Are Aliens Visiting Earth?

[echoreply]

Phil Plait summarizes a recently released simulation study (pdf).

Summary of the summary: Taking into account galactic rotation, a civilization should be able to expand into the galaxy in a few hundred million years. That is pretty short compared to the 13.5 billion year age of the galaxy.

Which, of course, comes back to Fermi’s Paradox. Why don’t we see them?

The article notes that tweaking some of the assumptions, it’s possible to get galaxy spanning civilizations that have big unexplored pockets.

[Voyager]

Since it’s been bumped.
Let’s assume that it is possible for an advanced alien civilization to cross interstellar distances without violating the rules of physics, by being long lived or by hibernating.
It is pretty certain that a spaceship that can do this would be a lot bigger than the UAEs we are seeing. So, there must be a mother ship. Where? We track things in orbit and going to orbit - since the UAEs show up on radar, we’d see them climbing away from earth to return to the mother ship.
Where is it hiding? Not on the far side of the moon, that’s for sure.
UAEs coming from inside the earth kind of makes more (but still no) sense. Or they are time machines. Incompetent ones.
When all this started it was still conceivable they came from Mars or Venus (like Adamski said.) Not any longer.

[Mijin]

@echoreply

it’s possible to get galaxy spanning civilizations that have big unexplored pockets.

Sure, but they don’t necessarily need to knock on our door. Note that any activity or structure detectable from Earth would qualify too.

So in terms of explaining Fermi, it’s not quite enough to say they haven’t been to every star. We also have to posit no megastructures, no big sources of radio waves etc etc. For millions of years.

@Voyager

being long lived or by hibernating.
It is pretty certain that a spaceship that can do this would be a lot bigger than the UAEs we are seeing

Too many assumptions.

1. A sub lightspeed craft could arrive at Earth in a short on-board time due to time dilation.
2. Probes could be arbitrarily small; the starshot project for example proposes a probe the size of a grain of rice.
3. Lots of other things we could speculate; perhaps the UAPs are launched from a mothership that remains hidden or far away.

Now, I will say what I said before: that getting to earth silently then putting on a show in our atmosphere seems inconsistent. But we can’t say much more than that.

[garygnu]

I’m of the opinion that there are multiple great filters. Earth is the only planet in our galaxy that has complex, multicellular life. Maybe 1 in 100 or even 1 in 1000 galaxies in the universe has intelligent life. Humans will never even contact another planet, let alone have visitors.

What we are seeing in these latest videos are optical illusions and/or advanced drones. That may sound flippant, but aviation technology without the limitations of human biology have been developing for decades.

[Voyager]

@Mijin

• A sub lightspeed craft could arrive at Earth in a short on-board time due to time dilation.
• Probes could be arbitrarily small; the starshot project for example proposes a probe the size of a grain of rice.
• Lots of other things we could speculate; perhaps the UAPs are launched from a mothership that remains hidden or far away.

1. That’s possible, but takes tons of energy, so it also suggests a larger ship.
2. I’m talking about the things we are seeing, all much bigger than grains of rice. Yeah, those could be passing through our solar system every week and we’d never know.
   3 I already discussed. We’d see the UAEs climbing out of our atmosphere or in space.

Arthur C. Clarke complained about how people had no idea of how far away the stars are, especially on TV. I didn’t understand until I saw a Flash Gordon TV show from 1952 which had exactly this problem. Not to mention Space 1999. The analogy he used was the view of many people was similar to a New Yorker who thought that Australia was a short hop from Staten Island.

[Mijin]

@Voyager

That’s possible, but takes tons of energy, so it also suggests a larger ship.

Or a launch vehicle, say.

@Voyager

I’m talking about the things we are seeing, all much bigger than grains of rice.

This sentence confuses me, because it’s like you’ve misparsed my point, but your misparsing doesn’t make any sense. Did you honestly think my point was that UAPs are all rice-grain sized?

Needless to say, no. It’s like this: You are saying that UAPs are too small to have travelled interstellar distances. I am saying that even probes that humans may build soon may be as small as a grain of rice, therefore probes made by aliens may be rice-grain sized, or 1-meter wide, or 5-meters wide, or just any size greater than or equal to a grain of rice.

