
Stephen Hawking on time travel, M-theory, and extra terrestrial life - zoowar
http://arstechnica.com/science/2012/07/steven-hawking-on-time-travel-m-theory-and-extra-terrestrial-life/
======
cletus
The odd thing about the universe seems to be that the distances are so vast
that it almost doesn't matter if there's other sentient life here or not
because it's far too distant to be of any relevance.

Travelling between stars is incredibly expensive (in terms of pure Joules) and
time-consuming. I can see the logic in the theory that the most likely outcome
for any species reaching sentience is to destroy themselves. either through
direct means (eg nuclear or biological war) or indirectly (simply running out
of resources)

~~~
Fizzer
Calling it irrelevant just because you can't travel there is short-sighted. We
could still learn a lot just by watching the broadcasts of another
civilization, even if they're already long gone.

~~~
vibrunazo
Out of all infinite amount of different methods to communicate and broadcast
themselves they could possibly be using. Including the ones we didn't even
discover yet. Assuming they're using the same ones humans just found out in
recent history. The ones SETI is measuring. Even then, assuming it's formatted
in a way we would decipher and be able to understand its structure (as in Carl
Sagan's movie). That just sounds so improbable.

Even if they are broadcasting it, we're probably listening to it with the
wrong technology. Even if we happen to be lucky of listening with the "right"
technology. We probably wouldn't be able to tell it from random noise.

I find it extremely unlikely humans will ever be able to watch alien
broadcasts during our existence in the universe.

~~~
lusr
I don't think there are many different ways to encode meaningful information.
We all live in the same universe and I see no reason to believe that
intelligent alien life won't be intellectually quite similar to us. While
tricky without context, decoding extraterrestrial signals will inevitably
produce something of interest (images, audio) even if understanding e.g. the
audio itself will be tricky.

That being said, while I suspect that meaningful, structured information will
be, by definition, structured and therefore obvious to spot in a broadcast,
the real problem is that these transmissions are likely to be (a) compressed
and/or (b) encrypted.

While compression formats may reveal a few hints that there is some structured
information present, encrypted data will be all but impossible to distinguish
from random transmissions. We may be picking up transmissions from alien life
but be unaware simply because the data is encrypted.

I have no idea what proportion of our broadcast signals are encrypted today,
but I suspect it's a fairly significant and growing proportion (privacy and
intellectual property concerns being the primary reasons).

~~~
mistermann
> While tricky without context, decoding extraterrestrial signals will
> inevitably produce something of interest (images, audio) even if
> understanding e.g. the audio itself will be tricky.

Serious question: How is it presumably simple to decode images and audio, but
difficult to understand the audio? Is it because one can assume image
representation would tend towards mathematical efficiency, but spoken
languages do not?

>While compression formats may reveal a few hints that there is some
structured information present, encrypted data will be all but impossible to
distinguish from random transmissions. We may be picking up transmissions from
alien life but be unaware simply because the data is encrypted.

I would think that encrypted transmissions would be easily distinguishable
from background white noise, no? My thinking is, you have the general random
noise of space, and then you would have something obviously different, is that
totally not the case?

~~~
lusr
Yes, I believe that images (encodings of electromagnetic radiation of
particular wavelengths) and audio (encodings of mechanical waves of pressure)
are universal concepts aliens are also likely to be familiar with, whereas
understanding the information encoded within the transmission requires
interpretation within a context we are highly unlikely to have here on Earth.

This is just my intuition and speculation but I would guess somebody could
formalise some support in terms of Kolmogorov complexity
(<http://en.wikipedia.org/wiki/Kolmogorov_complexity>): there are only so many
ways to represent an image or audio, and over time an intelligent race will
discover the least complex method and use it. Therefore, alien races of
equivalent levels of technical advancement in a given field should be able to
decode raw (uncompressed and unencrypted) transmissions of common types of
information (images, audio).

Any additional complexity on top of this method will probably be quite
structured, e.g. with television signals we have portions of the signal that
are blank because during that time the CRT of old televisions would be
retracing and not displaying data. (Actually, I believe these "dead" portions
of the video signal are sometimes used to send additional structured data,
e.g. Teletext, which would make the structure of the signal even more
apparent.)

I suspect it'll be much easier to look at alien video transmissions and figure
out what they're about than trying to listen do the same with audio
transmissions because video would provide objective context (assuming it's not
just a video of talking alien heads, or whatever the equivalent of a "head"
for them would be).

With respect to encrypted transmissions, if the entire protocol is encrypted
from start to finish, and you're using the right cipher* then no, you can't
distinguish encrypted data from random noise. This is the principle behind
TrueCrypt's hidden volumes (<http://www.truecrypt.org/docs/?s=hidden-volume>).

* What's the right cipher? So far no nobody has found a distinguisher for AES, and that's in common use, so that's probably good enough to make an alien race blind to us; i.e. we could be picking up signals from a race as sophisticated as c. 1998 humans (<http://en.wikipedia.org/wiki/Advanced_Encryption_Standard>) without realising it.

