Ways To Travel Faster Than Light Without Violating Relativity

StartsWithABang writes: It's one of the cardinal laws of physics and the underlying principle of Einstein's relativity itself: the fact that there's a universal speed limit to the motion of anything through space and time, the speed of light, or c. Light itself will always move at this speed (as well as certain other phenomena, like the force of gravity), while anything with mass — like all known particles of matter and antimatter — will always move slower than that. But if you want something to travel faster-than-light, you aren't, as you might think, relegated to the realm of science fiction. There are real, physical phenomena that do exactly this, and yet are perfectly consistent with relativity.

Comments

faster than light never violates Relativity

[catmistake]

Nothing can go as fast as light. Slower or faster, sure, but not c.

Re:faster than light never violates Relativity

[catmistake]

Relativity requires that nothing can move through space faster than light.

Relativity requres that nothing can move through space as fast as light (c). Nothing with mass moving slower than c can reach c by moving faster, due to increase in mass and infinite energy required to reach c, and nothing moving faster than light can slow down to c, for the same reasons. The quote from teh article is at best misleading and at worst, false.

Re:faster than light never violates Relativity

[circletimessquare]

we have no technology remotely capable of this, but:

1. a quantum entangled version of yourself moves away from you (at "normal" speed, less than c)

2. say... many light years away (i know, i said we have no technology remotely capable of this, bear with me here, just a thought experiment)

3. the "copy" of you can't violate c, but at the last moment, one version of you interacts with its surroundings, collapsing you to that single copy. such that you have achieved instantaneous transportation across light years of distances

doesn't that happen faster than c?

Re:faster than light never violates Relativity

[catmistake]

You're at a very straight, very long beach. Imagine parallel waves striking the shore at a vanishingly slight angle. The point that the wave meets the shore moves along as the intersection of wave and beach occurs. As the waves get closer and closer to parallel with the beach, but not quite parallel, eventually that intersection point will be moving much faster than c.

But the interesection point between waves and shore doesn't have mass, isn't really a "thing" that's moving.

Re:faster than light never violates Relativity

[circletimessquare]

that's an excellent analogy, thank you

and you are correct, there's no real movement, only a collapse to a single frame of reference

however, for the intents and purposes of outside human observers, haven't you instantly blinked across light years?

Re:faster than light never violates Relativity

[Maritz]

You can only transmit random information with this method. You can 'instantly' know the state of the entangled partner, many light years away, but their spin will be 50% one way and 50% the other. So yes you can transmit random noise faster than light. ;)

Re:faster than light never violates Relativity

[Anonymous Coward]

Away with your sophistry! Your angles, and parallels and intersections! When will you geeks come into the 21st century and present your ideas as sensible powerpoint presentations!

-- Yours, Management.

Re:faster than light never violates Relativity

[bobbied]

I want the last 5 minutes back please.

Not until you violate the cosmic speed limit and go back in time..

Re:faster than light never violates Relativity

[Immerman]

Actually, correlated random noise is extremely useful for cryptography. At its simplest, Alice takes their noise as received, Bob takes the inverse of their received noise, and since the noise source is entangled they are then guaranteed to have the same noise, which can be used as an encryption key, or even a one-time pad.

Re:faster than light never violates Relativity

[fahrbot-bot]

You're at a very straight, very long beach.

But, I'm in a maze of twisty little passages, all alike so I think I'm screwed.

Re:faster than light never violates Relativity

[Pikoro]

I realize that this is a very simplistic explanation, but think of quantum entanglement like this:

You have 2 cubes. Each cube can be only either blue or green. You have no idea what color each cube is as you packed them into boxes for mailing across the galaxy in a completely dark room. They are then mailed.

Now, you open your box. Turns out that your cube is green. You instantly know that the other cube is blue, even if it's on the other side of the galaxy, however, you have no way of communicating your discovery to the other party.

