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  • In Star Trek, if the Enterprise needed to talk to Starfleet Command, they could just

  • send a quick message or have a conversation in real time, even if they were light-years

  • away from each other.

  • But like most things in Star Trek, that's not how it works in real life.

  • For one thing, the waves that carry messages can only travel as fast as the speed of light,

  • or about 300 million meters per second -- and that may sound really fast, but space is also really big.

  • And as a spacecraft gets farther away, it becomes harder for us to detect its signal,

  • so we need bigger and bigger detectors.

  • Since we're still focusing on exploring our own star system, that's not a big deal right now.

  • If we ever sent a probe to another star, though, we'd need a detector the size of a city

  • to get any data from it.

  • But scientists are already working on a solution for that!

  • And it might involve using the Sun as a giant lens to strengthen the signal.

  • When you think of a lens, you might think of a curved piece of glass that can magnify

  • objects, like a telescope.

  • But the Sun actually creates a lens of its own, called a gravitational lens, because

  • huge objects like stars have so much gravity that they warp and curve space around them.

  • Isn't that just the coolest thing in the universe?

  • When those stars curve space, any radiation traveling toward them -- like light from a

  • distant galaxy -- gets curved, too.

  • The star bends the light around itself like a giant lens, and if you looked at the star

  • from a distance, you would see a magnified, distorted ring of light around it.

  • It sounds kind of complicated -because it is.

  • But gravitational lenses are super useful because they allow us to see distant objects

  • that would normally be blocked by big stars or clusters of galaxies.

  • And because gravitational lenses bend any kind of radiation, not just visible light,

  • they could also be used to magnify radio waves or other communication signals!

  • If a spacecraft around another star shot a message right at our Sun, the Sun's gravitational

  • lens would magnify and boost the signal so we could pick it up.

  • It wouldn't speed up the message, because the signal would already be traveling at the

  • speed of light, but it would make it stronger, so we could send more data and detect it more easily.

  • We have a whole lot of work to do before we're ready for that, though.

  • The main problem is that we wouldn't be able to just use a big receiving dish on Earth

  • like we do with missions today.

  • Like others lenses, the lens created by the Sun has a focal point -- a place where all

  • of the waves of radiation come together.

  • The Sun actually has a bunch of focal points, or a focal line, but the closest place to

  • pick up a signal is over 80 billion kilometers awaymore than 550 times the distance

  • from the Earth to the Sun.

  • Compare that to the Voyager 1 probe, which is about 21 billion kilometers away.

  • That's the farthest we've ever sent anything into space, and it took 40 years to get there.

  • And to use the Sun for long-distance communication, it might actually be even better to go farther

  • than 80 billion kilometers, because that would help us avoid solar flares and other interference

  • from the Sun that could scramble communications signals.

  • On the other hand, if we're at the point where we're able to send missions all the

  • way to other stars, maybe getting to 80 Billion kilometers out wouldn't be much of a problem.

  • We'd also have to figure out how to reconstruct the message we received, though.

  • The signal would be warped by the Sun's gravity, so we'd have to do a lot of math

  • to make sense of the jumbled messages we got.

  • On top of that, we'd only be able to get messages from spacecraft on the exact opposite

  • side of the Sun from our receiving probe.

  • And if we wanted to send a message instead of just receiving one, we'd also have to

  • get the faraway spacecraft somewhere on the Sun's focal line so it could pick up our

  • signal, which is pretty limiting when you're trying to explore strange new worlds.

  • So we have our work cut out for us.

  • But some astronomers think it could definitely happen, and that one day, we might have a

  • huge interstellar communications network using gravitational lenses across the galaxy.

  • Astronomers can't help but dream big.

  • But even if we never figure out how to visit other stars, we could at least use the Sun's

  • gravitational lens as a big telescope.

  • Instead of translating messages and getting the probes in the right spots, we could just

  • use the lens to get a close-up view at whatever is directly behind the Sun, like exoplanets

  • or distant galaxies.

  • It would be like having a telescope with a lens more than a million kilometers across!

  • But either way, we're definitely not ready to use the Sun as a gravitational lens for

  • anything yetlet alone interstellar Snapchat.

  • Thanks for watching this episode of SciShow Space, brought to you by our awesome patrons

  • on Patreon who make everything at SciShow possible.

  • If you'd like to help us keep explaining ideas like this, you can go to patreon.com/scishow.

  • And for more episodes about the universe and the sun which makes everything we do possible

  • also, you can go to youtube.com/scishowspace and subscribe.

In Star Trek, if the Enterprise needed to talk to Starfleet Command, they could just

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恒星間通信の未来 (The Future of Interstellar Communication)

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    林宜悉 に公開 2021 年 01 月 14 日
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