@Voyager

I already discussed. We’d see the UAEs climbing out of our atmosphere or in space.

UAPs.
And yeah, I broadly agree, but this is a different point. As in, you were arguing about the size of UAPs, and I was listing reasons why “massive starship making slow voyage” cannot be assumed as the only way for aliens to get from star A to star B.
Now if you’re making the point that it’s strange we can see UAPs on radar, say, yet never record them leaving the atmosphere, then yes, I’d agree that’s strange. If the alien craft have any way to hide from radar, why do they ever turn it off?
But I don’t see what this point has to do with the size of the ships concerned.

@Voyager

Arthur C. Clarke complained about how people had no idea of how far away the stars are, especially on TV.

Sure, but that doesn’t apply to me. I am very interested in astrophysics and am a regular watcher of PBS space time and Astronomy with Dr Becky. I’m well aware of the ludicrous distances involved.

So I’ll counter with something else Arthur C Clarke said: “We will find apes or angels, but not men”

When it comes to space travel, humans are really, really new to this. Sputnik 1 was made in 1957, well within living memory.

Meanwhile, it’s extremely unlikely we would encounter an alien species mere centuries ahead of us technologically; they are far more likely to be millions of years ahead (or behind).

About all we can say is that we don’t expect them to have found a way to travel FTL. More than that, it’s just impossible to say. I see no reason to assert their ships will be big or small.

[Voyager]

@Mijin

This sentence confuses me, because it’s like you’ve misparsed my point, but your misparsing doesn’t make any sense. Did you honestly think my point was that UAPs are all rice-grain sized?

Needless to say, no. It’s like this: You are saying that UAPs are too small to have travelled interstellar distances. I am saying that even probes that humans may build soon may be as small as a grain of rice, therefore probes made by aliens may be rice-grain sized, or 1-meter wide, or 5-meters wide, or just any size greater than or equal to a grain of rice.

I thought you were referring to the idea of sending out many, many very small probes, with the ability to make more when some arrive at a system with the proper resources. That’s perfectly plausible. Slightly bigger than rice size ones also. But the stuff that is out there, supposedly, is way bigger than this and would have to be deliberately sent.
It does give me an idea - maybe there are UAPs but there are AIs on board, not aliens. And maybe they went a bit wacko which explains their odd behavior.

@Mijin

And yeah, I broadly agree, but this is a different point. As in, you were arguing about the size of UAPs, and I was listing reasons why “massive starship making slow voyage” cannot be assumed as the only way for aliens to get from star A to star B.
Now if you’re making the point that it’s strange we can see UAPs on radar, say, yet never record them leaving the atmosphere, then yes, I’d agree that’s strange. If the alien craft have any way to hide from radar, why do they ever turn it off?
But I don’t see what this point has to do with the size of the ships concerned.

Nothing. The climbing problem addresses the idea that there is a mothership.
Tiny probes might be a solution to the Fermi Paradox, though. There are alien artifacts buzzing around our system, but they are too small to see. And we might not be interesting enough to send real lifeforms.

[Voyager]

@Mijin

Meanwhile, it’s extremely unlikely we would encounter an alien species mere centuries ahead of us technologically; they are far more likely to be millions of years ahead (or behind).

Exactly. This is what bugs me about space opera - almost all the interesting aliens are close enough technologically to be interesting. That won’t happen. The space opera I’m writing has a solution to this problem.

[Mijin]

@Voyager

supposedly, is way bigger than this and would have to be deliberately sent.

Not necessarily.
To us, the energy difference between accelerating something the size of a rice grain to relativistic speeds versus something, say, the size of a garden shed is absolutely critical, as we’re still mostly barbecuing fossils for our energy needs. No reason to assume that a species millions of years ahead of us, that by definition is interstellar (so would have access to energy sources many orders of magnitude greater than anything we could do on earth, save crushing the earth into a black hole), would see things the same way.

Also, they could just build self-replicating probes, so N “big” probes would be deliberately launched but the one(s) arriving at Earth may have been their far descendents.

@Voyager

Nothing. The climbing problem addresses the idea that there is a mothership.