You now have instant knowledge of what color the remote cube is, but no information has been transferred.

Simple enough?

Re:faster than light never violates Relativity

[schlachter]

must I do it with a pair if scissors, or can I just use one?

Re:faster than light never violates Relativity

[circletimessquare]

i get it

so "he went to alpha centauri"/ "he didn't leave at all" isn't known until you interact

there's no guaranteeing you go anywhere

schrodinger's rocket ship

Re:faster than light never violates Relativity

[Anonymous Coward]

No. That's not quite how quantum entanglement works.

It's a bit more like a pair of boxes that contain the same book. If you open both of them at once, you're not blinking the book across instantly. The book exists in both locations at once, but cannot be seen until the box is opened.

As far as we are aware, quantum entanglement is like a pair of dice that are guaranteed to have the same result after you roll them once. We don't actually know for sure if the roll is random, because cannot break the mechanics of the dice into separate components (which is why the mechanics are "quantum").

Re:faster than light never violates Relativity

[Mal-2]

Even simpler, you point a laser pointer at the sky, and sweep it manually over a very distant target (bigger than the moon, but further away as well). Clearly your hand is not going to move faster than light, but the point where the beam finally hits something very well might. Again, this intersection is not a "thing", and cannot be used to communicate faster than the speed of light.

Medium.com Alert!

[weilawei]

Danger Will Robinson, Danger! This article doesn't actually provide what its title claims. Clickbait, pure and unadulterated. Plus, it's not even that informative. All stuff we see in Slashdot comments any time anyone mentions FTL travel.

Re:Medium.com Alert!

[sectokia]

Terrible click bait, doesn't mention a single way to go faster than light. Most nerds would already know all of this.

Re:Medium.com Alert!

[DigiShaman]

Well, in that case, this article proves that least bullshit can be accessed at the speed of light.

Re:Medium.com Alert!

[Skarjak]

Since when do we get all these medium.com articles? Nowadays I just skip the story when I see it's from their website. Did an editor cofound it or something?

Light speed

[ArcadeMan]

The fact that there's a universal speed limit to the motion of anything through space and time, the speed of light, or c. Light itself will always move at this speed.

Except, you know, cases where we slowed down light itself. By a lot.

TL;DR

[Lord Duran]

You can go faster than light goes in certain materials because then it travels slower than c. If you do that, badass things happen.

That said, the article is pretty well written IMHO, so if you've never heard of this before, go ahead and read it.

Article's summary

[m.alessandrini]

Light goes slower than c in any medium different from vacuum. Some objects can go faster than light in that medium (but not faster than c of course).

Re:Article's summary

[Anonymous Coward]

And even then, light in a vacuum goes slower than the actual speed of light.

The truest speed of light can't be attained in nature due to the fact that the vacuum is not, in fact, a true vacuum. There are virtual particles popping in and out of existence constantly, which light interacts with.
Creating 2 casimir plates to create a true vacuum would give you the true speed. What that speed may be is not known since, as far as I know, nobody has made such an experiment. But it is theorized to not be that big of a change.

Nobody knows what effect the quantum vacuum has on EM radiation for sure.
Hell, for all we know, it could be stealing energy off said photons, making a larger universe considerably smaller, and surely breaking some "laws" while we are at it, but since we are all about breaking the laws of physics recently, everything is up for grabs, all laws must go before 6pm!
It is already a possible culprit for the expansion of the universe, next to dark energy.
And given that weird ass EM Drive, that seemingly is able to bounce energy OFF of "space itself" (the vacuum), it appears that it is possible to directly interact with it, and it also gives even more momentum to Hawking Radiation being capable of stealing mass from blackholes.
The distinction between virtual and ordinary particles just got weirder, if it holds that is. (I believe NASA is preparing a further test for next month, sometime this summer at least, to figure out what the hell that thing is doing)

Science is going to be a very interesting topic over the rest of this century.
Get in while you can kids. What's that, we're all old? Oh yeah. Sorta screwed that one up.

