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Comment by kstrauser | Hacker News Reader

Real answer:

I absolutely love being alive right now. A Higgs boson! Confirmed objects from outside our solar system! A real life picture of a black hole! We’re just at the start of being able to learn these things, and it’s getting better by the year. I love it.

Conspiracy answer:

The alien probe launched 10,000 years ago just determined that either:

1) Our atmosphere is sufficiently thick to cause the object to disintegrate over seconds instead of instantaneously, meaning there’s enough raw gaseous material to be interesting, or

2) We have an active defense system, meaning the local inhabitants are smart enough to be interesting.

In 46 years, when the light reaches its origin around 26 Draconis, observations will be recorded, reports will be filed, and plans will be made.

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Sending probes is dangerous. You never know who is going to capture it and figure out where it was sent from. Conclusion: make deniable self-destructing probes.

1. Send probe to star system slow enough to be random interstellar rock on a collision course with planetary body,

2. it collects data as it approaches body,

3. then have it self-destruct in the atmo destroying all technology and information in the probe. Use the energy from the destruction to send a message back on a wide cone that can be intercepted.

Sadly, the combination of "wide cone" and "detectable from light-years away" implies some fairly prohibitive energy requirements.

That's according to our knowledge and understanding. It may not be the same for a civilization that is advanced enough to send such a probe.

Conservation of energy is pretty fundamental. If we can't rely on that, then there's no point assuming anything at all, certainly not alien intentions.

i would imagine intentions could be derived from resource scarcity or abundance.

If aliens intend to invade over resources, the cost of such an invasion (from an energy consumption perspective) is so prohibitively high, that harvesting from a closer body seems way more feasible.

If aliens intend to invade over not resources, but some other factor, then we cannot guess it. May be there's what amounts to religion and the invasion is a defacto purging or converting of alien species over to their "god". Or to exterminate any possible future competition (aka, darwinianism at the galactic scale).

How can you assume resources scarcity if energy isn't conserved? At this point all bets are off.

How do we know that traveling closer in the same time takes less energy than traveling further? We can't assume that anymore.

And so on. This is my problem with most sci-fi. They take some crazy assumptions and ignore most of the consequences so the world is recognizable.

This is like people in ancient Greece hearing that one city in 21st century has more population than the whole world in their time and wondering how we feed our horses :)

Or they needed a lot of paperclips

Dunno, take say 1 gram of matter and convert it to energy. Then assume something 100x better than the JWST, add in a few more decades of signal processing, encoding, etc. Add in the possibility of receiving from more than a single solar system.

After all some random ham in 2005 set a record of 13M miles per watt. That's in 2005, with an standard radio (elecraft k1) and not any exotic receivers like say something 100-1000x better than the JWST that's I'd expect earth to have over the next few decades, let alone some other civilization that's sending sensors to likely millions of solar systems if they found us.

That's only 400kw for a light year, not that much assuming you are slinging sensors into other solar systems.

Well, the energy requirements for wireless communication go up with the distance squared. So even if you can transmit 13 million miles per watt, that's equivalent to about 200GW for 1 light year.

Assuming omnidirectional transmissions, yes.

If you spread the energy out it will spread in a shape with area proportionate to the square of the distance.

You can focus more of that power into a particular area, but the fundamentals here are not particularly negotiable.

> Sending probes is dangerous. You never know who is going to capture it and figure out where it was sent from.

I'm not sure capture would necessarily be all that likely. Assuming a flyby and not a crash, capturing a probe would require the captor to accelerate to the probe's relative velocity first. If you wanted to bring it back, too, you'd then have to decelerate back into a non-escape velocity with the captive in tow.

Alternatively, you'd need some way of slowing the probe down without touching it, e.g. with light, but doing that would take a rather long time, especially if it wasn't designed as a light sail intended to be slowed down and you don't want to destroy the probe in the process.

Both sound quite nontrivial especially if the probe is travelling at a speed that would be useful for interstellar travel, and if you don't detect the probe a lot in advance, which also sounds nontrivial. If the target world had reached such an advanced technology level that the probe could be detected and deemed interesting early on and captured, all bets would be off anyway.

> Use the energy from the destruction to send a message back on a wide cone that can be intercepted.

Energy from destruction tends not to be very organized. How would you use that energy for sending a coherent directed message that isn't even known in advance (assuming it would actually transmit some of the newly collected data and not just "bye bye")?

> I'm not sure capture would necessarily be all that likely. Assuming a flyby and not a crash, capturing a probe would require the captor to accelerate to the probe's relative velocity first. If you wanted to bring it back, too, you'd then have to decelerate back into a non-escape velocity with the captive in tow.

This is a really good point. If you can make your probe fast enough you reduce warning time and make it very expensive to catch.

> Energy from destruction tends not to be very organized. How would you use that energy for sending a coherent directed message that isn't even known in advance (assuming it would actually transmit some of the newly collected data and not just "bye bye")?

I was assuming a signal that could not be distinguished from an explosion much like how cryptography can encrypt a message that without the key can not be distinguished from random noise.