No, the climbing problem is addressing the problem at a whole other level.
You can’t say “The UAPs, if they were alien craft, must have come directly as they are, because if there was a mothership, why don’t we see the UAPs exit the atmosphere?” because even if the craft came to earth directly they’d also have to exit our atmosphere.
So it’s just an argument against the UAPs being extraterrestrial, period. Which is fine, but I don’t know why you’re mischaractizing it.

@Voyager

And we might not be interesting enough to send real lifeforms.

That gives me an idea for a story too.
How about aliens find us so uninteresting, and so little threat to them, that their probes just come in a very overt way – all of humanity can be of no doubt we’ve been visited by aliens – but they just take a look around and fly away. We have no way to stop them, or know where they went, and they ignore our attempts at communications.
It would be bleak, but it’s plausible, and I don’t think it’s been done much in sci fi.

[eburacum_45]

I would caution against accelerating grains of rice to relativistic speeds, by the way. The interstellar medium is dense enough to erode objects travelling at high speeds; a grain of rice would disappear in less than a light year at anything more than a few percent of c.

At speeds fast enough to allow noticeable time dilation, the entire ship would vapourise unless it were carefully shielded. There are many problems associated with interstellar travel, most of which have solutions, but none of those solutions are particularly convenient.

[Mijin]

@eburacum_45

I would caution against accelerating grains of rice to relativistic speeds, by the way. The interstellar medium is dense enough to erode objects travelling at high speeds; a grain of rice would disappear in less than a light year at anything more than a few percent of c.

Interesting.
The thing with Starshot was not in suggesting it’s something humans can already do. Even the guys behind Starshot concede that there are a number of significant challenges still to be solved.

It was just in the context of trying to constrain what kind of probe a millions-of-years of spacefaring civilization would be capable of constructing, crucially what is the minimum size. I think it’s relevant that humans – whose whole space endeavors still amount to less than one human lifetime, and you only need to go back a couple centuries for a horse to be our fastest transportation technology – are contemplating making gram-sized craft.

[eburacum_45]

Breakthough:Starshot is interesting. They have identified many problems, and suggested solutions.

By coincidence, I recently asked Avi Loeb a question about 'Oamoamoa, in a Q&A session; if this unusual object is typical of interstellar debris in our stellar vicinity, he suggests that we might expect to see many more with similar qualities. Perhaps quadrillions of them, if they are distributed randomly.

Considered as an interstellar messenger, 'Oamuamua is interesting; probably very flat and thin, it resembles a lightsail. However its speed is very slow, almost stationary with respect to the local galaxy. Not a strategy I’d recommend for anyone in a hurry.

[Voyager]

@Mijin

To us, the energy difference between accelerating something the size of a rice grain to relativistic speeds versus something, say, the size of a garden shed is absolutely critical, as we’re still mostly barbecuing fossils for our energy needs. No reason to assume that a species millions of years ahead of us, that by definition is interstellar (so would have access to energy sources many orders of magnitude greater than anything we could do on earth, save crushing the earth into a black hole), would see things the same way.

Also, they could just build self-replicating probes, so N “big” probes would be deliberately launched but the one(s) arriving at Earth may have been their far descendents.

We could compute how much antimatter, with perfectly efficient conversion to energy, they’d need. I can see a fixed power plant used to accelerate the probes, but you need to decelerate to buzz around a planet.
And self-replicating probes passing through the solar system is perfectly plausible. I haven’t been arguing against them at all.

@Mijin

You can’t say “The UAPs, if they were alien craft, must have come directly as they are, because if there was a mothership, why don’t we see the UAPs exit the atmosphere?” because even if the craft came to earth directly they’d also have to exit our atmosphere.

Why would they need to leave? There are plenty of place to hide on earth. More efficient also.
That no one sees these things approaching is another argument for them being something besides objects.

@Mijin

How about aliens find us so uninteresting, and so little threat to them, that their probes just come in a very overt way – all of humanity can be of no doubt we’ve been visited by aliens – but they just take a look around and fly away. We have no way to stop them, or know where they went, and they ignore our attempts at communications.
It would be bleak, but it’s plausible, and I don’t think it’s been done much in sci fi.

Sounds like Rendezvous with Rama. The original one, not the Gentry Lee travesties.