Don't bother reading

[gsslay]

The whole thing hinges on the phrase in the first paragraph; "depending on what you mean by a "thing", "faster-than-light", and "travel""

If you want to play around with semantics and definitions, then you've got an article. Otherwise, nothing new here. Speed of light unchallenged.

Re:Don't bother reading

[sootman]

In that case, I've banged a lot of chicks, depending on what you mean by "banged", "a lot", and "chicks".

Poorly written

[prisoner-of-enigma]

Poorly written article and misleading summary. Basically the article says you can "travel faster than the speed of light" without violating relativity...but neglects to mention which "speed of light" you're beating. Light speed is different in depending upon what medium -- or lack thereof -- it's traveling through. It's possible to slow light down to the point where you can walk faster than that speed of light. But you're not violating relativity by doing so because you're moving through a different medium.

So, hyperdrives...not so much.

Light speed also depends on time

[ArcadeMan]

And time itself is also quite complex. Here's a quote from someone who explains time:

"People assume that time is a strict progression of cause to effect, but *actually* from a non-linear, non-subjective viewpoint - it's more like a big ball of wibbly wobbly... time-y wimey... stuff." - The Doctor.

Really Though, DO NOT Bother Reading

[Anonymous Coward]

The whole thing hinges on the phrase in the first paragraph; "depending on what you mean by a "thing", "faster-than-light", and "travel""

If you want to play around with semantics and definitions, then you've got an article. Otherwise, nothing new here. Speed of light unchallenged.

Yeah ... came here, read the article, want my money back.

What a complete waste of time this article was!

Did you know that if you try to send a photon through a solid wooden door, it won't ever make it ... however if you shout at the door, the sounds will be heard softly on the other side? In this case of "breaking the light speed barrier" our calculations show that not only are your vocal sound waves traveling faster than the speed of light but since light never got through the door and time still marches on, you are approaching a speed infinitely faster than the speed of light!

Mind blown? Or are you just angry that I got you to read that horseshit?

Your listening to slashdot fm

[Anonymous Coward]

"All Ethan, all the time. Now lets go to Ethan for the forecast"

"Thank you Ethan, today will be mostly medium.com with some light links to other sites"

"Well that's the weather, now over to Ethan for the business"

"Well Ethan, Dice Holding have announced a shocking drop in profits after letting once popular Slashdot.com devolve into a medium.com link aggregator. Sharholders are angry, but DHI spokesperson Ethan Siegel insists the firm is making all the right moves, and it's purely market forces outside there control that have lead to this huge decline in readership. Now back to you Ethan"

"We will have more on that, and other stories on the hour, but now Ethan Turner Overdrive, and 'you ain't seen nothing yet'"

C is not what people think it means

[goombah99]

It's very easy to travel 100 light years in less than 100 years. Thus for all intents and purposes, one can travel distances at faster than the speed of light. The theory of relativity does not prevent this. You can without violating any laws accelerate a rocket ship at a comfortable 1g for as long as your fuel holds out. You will not get more massive. It will not take increasing amounts of fuel to maintain the 1g acceleration. If you accelerate for 1 year at 1g then you will know that you covering the distance to your destination at faster than the speed of light.

What is true about relativity is this: and OUTSIDE observer will see you traveling at less than the speed of light. But from your perspective you can travel across galaxies in your lifespan with ease. So for all intents and purposes, you can go faster than the speed of light provided we everything from your point of view (which is all that matters). We define speed as the distance to your destination measured in an inertia frame, divided by the time it takes you to get there, all measurements from your perspective.

the way reletivity is taught totally confuses people on this point: A HUMAN COULD EASILY TRAVEL ANYPLACE IN THE MILYWAY WITHIN THEIR LIFETIME WITH EXISTING TECHNOLOGY, except for the part about bringing your own fuel. we just don't know how to bring enough fuel to maintain a 1g acceleration for 50 years. This is why these new reactionless EM drives that NASA and others are toying with are really interesting. No doubt they are bullshit since they seem to defy newtons laws, but if it turns out they work.... see you on on the other side of the galaxy baby.

