Would We See the Aliens Coming? Detecting an Extraterrestrial Invasion

UFOs! If the aliens were about to attack Earth, would we get any warning? Well, as long as the extraterrestrials obey the laws of physics, we should get a little advance notice...

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Team: Fraser Cain - @fcain
Jason Harmer - @jasoncharmer
Susie Murph - @susiemmurph
Brian Koberlein - @briankoberlein
Kevin Gill - @kevinmgill

Created by: Fraser Cain and Jason Harmer

Edited by: Chad Weber

Music: Left Spine Down - “X-Ray”
Classic sci fi trope time. The air force detects a fleet of alien spacecraft out past Jupiter, leaving enough time to panic and demonstrate what awful monsters we truly are before they come ring our bell.
Is that how this would work?

Imagine a pivotal scene in your favorite alien mega disaster movie. Like the one where the gigantic alien ships appear over London, Washington, Tokyo, and Paris and shoots its light-explody ray, obliterating a montage of iconic buildings. Demonstrating how our landmark construction technology is nothing against their superior firepower.

What could we do? We’re merely meat muppets with pitiful silicon based technology. How could we ever hope to detect these aliens with their stealth spacecraft and 3rd stage guild navigators? If we’re going to do this, I’m going to make up some rules. If you don’t like my rules, go get your own show and then you can have your own rules.

Alternately, as some of you are clearly aware, you can rail against the Guide To Space in the comments below. Dune reference notwithstanding, I’m going to assume that aliens live in our Universe and obey the laws of physics as we understand them. And I know you’re going to say, what if they use physics we haven’t discovered yet?

Then just pause this video and get that out of your system. You can make that your first decree against the state right in the comments below.

As I was saying, physical aliens, physical universe. We’ll discuss the metaphysical aliens in a magic universe in a future video. The ones that have crystals and can heal your liver through the power of song.

A basic rule of the Universe is that you can’t go faster than the speed of light. So I’m going to have any aliens trying to attack us traveling at sublight speeds.

So, we’ll say they’ve got access to a giant mountain of power. They can afford to travel at 10% the speed of light, which means before they get to us, they have to slow down.

At this speed, deceleration is expensive. We’d see the energy signature from their brakes long before they even reached Earth.

Let’s say they’re passing the orbit of the dwarf planet Pluto, which is 4 light-hours away. Since they’re travelling at 10% the speed of light, we’d have about 40 hours to scramble jet fighters, get those tanks out onto the streets and round up Will Smith, Jeff Goldblum and Bruce Willis to hide behind.

Would we even notice? Maybe, or maybe not. A growing trend in astronomy is scanning the sky on a regular basis, looking for changes. Changes like supernova explosions, asteroids and comets zipping past, and pulsating variable stars.

One of the most exciting new observatories under construction is the Large Synoptic Survey Telescope in Chile. Once it begins regular operations in 2022, this array of telescopes will photograph the entire sky in fairly high resolution every few nights.

Computers will process the torrent of data coming from the observatory and search for anything that changes. What if they engage their cloak?

Actually (push glasses up your nose) the laws of physics say that the aliens can’t hide the waste heat from whatever space drive they’re using. We’re actually pretty good at detecting heat with our infrared telescopes.

A space drive decelerating a city-sized alien spacecraft from a significant portion of the speed of light would shed a mountain of heat, and that’s all heat we might detect.

Astronomers have been searching for alien civilizations by looking for waste heat generated by Dyson spheres encapsulating entire stars or even all the stars in a galaxy. Nothing’s turned up yet. Which I for one, find a little suspicious.

If you’re from an alien race who’s planning to invade. Cover your ears. If aliens wanted to catch us off guard, they can use one of the oldest tricks in the aerial combat book, known as the Dicta Boelcke. They can fly at us using the Sun as camouflage. A rather large portion of the sky is completely obscured by that glowing ball of fiery plasma. It worked in WW1, and it’ll still work now.

[cortster]

If the aliens have the tech to get here, then we have already lost.

[Cromwell]

We are protected by Atlantis that landed in the Pacific just outside San Francisco.

[rgraph]

The forest you stand in front of looks super-serene.

[bobbobson]

Like Voyager 1 (but in a few hundred years) their spacecraft could have stopped broadcasting info to their planet, so they might not know if one of the old spacecraft had found us.

[darkstar_-hiwp]

Just wanted to say first, another great video. I do believe that we would stand a very good chance. The main reason is that even if they are thousands of years more advanced than us they can still only send a certain limited amount of objects (spaceships) to us from their star system. And they won't have the benefit of a planet (earth) to replenish or repair their ships after we target them. But we do have the benefit of earth to continue to replenish our supplies. Its the main reason why in the movie Battleship that they encased their ships behind a force field. Because they knew that even though they had superior technology we had the superior numbers and the benefit of our home planet to continue to replenish our supplies (battleships) continuously while they did not. They only had a limited number. And it had to be sent across long distances in space.

[mckmurkles]

I imagine an alien invasion being something like this: Someone says " What's that weird looking" but before they finish the sentence the earth and all it's inhabitants gets transformed into some kind of giant computer.

