Is Faster-Than-Light Travel or Communication Possible? (1997)

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html

by neverminder • 10 years ago

74 84 10 years ago

math.ucr.edu

Zenst2• 10 years ago

Nice list and currently no. But many theory's that say it is possible, no experiments shown it to happen and indeed faster than light gets for many down to causality. Not saying it is impossible, but in theory anything is possible until proven or disproven.

Another article that raises the same question is http://www.bbc.com/future/story/20150318-will-we-ever-speak-...

Now one aspect I'll add is that it may be possible but would the integrity of the information communicated be maintained and with that it would still be a case of no.

For me a related theory is that black holes convert mass into energy and that energy dissociates with current space and time and some of that ends up at physical location in space of 0,0,0 and time 0 as that is the earliest point in time and space. That and with all black holes over time venting so to speak to that point in space in time, was the reason for the big bang. Again a theory of mine. Now in that case something from now has gone back in time and yet has it gone faster than light? Or indeed is there anything sent that is recognisable from when it entered and in that case - no. So again whilst FTL communication may be possible, the whole aspect of integrity of that communication is a whole other aspect.

Equally the speed of light, there is another theory that the speed of light has varied over time (VLS Variable light speed) and whilst some observations lend themselves to this, it is still a theory. So that is another aspect in this that needs to be factored in. In short light may of been faster in the past, or it may of been slower and that add's a whole new layer of complexity upon this issue.

Science is fun isn't it, be darn boring when we as a species learn it all, but not in any of our lifetimes and that for me is a good thing. Though like many theories and great scientists there are and still are people who just dismiss without debate and with that how many people in the past burned or killed for saying the earth is not flat. Still be interesting for constructive perspectives and debate upon this, but alas as a subject many just dismiss and blindly label. Which is sad, in any time, even today :(.

clock_tower2• 10 years ago

When exactly were people burned alive, or killed in general, for saying the earth isn't flat? The first article of the _Summa Theologica_ discusses how to prove that the world is round; no Christian took Genesis' cosmography particularly seriously until biblical literalism and the Reformation.

You might be thinking of the heliocentricism mess; but Bruno was burned for beliefs that had nothing to do with heliocentricism, and Galileo was only confined to house arrest -- and that after the Pope had tried to compromise with him, and Galileo responded by putting the Pope's arguments into the mouth of a simpleton in a revised version of the _Dialogue Concerning Two World-Systems_.

This is a tangent to your main argument, but it's an important thing to get right; you can't reach truth if you start from misconceptions...

Zenst2• 10 years ago

http://www.biographybase.com/biography/Bruno_Giordano.html

Yip your right, my mistake, good to learn. Least none can name and was indeed thinking of Bruno at the time, my bad.

Thank you for the correction and sorry for the misconception correction by me.

chopin• 10 years ago

There should be (1998) in the title.

Not that it changes much...

SFJulie• 10 years ago

He forgot the permutation operator in quantum mechanic... Where causality is put at the intrication level, and measurement of two intricated quantic system are coupled by one another if and only if you can make in the same hesienberg window of dE.dt ~ hbar/2. Hence potentially being an ansible (like in orson scott gard books. (quantum teleportation, alain aspect 1997)

The only problem is having synchronization of time over distance and hoping the dE.dt does not require exponential energy growth over intended distance of communication and that the energy per bit is not too expensive.

But yes this article was indeed done in 1998 where USA university may have discarded science from under developed countries such as France.

sevenless4• 10 years ago

The thing is that subjectively "FTL" travel, a la Star Trek, is totally possible thanks to special relativity contracting distances between objects.

A little math shows the relative velocity in which you travel one light year measured in a rest frame, in one year in your spaceship's frame, is 70.7% of the speed of light.

If you happened to be moving at the ludicrous speed of the "Oh-My-God" cosmic ray recorded in 1991, it would take you three seconds of your time to travel to the center of the galaxy.

That should be good enough for anyone!

https://www.fourmilab.ch/documents/OhMyGodParticle/

simonh2• 10 years ago

But length contraction means that, subjectively, you'll think you've only travelled a few hundred thousand kilometers.

sevenless4• 10 years ago

This explains the famous line from Star Wars about the Millennium Falcon "making the Kessel run in less than 12 parsecs". George Lucas was obviously hip to the implications of special relativity.

snarfy• 10 years ago

The center of the galaxy is 32,000 light years away. 32,000 years will have passed at the center of the galaxy by the time you get there in your 3.2 second journey. If you then turn around and go back, another 32,000 years will have passed before you get home.

It might feel more like time travel than space travel.

andy_ppp• 10 years ago

That's why it's called space-time right...

3pt141592• 10 years ago

This is one of my theories about why there isn't any alien life around. There is some party far in the future with a beacon or message that shouts "JOIN US HERE IN THE MIDDLE OF GALAXY R345Q2 10 BILLION YEARS IN THE FUTURE!"

