Is it possible to go faster than light?

How does science work? And what's all this about quantum mechanics?

Moderators: AMod, iMod

User avatar
Noax
Posts: 670
Joined: Wed Aug 10, 2016 3:25 am

Re: Is it possible to go faster than light?

Post by Noax » Mon Nov 14, 2016 2:03 pm

Greta wrote:Then again, when we view those galaxies travelling away from us at that speed, we are probably viewing light from long dead galaxies, in which case we are actually looking into the past :)
Quite the opposite. In a relativistic framework (our inertial frame for instance), we see distant galaxies which are very young, and since they move so fast, time dilation is significant. Those galaxies are still far younger than ours even now. Under this framework, nothing moves faster than light.

Only in the frame of distant galaxy X is the galaxy now long dead, since we're the young one with the dilated time.

Under the comoving framework, that distant galaxy is about the same age now as our own (as are all galaxies since they're all reasonably stationary). In that framework, distant galaxies might be increasing their separation from us at a rate of 20 C, but in comoving framework, there is no maximum to that speed. There is still a speed of light, meaning light from those sufficiently distant places cannot ever reach us.

The difference between the velocity of galaxy X in one framework or the other has to do with a different definition of where that galaxy is now, which is an arbitrary selection. In one second of earth time, how much time passes for galaxy X? You get very different answers, and thus very different velocities, depending ones choice of the foliation of space (folation means how one chooses to order events in spacetime).

User avatar
Terrapin Station
Posts: 1488
Joined: Wed Aug 03, 2016 7:18 pm
Location: NYC Man

Re: Is it possible to go faster than light?

Post by Terrapin Station » Mon Nov 14, 2016 2:59 pm

Philosophy Explorer wrote:
surreptitious57 wrote:
Philosophy Explorer wrote:
Infinite mass has nothing to do with this
Why cannot objects travel faster than light speed
A wormhole can shorten the distance between two points. Let's take a specific example. Take two points that are separated 18.6 million miles in space. This means it takes light 100 seconds to travel from point to the other.

Let's say a wormhole has shortened the distance to just 1 mile between the points. Then a spaceship can travel the distance in less than a second which is faster than light doing it in 100 seconds.

Clearly the spaceship is moving at less than the speed of light so infinite mass doesn't enter the picture, BUT in a manner of speaking, it has moved faster between the two points than light has due to the reduced distance involved.

Wormholes are theoretical and remain to be discovered. I have faith in Einstein.

PhilX
You're answering your own question here: "Clearly the spaceship is moving at less than the speed of light."

There's no manner of speaking in which it moved faster than light. You could say, "The spaceship, using the shortcut available, which decreased the spatial distance necessary to travel, traveled from point A to point B more quickly than light can when light takes this alternate spatial path." That's not traveling faster than light. It's simply taking a different route.

Re wormholes, no one is ever going to discover them, because they hinge on a notion of space that's incorrect. (Namely, the idea that space is something like a "substance to be traveled in.")

Whether light really has a speed limit, and whether anything can travel faster than it is another issue. Our current physics says that there is a speed limit and nothing can travel faster than light. But our current physics could be sorely mistaken about what the world is really like, and in some cases, it certainly is mistaken (for example, in treating space as anything like a "substance to be traveled in").

User avatar
Greta
Posts: 4389
Joined: Sat Aug 08, 2015 8:10 am

Re: Is it possible to go faster than light?

Post by Greta » Mon Nov 14, 2016 10:45 pm

Noax wrote:
Greta wrote:Then again, when we view those galaxies travelling away from us at that speed, we are probably viewing light from long dead galaxies, in which case we are actually looking into the past :)
Quite the opposite. In a relativistic framework (our inertial frame for instance), we see distant galaxies which are very young, and since they move so fast, time dilation is significant. Those galaxies are still far younger than ours even now. Under this framework, nothing moves faster than light.
I added the smiley to say I wasn't making a serious point but playing with irony.

What we see of a distant galaxy in Hubble's deep field image is, as you noted, a very young galaxy in an infant universe. However, that galaxy may well have collided with another galaxy in the interim and not be recognisably existent today.
Noax wrote:Under the comoving framework, that distant galaxy is about the same age now as our own (as are all galaxies since they're all reasonably stationary). In that framework, distant galaxies might be increasing their separation from us at a rate of 20 C, but in comoving framework, there is no maximum to that speed. There is still a speed of light, meaning light from those sufficiently distant places cannot ever reach us.
Then again, maybe space has a speed limit too?

