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Yes, I believe there is life on other planets, intelligent life even.
I also think that the search for life elsewhere in the universe is THE most exciting scientific
exploration ever.
Why then don’t I work on it, you ask?
Well, I think I do, kind of.
I’ll get to this.
But first let me tell you how scientists search for life that’s not on Earth, or “extraterrestrial”,
as they say.
When I was a student in the 1990s, talking about extraterrestrial life was not considered
serious science.
At the time it was not even widely accepted that solar systems with planets like earth
are a common occurrence in the universe.
But in the past 10 years the mood among scientists has shifted dramatically, and that’s largely
thanks to the Kepler mission.
The Kepler satellite was a NASA mission that looked for planets which orbit around stars
in our galactic neighborhood.
It has observed about 150,000 stars in a small patch of the sky, closely and for long periods
of time.
From these observations you can tell whether a stars dims periodically because a planet
passes by in the line of sight.
If you are lucky, you can also tell how big the planet is, how close it is to the star,
and how fast it orbits, from which you can then extract its mass.
Kepler has found evidence for more than 4000 exoplanets, as they are called.
Big ones and small ones, hot ones and cold ones, and also a few that are not too different
from our own planet.
Kepler is no longer operating, but NASA has followed up with a new mission, TESS, and
several more missions to look for exoplanets are upcoming soon, for example there is another
NASA Mission W-FIRST, there is the CHEOPS mission of the E.S.A, and the James Webb Space
Telescope, which is a joint mission of NASA, the E.S.A, and the Canadian Space Agency.
So, we now know that other earth-like planets are out there.
The next thing that scientists would like to know is whether the conditions on any of
these planets are similar to the conditions on Earth.
This is a very human-centered way of thinking about life, of course, but at least so far
life on this planet is the only one we are sure exists, so it makes sense, to ask if
other places are similar.
Ideally, scientists would like to know whether the atmosphere of the earth-like exoplanets
contains oxygen and methane, or maybe traces of chlorophyll.
They do already have a few measurements of atmospheres of exoplanets, but these are mostly
of large and hot planets that orbit closely around their mother star, because in this
case the atmosphere is easier to measure.
The way you can measure what’s in the atmosphere is that you investigate the spectral composition
of light that either passes through the atmosphere or that is emitted or reflected off the surface.
For this too, there are more satellite missions planned, for example the ESA mission ARIEL.
Ok, you may say, but this will in the best case give us an indication for microbial life
and really you’d rather know if there is intelligent life out there.
For this you need an entirely different type of search.
Such searches for extraterrestrial intelligence have been conducted for about century.
They have largely relied on analyzing electromagnetic radiation in the radio or micro-wave range
that reaches us from outer space.
For one that’s because this part of the electromagnetic spectrum is fairly easy to
measure without going into the upper atmosphere.
But it’s also because our own civilization emits in this part of the spectrum.
This electromagnetic radiation is then analyzed for any kind of pattern that is unlikely to
be of natural, astrophysical origin.
As you already know, no one found any sign of intelligent life on other planets, except
for some false alarms.
The search for intelligent, extraterrestrial life has, sadly enough, always been underfunded,
but some people are not giving up their hopes and efforts.
There is for example the SETI Institute in California.
They have a new plan to look for aliens, which is to distribute 96 cameras on the surface
of our planet so that they can look for LASER signals from outer space, 24 hours a day,
all over the sky.
Like with the search for radio signals, the idea is that LASER-light might be a sign of
communication or a by-product of other technologies that extraterrestrial civilizations are using.
From those 96 cameras so far one has been installed.
The institute is trying to crowdfund the mission, for more information, check out their website.
A search that has no funding issues is the “Breakthrough Listen” project which is
supported by billionaire Yuri Milner.
This project has run since 2015 and will run through 2025.
It employs two radio telescopes to searching for signs of intelligent life.
The data that this project has collected so far are publicly available.
However, they amount to about 2000 Terabytes, so it’s not exactly user-friendly.
Milner has another alien project, which is the “Breakthrough Starshot”.
Yes, Milner likes “Breakthroughs” and everything he does is Breakthrough Something;
he is also the guy who set up the Breakthrough Prize.
The vision of the Starshot project is to send an army of mini space-craft to Alpha Centauri.
Alpha Centauri is a solar system in our galactic neighborhood, and “only” about 4 light
years away.
It is believed to have an earth-like planet.
Milner’s mini-space craft are supposed to study this planet and send data back to earth.
The scientists on Milner’s team hope to be ready for launch by 2036.
It will take 20 to 30 years to reach Alpha Centauri, and then another four years to send
the data back to Earth.
So, maybe by 2070, we’ll know what’s going on there.
It’s unlikely, of course, that we should be so lucky to find intelligent life basically
at the first place we look.
Scanning the galaxy for signs of communication, I think, is much more promising.
We should keep in mind that quite plausibly the reason we have not yet found evidence
for extraterrestrial intelligent life is that we have not developed the right technology
to pick up their communication.
In particular, if there is any way to send information faster than the speed of light,
then that’s what all the aliens are using.
And, as I explained in an earlier video, in contrast to what you may have been told, there
is nothing whatsoever wrong with faster-than-light messaging, except that we don’t know how
to do that.
And here is where my own research area, the foundations of physics, becomes really important.
If we ever want to find those aliens, we need to better understand space and time, and matter
and information.
Thanks for watching, see you next week.