~~~
caf
Note that encrypted traffic, indistinguishable from noise, is almost always
then encoded for transmission in a format that contains redundancy
(frequently, there are more than one such layer).

For example if you electrically sniff an ethernet cable over which only SSL
traffic using AES is being sent, the first thing you will notice is a
concentration of energy near 200Mhz. Then you may see bursts of a Manchester-
encoded signal; further study reveals the regular structure of Ethernet
headers and trailers, along with IP, TCP and SSL headers. Only within that
will you hit a brick wall at the AES data itself.

Even if the payload is encrypted it should be possible in most cases to detect
a modulated transmission.

~~~
lusr
That's a good point. In effect, if we look at this from the perspective of the
OSI model, you're saying that whereas the application layer may contain
encrypted data the lower layers may contain structured data. So the logical
question that follows: is there any reason to believe aliens might use
encryption all the way down to the data link layer? Maybe our neighbours are
all at war and need to disguise and protect signals from each other?

Have you read ithkuil's comment? <http://news.ycombinator.com/item?id=4188160>

~~~
caf
Yes, but spread spectrum modulations are very much a minority among all our
transmissions, so I see no reason to expect any different from other
civilizations.

~~~
ithkuil
Today yes. But imagine that our technology gets refined in the following 10k
years, even assuming no more technological breakthroughs, but only incremental
improvements.

Even today we use some technology which is not really necessary to solve a
given problem, just because it uses off the shelf components which are cheaper
even if more complicated (e.g. a embedded cpu instead of dedicated and simpler
electronics)

------
Xcelerate
I've been watching his "Into the Universe" series, and honestly I have been a
bit disappointed. I was hoping for more science -- details about subatomic
particles, a discussion of the various interpretations of quantum mechanics,
an introduction to M-theory (that doesn't involve violins and floating
colors). Instead, one whole episode was devoted to ragging on religion -- a
bunch of speculation that doesn't teach any of the interesting science to the
show's viewers.

How about an introduction to Hawking radiation, the holographic principle,
superpartners? At least an overview of the standard model? Nope. Just reasons
"God isn't necessary". I'm not sure why he takes this route for the show.
Maybe it gets more viewers and more controversy. It's sadly reminiscient of
the history channel. It used to be full of a lot of interesting, objective
content about -- believe it or not -- history, but now it's just full of alien
speculation and religious prophecies.

~~~
rewind
It's not a show about science; it's a show about ratings. Popular science gets
ratings, which are still less than non-popular-related shows, and which are
far higher than any hard-science-related shows could ever get. You'll have to
scratch that itch somewhere else... though I totally agree with you!!!

------
vibrunazo
I love Hawking. But unfortunately, this interview is too short, simple and
obvious to be interesting. Reminds me of:

<http://xkcd.com/799/>

------
hobin
I don't really see how this is news.

Don't get me wrong, I think Stephen Hawking is a very smart man, and he has
definitely done his fair share of work to help people understand science - not
to mention that his scientific accomplishments aren't bad, either. That being
said, there's just nothing new in this Q&A that he hasn't already said or
wasn't already widely known to anyone who bothered to do a quick search on
Google (except perhaps the part about his quality of life, but let's face it,
that's not important).

~~~
pvarangot
I don't think the part about his quality of life is not important.

Lots of people have disabilities, only accounting for spina bifida which is
physically less disabling that ALS, or muscle atrophy which leaves cognitive
capacity intact, already puts them in the thousands. Someone needs to show
them they can achieve many of what they dream about, because most of society
only gives them pity and consent. We have Olympic Games for disabled people
whose dreams are of being athletes, and we need people like Stephen Hawking to
show disabled wannabe scientists and hackers (many of whom I believe read HN
and ars) that they can also triumph in their geeky endeavours.

~~~
hobin
You raise a valid point. If that were the case, though, then I would argue the
article should've been posted under a different title. The current title
suggests that I'm going to see mr. Hawking say something profoud about time
travel, M-theory and extraterrestials.

------
mbenjaminsmith
I'm surprised to hear someone of his intellectual caliber resort to ridicule
when someone brings up UFOs. UFOs "appearing" to "cranks and weirdos" doesn't
really describe the phenomena, as anyone who spent more than 30 minutes on the
subject would know.

I'd would have loved to have heard him debate the late John Mack (Harvard
Medical School, won a Pulitzer) on the subject. It's incredibly arrogant for
him to think that he can ignore the research of other academics (or remain in
ignorance of it) and still speak authoritatively on the subject.