After about 10 thousand years of hearing the beacon and being alone we finally get restless and just build a couple thousand giant spaceships and join the rest of the universe in the most cosmopolitan place ever.

dcherman• 10 years ago

What I've always found interesting (not sure if there's a name for this) is kind of the idea that if you made such a trip, you might find by the time you arrive there in 3.2 seconds, the rest of humanity has figured out true FTL travel with the technology that was developed during those 32,000 years. As a result, you arrive in what might be the equivalent of a horse and buggy at the center of the galaxy versus what everyone else is riding around in.

soVeryTired• 10 years ago

Still gonna need some inertial dampers though.

sliverstorm• 10 years ago

That bit about the particle is fascinating, but I am struggling to understand why a particle that travels at 0.99x of the speed of light is faster than a ship that travels at 1516x the speed of light. Is the Star Trek universe not subject to time dilation?

grymoire12• 10 years ago

The star trek universe is not subject to physics in general. Sound traveling without air, time travel, FTL, Newton's Law being ignored, Creating/destroying matter, "beaming" people down to a planet, etc.

cmrx64• 10 years ago

See also https://arxiv.org/pdf/1211.6468.pdf, which accompanies a theory recently published in the Archive of Formal Proofs: http://www.isa-afp.org/entries/No_FTL_observers.shtml

It states rigorously what it means to be an object ("observer"), and what it means to travel faster than light, and proves that observers cannot travel FTL. In special relativity, though, not GR yet.

simonh2• 10 years ago

I'm with Betteridge on this one.

imglorp• 10 years ago

"No."

dang2• 10 years ago

Please don't post unsubstantive comments; especially not predictable meemy ones.

aaron695• 10 years ago

Thinking you can go faster than light for communication is the same as believing perpetual motion or even being a flat earther.

You can't do it, there are no hacks to do it. It's a law of the universe. No matter how many SciFi movies tell you other wise.

I just don't get the acceptance of this anti-scientific concept.

jandrese3• 10 years ago

This is exactly right given our current understanding of the universe. FTL travel violates causality, which is a fundamental principle of the universe.

I wouldn't go quite so far as to say it's totally impossible though. There is a whole lot about the universe we don't understand and I can't rule out the possibility that there are entire branches of mathematics and physics that we don't know about.

mariodiana4• 10 years ago

Can you or someone else "explain to me like I'm five" why faster-than-light travel violates causality?

kamaal4• 10 years ago

>fundamental principle of the universe.

Fundamental principles of the universe also say heavier than air machines should be impossible.

FTL issue is the same thing. Its possible, it just won't happen in the way we might expect.

lisivka• 10 years ago

But some objects in space are already moving faster than speed of light in vacuum. [1]

[1] https://www.youtube.com/watch?v=RaELad94KZs

api2• 10 years ago

We've only been doing this science thing in a serious organized way for between 100 and 200 years depending on how you count it. It's only since WWII that we've done it in a really big heavily funded way (cold war and all that). You're probably right, but I can't bring myself to be quite as dogmatic about it.

I do very much doubt FTL, not only for the physics reasons but for other circumstantial ones. If FTL is possible then the Fermi paradox goes from being an intellectual curiosity to a near metaphysical emergency. If there is FTL then either we are absolutely alone or there are aliens everywhere and they are hiding from us or for some reason we can't see them. That's because the first expansionary intelligence to discover FTL will fill at least the galaxy if not the entire universe in a geological eye-blink. Since ubiquitous aliens hiding seems less likely, if a pathway to FTL were discovered I would immediately conclude that we are alone in the galaxy at least and possibly beyond.

ceejay• 10 years ago

Possible doesn't necessarily mean easy.

macspoofing2• 10 years ago

If FTL is possible then the Fermi paradox goes from being an intellectual curiosity to a near metaphysical emergency.

Maybe. Maybe not. This is how UFO conspiracy theorists reason - "Here are some phenomena I don't understand, I can't think of any plausible explanation for them, therefore, must be aliens".

There may be some hidden reasons why we can't detect FTL civilizations.

kirykl2• 10 years ago

if a method to violate causality is discovered on Earth it probably wouldn't lead to intelligent expansion, but mass destruction

andrewla• 10 years ago

Our galaxy is estimated to be at most around 180,000 light years in diameter.

Even at a fraction of the speed of light, the amount of time to expand and fill the galaxy is still an eye-blink in geologic time. Even in evolutionary timescales it's still an eye-blink -- the Cretaceous era ended about 66 million years ago.

I think the depressing truth is that we are alone in this galaxy. See [1] for Michael H. Hart's extremely compelling discussion of this idea.