[Rubashow]

I think the biggest problem concerning alien invasion is the motivation. War of the worlds gave the Martians a relatively good motivation. They weren't an interstellar civilisation and Mars' biosphere collapsed, so they evacuated their homeworld for earth. There are other Alien invasion movies, like Independence day, were the aliens attack Earth for natural resorces - that you could find anywhere in the solar system without Will Smith firing nukes at you. Given the possibilities of the aliens to get resources from anywhere this is pretty improbable, unless they just liked a good killin'.

Two reasonable scenarios for alien 'iinvasions' aren't actually alien invasions. In "Roadside Picnic" the aliens never disclose their reasons for visiting earth. A scientist reasons that we are mere ants trying to comprehend camping teenagers at the roadside. We are too insignificant for them to even consider us and their visit might have been pure happenstance.

The second scenario isn't an invasion. It's just the complete annihilation by relativistic kinetic bombardement. A neighboring species, that is a few centuries ahead of us scientifically, notices us gaining the abilities to accelerate large vessels to relativistic speeds. Next thing you know they launch a couple of relativistic bombs into all larger bodies of the solar system. Their reasoning is: All spaceships venturing near the speed of light are potential weapons of mass destruction. Since the change of us using those against them either on purpose or as an accident isn't zero and the risk is total annihilation of us, we decided to preempt you. Nothing personell, kid.

[splortz]

Aliens attacking?  One word:  Chuck Norris.

Oh, that was two words...sorry.

[richardprice]

Chuck Norris on standby, he doesn't sleep waits.

[nolanjshettle]

"demonstrating how our landmark construction technology is nothing against their superior firepower"
I couldn't stop laughing after this... I'm dead

[Delosian]

'Heat' (by conduction) doesn't travel well in a vacuum because in the vacuum of space the temperature is a few degrees above absolute zero, and only travels at the Speed of Sound. What you were talking about is infra-red radiation, which travels at the speed of light, and only has an effect on that which it touches. Both follow the inverse-square law where doubling the distance quarters the power. A spacecraft producing small amounts of infra-red radiation (in relation to a star system) wouldn't produce enough heat energy to even show up on our scans until they're near Earth's orbit, and even then we would have to have something pointed in that direction to pick it up.

[bashkillszombies]

It depends on whether you're on your knees with them behind you or in front of you.

[alflud]

Okay, okay .... I'm slowly making my way through all of your videos here Fraser - they're fascinating, every one of them, thank you - but this is another one of those where I feel a comment is definitely necessary :) So you put this up in 2015 and in the time since we've seen the existence of gravitational waves being proved. You know yourself, because you mentioned it in a recent video, that the future of astronomy lies in gravitational wave detection, right?

Well, as you know, the science itself is still in its infancy, we're only able to detect medium-sized black-hole mergers because those specific events have such a huge impact on the fabric of space-time. We can't hope to detect much smaller distortions in the fabric of space-time as it is right now but wait ... wait - look, another thing that the detection of gravitational waves _proves_ is that space-time itself really is malleable. If it weren't malleable, pliable or _distortable_ (not a word)... then waves wouldn't be able to travel _through_ it.

This _is_ physics we understand. We can now detect gravitational waves. Show me a wave we've discovered that we've not been able to generate ourselves after some time? It stands to _reason_ that if we can learn to generate gravitational waves that we _will_ be able to distort space-time with them. What the effects of it may be who can say but all of this ... the reality of gravitational waves, it gives weight to the concept of a 'warp' drive - a drive that that operates by distorting space-time with gravitational waves, perhaps multiple waves either focused on a specific point or set up to interfere with each other in a certain way. I like the idea that a drive can distort space-time in such a way that it pulls the destination point to itself and when the drive 'lets go' of that point the distorted fabric around it returns to it's original shape, the point to its original location, dragging the drive and ship along with it, traveling _with_ space as opposed to traveling _through_ it and more or less instantly arriving at your destination.

I do think that as the resolution of our gravity wave detection devices increases we'll begin to see artificial distortions and that'll be our first glimpse of space-faring alien civilizations but here ... here's the interesting thought - how might a civilization that has mastered the warping of space-time use that sort of physics to hide itself from 'primitive' light/heat-seeking eyes?

[PhysicsPolice]

3:30 You might not detect the waste heat if they pointed it away from us. An incoming ship might spray out exhaust heat in a cone shape while hiding behind a cold surface i.e. a "shield" pointing towards the Earth.

[richardprice]

Hi again Fraser, I've asked you this before but you may not have seen it, why was the main fuel tank on the first launch of the space shuttle white and why did it change to the brown colour later on? This has been bugging me for years! Great channel by the

[radkonpsygami]

Like all invading armies in our history, aliens would realistically be dependent on supply lines - denying them access to critical supplies from our Earth would be a good strategy.

[czarpeppers]

1:57 An Alteran Aurora-class warship can travel a lot faster than 10% the speed of light. Jeeze!

[Oobe]

who even wants to travel at 10% the speed of light... that's like watching hair grown, it's that slow in the universe. hair grows faster.

[seanhartnett]

Exactly. If they have the technology to come here, we are doomed.

[AvyScottandFlower]

I've always thought that question is moot

Would ants be able to ready themselves against a human approaching their nest and then stepping on them?
They wouldn't even have time to learn if the human stepped on them intentionally or not... only the ones inside the nest have a chance for survival.