Also, I'm wondering why it's assumed that dark energy will continue speeding up forever, given that it's slowed once before in the past. To me, the idea of "speeding up forever" is not something I would associate with the usual way nature works. Then again, our models are rendered incongruous by the big bang too.

Philosophy Explorer
Posts: 5621
Joined: Sun Aug 31, 2014 7:39 am

Re: Is it possible to go faster than light?

Post by Philosophy Explorer » Mon Nov 14, 2016 10:52 pm

Greta wrote:
Noax wrote:
Greta wrote:Then again, when we view those galaxies travelling away from us at that speed, we are probably viewing light from long dead galaxies, in which case we are actually looking into the past :)
Quite the opposite. In a relativistic framework (our inertial frame for instance), we see distant galaxies which are very young, and since they move so fast, time dilation is significant. Those galaxies are still far younger than ours even now. Under this framework, nothing moves faster than light.
I added the smiley to say I wasn't making a serious point but playing with irony.

What we see of a distant galaxy in Hubble's deep field image is, as you noted, a very young galaxy in an infant universe. However, that galaxy may well have collided with another galaxy in the interim and not be recognisably existent today.
Noax wrote:Under the comoving framework, that distant galaxy is about the same age now as our own (as are all galaxies since they're all reasonably stationary). In that framework, distant galaxies might be increasing their separation from us at a rate of 20 C, but in comoving framework, there is no maximum to that speed. There is still a speed of light, meaning light from those sufficiently distant places cannot ever reach us.
Then again, maybe space has a speed limit too?

Also, I'm wondering why it's assumed that dark energy will continue speeding up forever, given that it's slowed once before in the past. To me, the idea of "speeding up forever" is not something I would associate with the usual way nature works. Then again, our models are rendered incongruous by the big bang too.
The existence of dark energy has recently been called into question.

PhilX

PS I should explain this is based on a new catalog of the stars.

User avatar
Noax
Posts: 670
Joined: Wed Aug 10, 2016 3:25 am

Re: Is it possible to go faster than light?

Post by Noax » Mon Nov 14, 2016 11:44 pm

Greta wrote:I added the smiley to say I wasn't making a serious point but playing with irony.
Smiley accepted.
What we see of a distant galaxy in Hubble's deep field image is, as you noted, a very young galaxy in an infant universe. However, that galaxy may well have collided with another galaxy in the interim and not be recognisably existent today.
True, we don't know the fate of the thing from what we see. But when is it's today? Definition of that completely defines its distance and rate of change of said distance, and if that rate of change is more than C.
Then again, maybe space has a speed limit too?
Space is a thing that moves?

User avatar
Hobbes' Choice
Posts: 8364
Joined: Fri Oct 25, 2013 11:45 am

Re: Is it possible to go faster than light?

Post by Hobbes' Choice » Tue Nov 15, 2016 12:16 am

Philosophy Explorer wrote:My position is it is possible. Google wormhole and read what Einstein and Posen have theorized.

Einstein has been right so often (his latest triumph, gravitational waves, has been proven about a year ago). It remains for someone to discover wormholes.

PhilX
A human cannot stay a human in a wormwhole, even if there are such things.

So no you cannot travel faster than light.

User avatar
Greta
Posts: 4389
Joined: Sat Aug 08, 2015 8:10 am

Re: Is it possible to go faster than light?

Post by Greta » Tue Nov 15, 2016 12:17 am

Noax wrote:
Then again, maybe space has a speed limit too?
Space is a thing that moves?
I suppose you could say that space "moves" in that it is not static. The purported expansion occurs at certain rates and that relates to the speed that galaxies are apparently moving apart.

User avatar
Greta
Posts: 4389
Joined: Sat Aug 08, 2015 8:10 am

Re: Is it possible to go faster than light?

Post by Greta » Tue Nov 15, 2016 12:29 am

Philosophy Explorer wrote:The existence of dark energy has recently been called into question.

PS I should explain this is based on a new catalog of the stars.
I've heard some vague rumblings about this. Also, dark matter is also being called into question. I feel that MOND at galactic scales needs to remain on the table because we already have an example of gravity's behaviour being scale-dependent (quantum).

There may be other explanations for the increasingly pronounced redshift, perhaps pertaining to unknown qualities of such vast amounts of space. We know that space is not entirely empty so maybe space has some infinitesimal level of translucence that only becomes noticeable at extremely large scales? Maybe light cannot travel forever in space just as sound cannot travel forever in an atmosphere, with the waves gradually degrading?

Philosophy Explorer
Posts: 5621
Joined: Sun Aug 31, 2014 7:39 am

Re: Is it possible to go faster than light?