[1] http://adsabs.harvard.edu/full/1975QJRAS..16..128H

amelius3• 10 years ago

But you can still create the illusion of moving faster than light by freezing everybody for the duration of the experiment. That might be good enough.

jerf3• 10 years ago

You don't need that. Time dilation already does that for you. There is no apparent limit to subjective velocities.

macspoofing2• 10 years ago

You are way too sure about this. Everything we know tells us that this is a fundamental limit, but we don't know everything. For example, wormholes are still within theoretical possibility. Maybe there is some exotic aspect of reality that could imply FTL travel, causality be damned.

jerf3• 10 years ago

Everything we know tells us that energy being conserved is a fundamental limit, but we don't know everything. For example, exotic physics that allows us to pull energy from the cosmological constant itself is still a theoretical possibility. Maybe there is some exotic aspect of reality that could violate energy conservation.

My point being that, yes, these two are comparable, which is what the claim you are replying to said.

In fact, belief in FTL is sillier that violation of conservation of energy. We have no evidence for FTL of any kind. We do have some reason to believe that conservation of energy is in fact violated at cosmological scales by the increasing rate of expansion of the universe. (Perhaps future understandings will resolve this apparent violation with a more complete picture of "energy", but at the moment, what we know of as energy is not being conserved at that scale.)

mikeash2• 10 years ago

Flat earthers are a totally different thing. The shape of the Earth is a fairly simple physical fact about the universe. To deny it is to essentially deny even the most basic human ability to gather facts.

Perpetual motion and FTL travel are about physical laws, which are not known in full. We've got some really good theories with a lot of data to back them up, but the facts lie in the data, not the theories. The theories are subject to refinement and replacement as better data is obtained.

It is not known that perpetual motion or FTL are impossible. It is believed that they are impossible, because the best theories to explain current data say they are impossible. But there is room for new data and new theories.

It was not all that long ago that it was "scientific fact" that atoms were indivisible (that's what the word means, even), that velocities add linearly, that light propagates through a fixed medium, that matter is conserved, and that gravitational force is proportional to mass and inversely proportional to the square of distance.

I also don't see much "acceptance" of FTL as physical fact. I see it accepted a lot as a story device, but that's just because it's handy for making entertaining stories, not because there's any basis in physical fact. There's some "acceptance" of FTL as physical fact in that people don't completely rule it out, but that's entirely justified.

Jach• 10 years ago

http://arxiv.org/abs/1005.4172

c is a bit more established than "scientific fact" like the behavior of atoms were once thought to be, it is very mathematical, as is the curvature of the earth being > 0. In principle new data could come in showing these things to be false, in the same sort of way twice 2 may not be 4.

Another similar fact almost beyond experimental disproval is https://en.m.wikipedia.org/wiki/Identical_particles

astrowilliam• 10 years ago

And in the early 1000s humans believed that we would never fly a few people strapped to a giant rocket to the moon. They believed that because the technology to do it hadn't been invented yet and we had no idea it was possible.

We have to learn how to do it and then we will do it.

michaelmrose• 10 years ago

Flying didn't violate the basis premises of physics. Also it exacerbates the issue wherein space doesn't appear to be full of aliens. Even a few races in the galaxy expanding with slower than light travel could fill the galaxy in tens of thousands of years. Now imagine how fast the universe fills up with ftl travel

Bombthecat• 10 years ago

What if physics is like a computer?

You have atoms and quants and whatnot. Now you add one and one another. You keep adding and soon or matter there is a slip. Basically you get the universe to a buffer overflow. All still following the laws of physics. Like you get a cpu limited of his numbers you get the universe to a buffer overflow.

Now one could say, but the universe is endless. Which means you would need endless energy for that buffer overflow.

But who says you need to create that buffer overflow in the whole universe and not in a cube? And who says the universe is endless?

blackkettle• 10 years ago

I don't get the thought process that locks this possibility out. Imagine you are a simulated entity inside simulated universe - v100000 of Eve Online.

There are rules that you can see and access, and those you cannot. Both are in some sense irrelevant to your own perception of truth because they are determined outside the bounds of your empirical experience.

What good evidence do you have to refute such an explanation [surely its likelihood increases in line with our own ability to create the 'next turtle down'].

brainpool• 10 years ago

If it is imaginable I believe it is possible. Within our current understanding of physics not doable, but that's just theory.

Abraln• 10 years ago

I agree with the link that it really depends on what you mean by FTL. At first glance refrigerators seem impossible because they would reverse entropy. The key is that it does not practically matter if they do or not, they just need to achieve the desired result. I would personally consider FTL anything that would beat light traveling through unaltered space-time.

dang2• 10 years ago

Two previous discussions: https://hn.algolia.com/?query=Is%20Faster-Than-Light%20Trave....

stupang• 10 years ago

You know, the Speed of Dark makes the Speed of Light look slow.

amag2• 10 years ago

And Ludicrous Speed makes Speed of Dark look slow.

Is Faster-Than-Light Travel or Communication Possible? (1997)

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