a matter of observation.

[NorthernBoy]

It's OK, this place is just much more firmly grounded in Real-World science.

It tends to be filled with people who've actually worked n science, I think.

If I were a betting man, which I am, I'd bet on it not being achieved while humanity is still around to see it.

Well, actually I wouldn't, as that's a bet that I'd not be around to collect on, but hopefully you see what I mean...

[Ken G]

One must take the meaning that FTL means "getting from event A to event B faster than light in a vacuum could get from event A to event B." I can always choose a coordinate system where I'm moving faster than c, it means no more than the spinning black hole example.

[SuperKevin]

Mathmatically it's not possible to exceed the speed of light. This doesn't mean however we can't get around from one place to another using other methods. If we/anyone don't find a way to travel much quicker there could be billions of intelligent lifeforms that would never actually meet eachother.