[Mijin]

@Voyager

We could compute how much antimatter, with perfectly efficient conversion to energy, they’d need. I can see a fixed power plant used to accelerate the probes, but you need to decelerate to buzz around a planet.

Right, and that amount will be relative to the mass of the ship. So I still don’t see how this is an argument suggesting the ships must be any particular size.

So, even assuming first of all that they need to use antimatter-matter annihilation as propulsion, we would need to tag on additional assumptions (e.g. that antimatter can only be contained by magnetic fields, as humans currently do, that powerful magnetic fields need big coils to generate them etc etc) to make this an argument for ship size. But once again, given that we’re talking about millions of years of technology here, none of this is going to be very compelling.

@Voyager

Why would they need to leave? There are plenty of place to hide on earth.

Sure, but again, this isn’t really an argument against motherships though, as if we’re comfortable supposing ships might come here and hide, we could just say that the mothership launches ships that come here and hide.

@Voyager

That no one sees these things approaching is another argument for them being something besides objects.

Yeah, but as I say, only in the sense that hiding one minute, then revealing themselves the next is inconsistent behaviour. I have no issue in the abstract with aliens being able to enter our atmosphere without being seen, if that’s what they wanted to do.

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The topic of aliens puts me in an uncomfortable place generally. Normally, I don’t like “What the bleep do we know?” style arguments, which are largely based on ignorance. We already understand a great deal about our universe; you don’t need to physically visit stars to be able to make very accurate predictions and inferences about them.

However, hyper-advanced life is a wild card here. The difference between us and them would likely vastly dwarf the difference between us and cave men. While they cannot do anything physically impossible of course, it’s likely that at least some things which we think of as physically impossible may be more nuanced to such a species.

Let alone engineering problems. Anything that looks merely impractical or technically difficult or whatever to us, would almost certainly belong to their set of trivial problems. Their difficult problems will be ones we don’t even know about yet.

[Voyager]

@Mijin

So, even assuming first of all that they need to use antimatter-matter annihilation as propulsion, we would need to tag on additional assumptions (e.g. that antimatter can only be contained by magnetic fields, as humans currently do, that powerful magnetic fields need big coils to generate them etc etc) to make this an argument for ship size. But once again, given that we’re talking about millions of years of technology here, none of this is going to be very compelling.

Millions of years old civilizations with hyper-advanced technologies which have made no impact on the galaxy?
For story purposes I can, and have, invented technologies which make UAPs feasible. I think I’d have a hard time explaining why they behave like they do. But until Doc Brown shows me a Mr. Antimatter, I’m going to be dubious about it in the real world.

@Mijin

However, hyper-advanced life is a wild card here. The difference between us and them would likely vastly dwarf the difference between us and cave men. While they cannot do anything physically impossible of course, it’s likely that at least some things which we think of as physically impossible may be more nuanced to such a species.

Well, the Star Trek solution seems to be that all highly advanced species stick to their home worlds (or home dimensions) except for weirdos like Q.
Civilizations which survive a million years aren’t going to be like us except for cooler toys.They’ll be immortal for sure. Who can tell what else? Lucy probably didn’t have any thoughts about whether she was an influencer.

[Darren_Garrison]

@Darren_Garrison

Those are Tel’taks.

And now here comes the Ha’tak.

Asteroid the size of the Great Pyramid of Giza to fly (safely) by Earth Sunday

[AlienBabble]

Tomorrow, at 9am EST, a House subcommittee for intelligence will hold public hearings on the issue of unidentified aerial phenomena, aka: Chinese and Russian drones, lens flares, seagulls, radar malfunctions, jet engines, and other, all-encompassing (mis)identifications. A link is provided below for your convenience.

Open C3 Subcommittee Hearing on Unidentified Aerial Phenomena

[Just_Asking_Questions]

@AlienBabble

seagulls, …A link is provided below for your convenience.

"SEAGULLS! (Stop It Now)" -- A Bad Lip Reading of The Empire Strikes Back

[AlienBabble]

Bipartisan Measure Aims to Force Release of U.F.O. Records

[DrDeth]

Okay, let us postulate aliens. Then we assume they are hiding.

They why would they have lights on their craft?

This answers most UFO sightings.