Re:C is not what people think it means

[Lumpy]

Or the pesky part that at relativistic speeds hydrogen atoms rip through the ship as if it was tinfoil.

Re:C is not what people think it means

[firewrought]

except for the part about bringing your own fuel

And the part about obliterating your spacecraft by colliding with interstellar dust at super-high relative velocities. The speed limit for arriving in one piece is way lower than c.

Re:C is not what people think it means

[sconeu]

Bzzzt!!! Thank you for playing. Here's your lovely parting gift.

Let's rephrase... as an outside observer sees you go faster you get compressed to THEM.

From your frame of reference, the outside world is going faster and is compressed, so the distance to the star that is 100 ly away gets compressed by the gamma coefficient.

Re:C is not what people think it means

[PPH]

so the distance to the star that is 100 ly away gets compressed by the gamma coefficient.

So, at .99c, what I saw as 100 ly standing still becomes 10 ly and I cover that in 10.1 years (my time). I just traveled at 9.9c (as I measure it).

I just traveled faster than light. Not the light coming out of my headlights. But in terms of distance divided by time (my time).

So if we fill space with water...

[Dareth]

So if we fill space with water... we can have fast space travel.

Re:You don't have to go faster

[prisoner-of-enigma]

How exactly is space expanding, and what exactly is expanding into?

This is difficult to answer without getting into a long discourse on spacetime. However, you have to get away from the notion that there is some kind of "edge" to the universe and space is somehow expanding that edge into infinite nothingness. There is no "edge" to the universe anymore than there is a definable "edge" to our planet (i.e. a flat earth).

Missed an example

[GlobalEcho]

Just-in-time optimized code goes faster than c.

:-)

There may be a way

[PPH]

But I'm not sure TFA deals with it. Nothing can travel faster than c in a vacuum. Light travels at c (in a vacuum). However, light cannot escape from inside a black hole. This isn't due to classical speed limits, but the way space time curves near the black hole's event horizon.

However, gravity can escape a black hole. Otherwise, how would they exist and grow? So gravity is not constrained by the same space-time curvature as light. Therefore, over long distances, the curvature of space time (even a slight effect caused by the masses of nearby galaxies) would cause the vacuum velocities of gravity to excced that of light. Or, to put another way, the path through space time for light is slightly longer than that for gravity. So gravity gets there first.

Hint: Think about this effect as an alternative to dark matter/energy.

The Usenet Physics FAQ did it better

[AdamHaun]

For a more thorough and slightly more technical approach to the same subject, check out the Usenet Physics FAQ's article "Is Faster-Than-Light Travel or Communication Possible?". Here's the conclusion:

To begin with, it is rather difficult to define exactly what is really meant by FTL travel and FTL communication. Many things such as shadows can go FTL, but not in a useful way that can carry information.

There are several serious possibilities for real FTL which have been proposed in the scientific literature, but these always come with technical difficulties.

The Heisenberg Uncertainty Principle tends to stop the use of apparent FTL quantum effects for sending information or matter.

In general relativity there are potential means of FTL travel, but they may be impossible to make work. It is thought highly unlikely that engineers will be building space ships with FTL drives in the foreseeable future, if ever, but it is curious that theoretical physics as we presently understand it seems to leave the door open to the possibility.

FTL travel of the sort science fiction writers would like is almost certainly impossible. For physicists the interesting question is "why is it impossible and what can we learn from that?"

Re:I am surprised that it did not mention tachyons

[Pro-feet]

Tachyons are nasty negative mass states; really just weird mathematical solutions. You would expect the Spanish inquisition more than the observation of a tachyon anytime soon.