I don't expect him to champion the field but since he's asked so frequently
about extraterrestrial life and/or UFOs it would be nice if his canned
response was a bit more intelligent.

It's incredible to dismiss so much theoretical/speculative physics in the
interview and at the same time say that maybe M-Theory will tie up the loose
ends in the Standard Model, but then again, maybe it won't and we'll be back
to the drawing board. Even though we admittedly don't understand the universe
with any degrees of completeness, obviously these popular ideas are false
based on our understanding of the universe?

~~~
rimantas

      > doesn't really describe the phenomena, as anyone who
      > spent more than 30 minutes on the subject would know.
    

It actually does.

~~~
philhippus
There are plenty of credible witnesses to UFO sightings. The problem is people
getting their knickers in a twist over the acronym 'UFO' - a product of
societal conditioning.

------
fferen
Here's an idea that's been kicking around in my mind for a while: what if it's
not that it takes such a tremendous amount of time to travel anywhere
interesting in the universe, but that our perception of time is just too fast?
Perhaps to an alien race a thousand (or million) years seems like a second.
Wikipedia suggests that our perception of time does get (slightly) slower as
we age [1], so maybe living significantly longer could do this to us as well.
Finally, it seems that our perception of time is largely shaped by the
Circadian rhythm; if life evolved somewhere with a much slower "cosmic clock"
could that also cause a much slower time perception?

[1]: <http://en.wikipedia.org/wiki/Time_perception#Long-term>

~~~
dr42
While our perception of time night be subjective, as you suggest, the
distances involved are not. Even if it only feels like a few moments, the
universe doesn't much care how we feel, or what we perceive.

~~~
fferen
Well, yes, obviously, but it would certainly affect how we (read: aliens)
approach space travel psychologically, and thus to a certain extent its
feasibility - a trip across the solar system could seem like a trip across the
street.

------
elorant
Everyone interested in the possibility of alien intelligence should read about
the Fermi Paradox: <http://en.wikipedia.org/wiki/Fermi_paradox>

It is a collection of theories that try to explain why we haven't been
contacted yet by aliens.

There is also a very good book on the subject that elaborates further on the
theories of the Fermi paradox. In total there are 50 different theories, from
life been too young on the universe and thus we're rather alone, to not be
able to communicate because they're using superior technology.
[http://www.amazon.com/Universe-Aliens-Everybody-Solutions-
Ex...](http://www.amazon.com/Universe-Aliens-Everybody-Solutions-
Extraterrestrial/dp/0387955011)

------
huhtenberg
> _I have experimental evidence that time travel is not possible. I gave a
> party for time-travelers, but I didn't send out the invitations until after
> the party. I sat there a long time, but no one came._

Why would one need to send invitations if the outcome is already known once
the party is over? It seems that merely giving a party for time-travelers is a
plenty sufficient evidence.

> _Another frightening possibility is intelligent life is not only common, but
> that it destroys itself when it reaches a stage of advanced technology._

Or that it transcends beyond physical 3D realm (as corny as it sounds) and so
it's no longer detectable from within it.

~~~
CJefferson
> Why would one need to send invitations if the outcome is already known once
> the party is over?

Well, if you didn't invite anyone, maybe the reason no time-travellers came is
that they weren't invited?

------
verroq
Is it possible that in another universe, time travel is possible and Steven
Hawking had the most awesome party imaginable?

------
DrewChambersDC
Lets be honest, there's obviously other intelligent life in the universe.
There's probably tons of it, I don't think it's ever visited earth before, and
we'll likely never shake its hand, but its out there. One day we can hopefully
communicate with one, it would have to be done with radio signals over
generations, but it would be amazing to see it happen.

I've always thought it more likely than the fact that intelligent
civilizations destroy themselves is the fact that intelligent civilizations
are out there and the really smart ones actually know the Earth exists.
Interstellar distance is likely a problem that no one has truly solved but I
like to think there's civilization out there that knows the Earth exists and
is ripe for life, just they're too far away to do anything about it.

~~~
rimantas
Obviously? Like I go outside and there it is— obvious non-terrestrial
intelligent life? For me it obviously does not exist. It may exist somewhere
in the galaxy far away. It might not. We don't know. We will never (by never I
mean ~1 billion years) know. I am amazed to see so much wishful thinking and
ignorance regarding physics and astrophysics.

------
olalonde
This comment seriously made me laugh out loud:

Maybe they like a higher CO2 level and warmer temperatures, and are
masquerading as energy company executives. Alienforming a planet is easy if
you can get the natives to do it for you.

------
ChrisNorstrom
We will NEVER be visited by extra terrestrial life. The amount of luck
required is too great. It's extremely unrealistic and foolish.