If one wanted to get really deniable about this you could just design a rock such that its shape and composition would reveal facts about the planets atmosphere based purely on how it explodes, e.g. the wave lengths of the light of an explosion vary based on oxygen content. If the rock doesn't explode on schedule you could conclude with some probability intelligent life intercepted it for study.

> In 46 years, when the light reaches its origin around 26 Draconis, observations will be recorded, reports will be filed, and plans will be made.

This gives me Douglas Adams vibes, thinking about an alien species posting plans to invade Earth. "The plans were on display for months" [1]

[1]: https://www.goodreads.com/quotes/40705-but-the-plans-were-on...

“Well, crud. The survey showed that the shortest route isn’t completely clear.”

“Should we report this?”

“You really want to do all that paperwork?”

“Bulldozer it is.”

"Do you have any idea how much damage this bulldozer would suffer if I let it roll right over you?"

Absolutely none.

It especially reminds me of the Grebulons from the final^H^H^H^H^Hfifth book in the series, whose ships computer was damaged in transit, corrupting the mission directive and the memories of the crew. All they could figure out was that they should monitor the earth from a safe distance, so they set up a base on the tenth planet Rupert and watched earth TV all day.

Isn't it the fifth book in the trilogy?

Yes, the fifth book in the increasingly inaccurately-named Hitchhiker's Guide Trilogy.

The 'final' was meant as a sly dig at Eoin Colfer's addition to the series, "And Another Thing", which attempted to wrap up the story after Adams' death. I read it shortly after release and didn't give it a fair chance.

That quote is about planning a terrestrial road.

This quote is about planning an interstellar invasion: https://www.goodreads.com/quotes/5942504-the-mighty-ships-to...

Could you imagine trying to aim something at a moving planet from light years away and while also shooting it at that speed and not having potential a huge number of things affect it's trajectory via gravity? I love the conspiracy theory, but unless it could course-correct during flight, the odds seem insanely low for it to be a alien test probe

If I was an alien engineer trying to aim something at a moving planet light years away while also shooting it at that speed and having a huge number of things affect it's trajectory via gravity, I'd make it course-correct during flight.

"The navigation stage was released about Jupiter, as planned. They will ask for centuries who threw that rock, bhahaharaH!"

You can go a step further. Use a computer vision algorithm to find planets, and then do some spectroscopy to identify planets with water in their atmosphere. Course correct to aim at one of those planets

Why are we assuming it couldnt course correct?

They said it looked like a comet, not a rocket, it was very small in size.

Well, they’re cleverer than us. They probably just plugged the numbers into the n-body equation they teach in their junior high schools.

Also:

- The ion thrusters were small enough to completely disintegrate on impact/reentry.

- Oumuamua was the mother ship, clearly.

Or used their quantum computers with trillions of qBits to be confident of the trajectory to the limit of their sensing ability.

It was no disintegration at all, merely a thermochemical nanomultiplication catalyst that relied on aerobreaking to generate 10^14 quantum entangled shards of spy drones. These are now permeating all multi-celled organisms, which they have adapted as co-processors. They rely on quantum-entanglement synchronized gravitational wave induction for home-world communication, but can fall back to planet-wide baseline interferometry due to the entangled nature of their origin.

This object was a probe.

Oumuamua was the mass ejected to decelerate.

Mother ship due in 10-20 years.

Ooh, strong point!

Maybe they launched millions of those things

This is the plot of the Expanse books. Ancient alien civilization loads a rock with nano-computers that take over self-replicating molecules on planets with life to build stuff, aim it at Earth two billion years ago, but it never makes it because Saturn captures it and it becomes the moon Phoebe instead.

Dunno, there's helpful photons traveling from distant points through out stellar neighborhood and to any possible observer. We are already making 3D gravitation maps of our neighborhood. Also who says there's not some minor navigational control, much like today's smart bombs. Even minor corrections made well ahead of time could greatly help the aim.

Not to mention if you are slinging probes into other solar systems you likely could send 1000x into each one, so if a few miss, not big deal.

A civilization advanced enough to launch interstellar probes and make plans on a 20k year timescale (10k years for the probe to get here, 10k years for them to get here) has no use whatsoever for the paltry resources in our solar system. Instead they could just harvest them from nearby systems or “empty” space.

They could be interested in lifeforms that might evolve into something more formidble in 20k years.

They would also evolve over that same timeframe, likely even faster since they were already more advanced in this scenario.

Perhaps they advance very, very slowly as a species, but it’s been a billion years since their technological revolution. They’re wondering how we got from AM radio to satellite communications in less than a century, and awfully worried about it.

That's an interesting point. Although if they were that advanced, they'd realize their slowness means they wouldn't get an answer quickly enough to do anything about it.

Sadly the Draconis civilization was obliterated 10 years ago, by a Supernova way too close to their planetary system. Lucky Earth Inners dodge another cosmic bullet.

(2) is more fun, and so I will actively entertain it while accepting that (1) is more likely to be true.

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