Placeholder Image

字幕列表 影片播放

  • Aliens contacting us might seem like science fiction but now, new mysterious

  • signals from outer space are intriguing scientists around the world.

  • This signal is so bright that it was completely unlike anything we'd ever seen before.

  • It's not crazy to think that radio bursts could be created on another planet.

  • What causes them is one of the biggest mysteries in physics.

  • Now linking strange signals from space with aliens sounds a bit like something cooked up

  • by a conspiracy theorist.

  • Yes this is real science.

  • It's the job of an astrobiologist to figure out where in the universe is habitable and

  • if possibly intelligent life could have developed there and then contacted us.

  • In fact, in 1961 pioneering astronomer Frank Drake organised and now infamous secret

  • meeting to try and figure out how many

  • civilisations like this exist outside of our own.

  • So we start out with the rate of star formation.

  • Multiply that by the fraction of stars which actually have planets, habitable planets in

  • each system, by the fraction on which life develops, the fraction by which intelligence appears.

  • By the fraction of

  • Those which actually give a detectable technology.

  • This rate times the average time

  • that these civilizations remain detectable.

  • N equals about 10,000 detectable civilisations at present

  • in our galaxy the Milky Way.

  • Calling themselves the Order of the Dolphin,

  • this group of award winning scientists, set out on the hunt for this huge number of

  • civilisations that they thought could be out there.

  • Oh I believe very strongly that they are out there.

  • We can be very very wrong and yet there will be many many detectable civilisations.

  • From secret government agencies to Nobel Prize winning scientists,

  • the search was on for weird

  • First there was the Wow signal in 1977, detected by the Big Ear radio telescope in Ohio.

  • The signal was strong about 72 seconds.

  • But more importantly it was detected in something known as the Hydrogen Line.

  • That was significant because at the time astronomers thought that if extraterrestrials

  • did exist they would use that frequency.

  • The astronomer Jerry Ehman was so excited that he actually wrote the term 'Wow!' on the

  • print out.

  • Very quickly it was dismissed by astronomers as actually coming from a comet.

  • Then in 2007 came a detection of what would become the biggest mystery in physics,

  • something that could have been a game changer in the search for aliens.

  • My student showed me this signal that was so bright and apparently so far away that it

  • was completely unlike anything we'd ever seen before.

  • Then we realise this is just impossible.

  • Unless a civilisation is way more advanced than we are.

  • Scientist Duncan Lorimer and his team had found what we now call Fast Radio Bursts.

  • They're incredibly bright radio signals so bright that they can't be coming from any

  • naturally occurring phenomena on earth.

  • They have to be coming from outer space.

  • Quite frankly it was unlike anything I'd ever seen before.

  • Yet it had all the hallmarks of a signal that was coming from deep space.

  • I did think that it could be a signal from an extra terrestrial civilisation.

  • We create signals like that on Earth,

  • so it's not crazy to think that radio bursts could be created on another planet.

  • So it was a groundbreaking time for physicists and with this new data from Lorimer the

  • burning question everyone still had was

  • Now the problem with the Lorimer Burst was that it was just a one off

  • and how do you prove a one off is real and not just some noise or some random signal in

  • your detector.

  • Well it helped when other scientists around the world started detecting signals just

  • like it.

  • They were coming from all over the sky and they were clearly real.

  • So it was a breakthrough moment.

  • Now although this seemed really exciting it meant that there were probably much more

  • likely explanations for what was going on.

  • We observe binary systems of two neutron stars that are in orbit around each other.

  • And when we observe these systems we see them getting closer and closer together all

  • the time.

  • So what will happen eventually is that they'll going to collide.

  • And when they merge the neutron stars will be completely destroyed and form a blackhole.

  • When you look at the energetics of these events you can easily explain the FRB

  • energies with them.

  • You can also explain the durations of the FRB pulses with the expected durations of

  • these merger events.

  • So it's quite a plausible explanation.

  • Neutron stars are some of the most energetic objects in the universe.

  • Second only to black holes and you need something really energetic to produce a fast

  • radio burst.

  • Now astronomers recently have discovered a fast radio burst coming from a magnetar in

  • our own Milky Way galaxy.

  • A magnetar is a special type of neutron star that has a very high magnetic field.

  • And while this is really exciting that we finally might have an explanation,

  • it means that aliens producing FRBs is becoming a lot less likely.

  • Now that fast radio bursts are real.

  • It comes back to the point where they could be caused by aliens.

  • So if I were looking for a signal from an extraterrestrial civilisation I'd be looking

  • for it coming from a single point in the sky.

  • Here we have a population of sources all over the sky which implies that the aliens are

  • all over the place, all over the universe.

  • That just seems highly unlikely to me.

  • So we're one step closer to solving the mystery of fast radio bursts even though it's

  • looking likely that they're not the alien signals that everyone was secretly hoping for.

  • But as a scientist I reckon.

  • Never say never.

  • We'll always keep observing the sky and I think in our lifetimes we've got a great

  • chance of discovering alien life somewhere out there in the universe.

  • We've done a great deal of searching in the last 50 plus years and we've learned that

  • we're going to have to search perhaps a million stars and countless frequency channels

  • before we have a good chance of success.

  • If I had this to do all over I would still do it.

  • And in fact I'd probably put more time into it because I've come to realise that's what's

  • required to succeed.

  • And to me that time is not time wasted because the eventual discovery is of such

  • importance. That it justifies

  • not just one human life being dedicated to succeeding but many.

Aliens contacting us might seem like science fiction but now, new mysterious

字幕與單字

影片操作 你可以在這邊進行「影片」的調整,以及「字幕」的顯示

A1 初級 美國腔

外星人(Are These Signals From Aliens? | Space Mysteries | Earth Lab)

  • 13 1
    joey joey 發佈於 2022 年 01 月 05 日
影片單字