1) We need to come to the realization that it is and always will be impossible
to travel at the speed of light or anywhere near the speed of light. Doing so
would cause radiation particles, micro particles, space dust, and other little
things floating around to hit the the crew and ship at extreme speeds and rip
the ship apart. A bullet fired from a high powered rifle is only going 1,200
mph and can rip through metal. So imaging your space ship getting pummeled by
particles at 670,616,629 mph and the faster you go the more particles you got
bombarded with. There are no metals or materials that can sustain this type of
damage because these radiation particles are SMALLER than x-ray particles so
they'll pass through absolutely everything. And nothing can filter out or
block this astronomical amount of radiation that will pummel the crew. We can
wish and hope but it's a problem that is out of our control.

2) We need to stop falsely and foolishing assuming that there are aliens far
out in the universe that can see us (2012) through a telescope. If you look at
the earth right now (2012) from 65 million light years away, to the extra
terrestrial, they are just now seeing light from 65 million years ago reach
them. So to them there is no intelligent life on earth yet. It won't be
another 65 million years until they are finally able to see us humans. By that
time WE or THEY will be extinct. Because WE have the same problems THEY have.
The vast majority of planets or uninhabitable and we can't travel fast enough
to reach a planet, nor evolve or adapt to the bacteria on that planet fast
enough to actually live on it.

3) We will most certainly never be able to "move homes" to another planet
because the bacteria and organisms on it would be hostile to the point where
we can't even safely evolve around it. We can live on Earth because for
millions of years our ancesters have built up immunities to all the nasty
viruses and plagues and flus that have come and gone. If an extra terrestrial
landed here on earth they would not be able to interact with us in ANY way
without wearing a bio-suit. They can't breathe our air or drink our water. And
you think they're going to travel millions of years to get to a planet they
can't even vacation on or enjoy or interact with in any way.

4) Extra terrestrial life that is more advanced than us has no reason to go on
a suicide mission to come see us (a bunch of war-mongering primitive hairless
baboons)

To any potential aliens who are living millions of years away, we haven't even
evolved yet. By the time they see us, we will be gone. By the time they travel
millions of light years to finally reach us, both of our species will be dead.
Us from extinction and them from getting blasted by radiation. Also, if they
are more advanced than us why the hell would they want to come all this way to
see us?! That would be like us traveling millions of years on a suicide
mission to go see a planet of lemurs.

~~~
andrewflnr
Most of your points are sound, but I think you are too pessimistic about them
being interested in us. Mightn't they be just as desperate as we are to not be
alone?

~~~
backprojection
exactly.

> Extra terrestrial life that is more advanced than us has no reason to go on
> a suicide mission to come see us (a bunch of war-mongering primitive
> hairless baboons)

Just as advanced western scientists have no interest in going on biology field
trips to remote parts of the world to study lesser species.

~~~
ChrisNorstrom
Traveling on your own planet (which is easy and cheap) and traveling to an
unknown planet in space which costs trillions of dollars and takes a minimum
of 20,000 years are two very different things. Lets keep things in perspective
now.

Traveling a few hundred miles to see a creature you can stand a few feet away
from, touch, and study /AND/ traveling for millions of years, never seeing the
fruit of your labor so that your great X 1,000 grandchildren might be able to
reach a planet they can walk around on in an air tight suit for the rest of
their lives, then send a signal back to earth which will take 20 years to
reach. That's a whole new "field trip".

~~~
galadriel
Where are you getting this stupid 20,000 year figure from? Even with current
tech, we can travel at 0.1c easily, that is without any extra effort made in
actually travelling outside our solar system. Near-by candidates are within
20ly, so at min it would take just 200 year, or 3 human generations.

And if it might give you some peace, there are thing called machines that can
be built to contact other civilization without sacrificing your hypothetical
children.

~~~
rimantas

      > we can travel at 0.1c easily
    

Can we? I mean as humans, not just some spacecraft. We can also sustain closed
ecosystem for three generations? Last I heard an attempt to do that on Earth
failed.

~~~
mkramlich
> We can also sustain closed ecosystem for three generations? Last I heard an
> attempt to do that on Earth failed.

Most things fail before they succeed.

------
Variance
I'd say that the chances of us ever coming into contact with intelligent life
are worryingly low until well (as in, billions of years) into the future. If
we say that "ultimate maturity" of a civilization is to have a technological
singularity of some sort, resources wouldn't really be an issue. SETI hasn't
picked up anything. Assuming that the universe is infinite in extent, as it
currently is hypothesized to be, the only real solution is that life is so
spread out as to be almost irrelevantly far away.

~~~
rimantas
We don't have billions of years. We maybe have one billion.

------
jpeg_hero
Pithy.

