
Is Faster-Than-Light Travel or Communication Possible? (1997) - neverminder
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html
======
sevenless
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/](https://www.fourmilab.ch/documents/OhMyGodParticle/)

~~~
snarfy
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.

~~~
3pt14159
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.

~~~
zxexz
Huh, this is a really fun thought experiment. Does anyone know any scifi books
that explores this (or a similar) concept?

~~~
akshayn
As vslira alluded:
[https://en.wikipedia.org/wiki/The_Restaurant_at_the_End_of_t...](https://en.wikipedia.org/wiki/The_Restaurant_at_the_End_of_the_Universe)

~~~
zxexz
Oh, I've read that five part 'trilogy' several times :) I guess I should have
said...

Douglas Adams' books have been a major fixture of my life since I was 12. He
really was ahead of his time. Actually I don't think said time he was
metaphorically ahead of has come yet :)

------
cmrx64
See also
[https://arxiv.org/pdf/1211.6468.pdf](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](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.

------
aaron695
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.

~~~
api
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.

~~~
macspoofing
>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.

~~~
api
Way off in tangent land now but: while much of "ufology" is indeed silly, "the
aliens are here but they are not communicating" _is_ a valid hypothesis for
the Fermi paradox (with or without FTL).

There are numerous rational reasons that an intelligence exploring the
universe might choose to be very very careful about initiating communication
to the point of taking steps to avoid even accidentally revealing itself. Some
of these are altruistic (e.g. prime directive and contamination concerns) and
some are self-interested (see game theory, and consider the apocalyptic
destructiveness of conflict between really advanced intelligences).

~~~
xj9
It seems implausible that all of the aliens would agree to ignore us, even
less so for them to consistently arrive at that conclusion in an independent
manner. Then again, Earth might be exceptionally boring and consistently
uninteresting to spacefaring aliens. Who knows? Maybe life is really rare.

------
Abraln
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.

------
dang
Two previous discussions: [https://hn.algolia.com/?query=Is%20Faster-Than-
Light%20Trave...](https://hn.algolia.com/?query=Is%20Faster-Than-
Light%20Travel%20or%20Communication%20Possible%3F&sort=byDate&dateRange=all&type=story&storyText=false&prefix&page=0).

------
chopin
There should be (1998) in the title.

Not that it changes much...

------
Zenst
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-...](http://www.bbc.com/future/story/20150318-will-we-ever-speak-across-
galaxies)

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_tower
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...

~~~
Zenst
[http://www.biographybase.com/biography/Bruno_Giordano.html](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.

~~~
clock_tower
Thanks for not turning it into a fight! (And I apologize for my contentious
tone; I was inappropriately gearing up for battle there.)

I thought you might be thinking of Bruno, the scientist who really was burned
at the stake; it's a good thing for everyone that this wasn't for his science.
(Of course, it would've been better if people weren't burned at the stake in
general. Certain modern elements have reminded us of how painful a death that
was...)

I also learned a few things about Galileo from Biography Base's article on
him; thanks for that link!

The more I learn about that case, the less it sounds like Religion versus
Science and the more it sounds like a conventional miscarriage of justice. A
frail, sick, stubborn old man should never have been treated like that, even
though he _did_ call the Pope a simpleton. The Pope is the Pope, and has
certain standards to maintain; it doesn't reflect well on Christ when His
Vicar abuses the courts to make trouble for people who insult him.

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

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

~~~
amag
And Ludicrous Speed makes Speed of Dark look slow.

------
simonh
I'm with Betteridge on this one.

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

------
SFJulie
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.