Post by Philosophy Explorer » Tue Nov 15, 2016 12:54 am

Hobbes' Choice wrote:
Philosophy Explorer wrote:My position is it is possible. Google wormhole and read what Einstein and Posen have theorized.

Einstein has been right so often (his latest triumph, gravitational waves, has been proven about a year ago). It remains for someone to discover wormholes.

PhilX
A human cannot stay a human in a wormwhole, even if there are such things.

So no you cannot travel faster than light.
What do you expect to happen with a human in a wormhole (depending on what type of wormhole?)

PhilX

User avatar
Greta
Posts: 4389
Joined: Sat Aug 08, 2015 8:10 am

Re: Is it possible to go faster than light?

Post by Greta » Tue Nov 15, 2016 1:09 am

Philosophy Explorer wrote:
Hobbes' Choice wrote:
Philosophy Explorer wrote:My position is it is possible. Google wormhole and read what Einstein and Posen have theorized.

Einstein has been right so often (his latest triumph, gravitational waves, has been proven about a year ago). It remains for someone to discover wormholes.
A human cannot stay a human in a wormwhole, even if there are such things.

So no you cannot travel faster than light.
What do you expect to happen with a human in a wormhole (depending on what type of wormhole?)
I heard that the math apparently suggests that anything that approaches a wormhole would be first incinerated and then crushed.

Philosophy Explorer
Posts: 5621
Joined: Sun Aug 31, 2014 7:39 am

Re: Is it possible to go faster than light?

Post by Philosophy Explorer » Tue Nov 15, 2016 1:12 am

Greta wrote:
Philosophy Explorer wrote:
Hobbes' Choice wrote:
A human cannot stay a human in a wormwhole, even if there are such things.

So no you cannot travel faster than light.
What do you expect to happen with a human in a wormhole (depending on what type of wormhole?)
I heard that the math apparently suggests that anything that approaches a wormhole would be first incinerated and then crushed.
Is that all?

PhilX

User avatar
Greta
Posts: 4389
Joined: Sat Aug 08, 2015 8:10 am

Re: Is it possible to go faster than light?

Post by Greta » Tue Nov 15, 2016 1:20 am

Philosophy Explorer wrote:
Greta wrote:
Philosophy Explorer wrote:
What do you expect to happen with a human in a wormhole (depending on what type of wormhole?)
I heard that the math apparently suggests that anything that approaches a wormhole would be first incinerated and then crushed.
Is that all?
Probably not. Still, when you're speaking about the kinds of temperatures that are closer to that of the big bang than any we are familiar with, it rather renders all other consequences moot for the practically-minded :)

surreptitious57
Posts: 4028
Joined: Fri Oct 25, 2013 6:09 am

Re: Is it possible to go faster than light?

Post by surreptitious57 » Tue Nov 15, 2016 3:51 am

Greta wrote:
Philosophy Explorer wrote:
What do you expect to happen with a human in a wormhole ( depending on what type of wormhole )
I heard that the math apparently suggests that anything that approaches a wormhole would be first incinerated and then crushed
This is similar to what would happen with a black hole except that the incineration and crushing would happen inside it beyond the event horizon

Philosophy Explorer
Posts: 5621
Joined: Sun Aug 31, 2014 7:39 am

Re: Is it possible to go faster than light?

Post by Philosophy Explorer » Tue Nov 15, 2016 7:58 am

Greta wrote:
Philosophy Explorer wrote:The existence of dark energy has recently been called into question.

PS I should explain this is based on a new catalog of the stars.
I've heard some vague rumblings about this. Also, dark matter is also being called into question. I feel that MOND at galactic scales needs to remain on the table because we already have an example of gravity's behaviour being scale-dependent (quantum).

There may be other explanations for the increasingly pronounced redshift, perhaps pertaining to unknown qualities of such vast amounts of space. We know that space is not entirely empty so maybe space has some infinitesimal level of translucence that only becomes noticeable at extremely large scales? Maybe light cannot travel forever in space just as sound cannot travel forever in an atmosphere, with the waves gradually degrading?
This just came out yesterday and may help to clarify. This includes a video:

http://www.sciencealert.com/watch-why-s ... isappeared

PhilX

surreptitious57
Posts: 4028
Joined: Fri Oct 25, 2013 6:09 am

Re: Is it possible to go faster than light?

Post by surreptitious57 » Tue Nov 15, 2016 9:34 am

Greta wrote:
Maybe light cannot travel forever in space just as sound cannot travel forever in an atmosphere
Photons in vacuum travel at one speed as they have zero rest mass and in space that is forever

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests