"Nobody out there cares about us"

[TheVat]

@mistermack

Interesting variant on the rare Earth idea.  Or maybe I should say rare big brain on Earth idea.  It is a possible formulation of Frank Drake's equation, where N is zero because f_i is zero.  I too have given some thought to that f_i parameter and wondered if we tend to extrapolate badly from a single data point.  There could be planets, too, where intelligence arises, but confounding factors keep it from doing anything technologically.  Brilliant philosophizing parrots who can't do much with tools beyond poking sticks around.  Smart apelike creatures with a metal-poor environment who never do metallurgy.   And so on.  

[mistermack]

2 hours ago, TheVat said:

Brilliant philosophizing parrots who can't do much with tools beyond poking sticks around.  Smart apelike creatures with a metal-poor environment who never do metallurgy.   And so on.

The freakishness of our species doesn't begin and end with the big brain, either. It doesn't feel freakish to us, but walking on two legs was an incredibly unlikely adaptation. Take away birds, which are a special case with the wings, and there's nothing on Earth like us. And it was the change to habitual bipedalism that led directly to evolving the big brain. The fossils show that we first became upright, and then started the brain expansion. So you have not one freakish development, but two, and without one or the other, we would just be still apes in Africa, rooting around for our next meal. 

And of course, you have to multiply the odds against either happening together, to get an idea of just how unlikely our path to a technological civilization really was. 

[CharonY]

Bipedalism is not that uniques. There are bipedal dinosaurs, and their descendants. It is rare among mammals, though some at least can be transiently bipedal. From there having few species (including humans) specializing in locomotion using their hind legs is not that unique. One of the rarer qualities is probably the lack of a tail as counterbalance.

With regard to brain size, it is not that great of an indicator, as in total size, we are eclipsed by many larger animals and using brain to body ratios typically favours smaller species. In neither measure are we on top of the rankings.

[Alex_Krycek]

I think Greene's argument is logical.  His argument kind of reminds me of my old boss, who was incredibly excited about his new BMW.  He even had employees take a special break so they could come out and look at it.  Nobody thought his car was special except him.  

Edited June 12, 2022 by Alex_Krycek

[mistermack]

14 hours ago, TheVat said:

Smart apelike creatures with a metal-poor environment who never do metallurgy.   And so on.

That actually raises another question. How could a water-living intelligent creature ever work with metals or plastics in the way that we can? It pretty much excludes planets or moons that have full covering of water or ice from ever doing technology, as least in the way that we have done it. If you can't work metals or plastics you might as well not even start. Imagine there was no land, but in the water, there were super-intelligent dolphins, far brainier than us. How do they go about making a transmitter? Or even just a tv or a vacuum cleaner?

[dimreepr]

20 minutes ago, mistermack said:

That actually raises another question. How could a water-living intelligent creature ever work with metals or plastics in the way that we can? It pretty much excludes planets or moons that have full covering of water or ice from ever doing technology, as least in the way that we have done it. If you can't work metals or plastics you might as well not even start. Imagine there was no land, but in the water, there were super-intelligent dolphins, far brainier than us. How do they go about making a transmitter? Or even just a tv or a vacuum cleaner?

Why do they need a transmiter, a tv or a vacuum cleaner (Is a better question)?

 

[mistermack]

18 minutes ago, dimreepr said:

Why do they need a transmiter, a tv or a vacuum cleaner (Is a better question)?

Exactly the same reason we do.

To keep up with the neighbours.

[dimreepr]

7 minutes ago, mistermack said:

Exactly the same reason we do.

To keep up with the neighbours.

Then we differ in our definition of need...

[swansont]

16 hours ago, TheVat said:

Smart apelike creatures with a metal-poor environment who never do metallurgy

Which you’d expect early in the universe, before you had stars going supernova or having neutron stars merging, and dispersing the heavier elements.

You’d also have issues if they evolved early in the planet’s life, before large coal and oil deposits formed.

[Airbrush]

On 6/10/2022 at 4:07 AM, swansont said:

I agree with Greene to some extent; the earth would not stand out. If they are more than ~100 LY away, what would make us “interesting”?

It’s not communicating with an anthill so much as communicating with a rock. Why would they care about this rock?

Maybe they can determine idyllic habitable zones in the galaxy where any possible life would have a high probability to thrive and evolve for a long time and evolve intelligence.  They know how fitful red dwarf stars are, so they may only look at sunlike stars and look for gases in planet atmospheres to reveal what stage of evolution life is in.  They could have methods of surveying the galaxy we can't imagine.

Edited June 12, 2022 by Airbrush

[swansont]

5 minutes ago, Airbrush said:

Maybe they can determine idyllic habitable zones in the galaxy where any possible life would have a high probability to thrive and evolve for a long time and evolve intelligence.  They know how fitful red dwarf stars are, so they may only look at sunlike stars and look for gases in planet atmospheres to reveal what stage of evolution life is in.  They could have methods of surveying the galaxy we can't imagine.

It doesn’t matter what their technique is if the evidence of intelligent life hasn’t had time to reach them yet.

[Airbrush]

Brian Greene said "Nobody out there cares about us because we are so ill-developed, we are so young on the cosmic scene that there is nothing interesting to find here."

That is misleading.  It would be more correct for Greene to say "Nobody out there cares about us, because they don't know we are here."  He makes it sound like we are not advanced enough for them to be interested.  We are mere ants, boring.  No, it is because they don't know we are here.  They are beyond 100 LY from us, that is all.

Edited June 12, 2022 by Airbrush

[TheVat]

Or they're locked in an intense competition to have the best vacuum cleaner.  

Some aliens can be quite shallow, you know.

11 hours ago, swansont said:

Which you’d expect early in the universe, before you had stars going supernova or having neutron stars merging, and dispersing the heavier elements.

You’d also have issues if they evolved early in the planet’s life, before large coal and oil deposits formed.

You have raised maybe an interesting speculative topic - could a tech civilization grow that had only wood (or other surface plant materials) as a fuel?  I suppose if they could make it to glassmaking then they could stumble on solar furnaces and such, and then leapfrog over the dirty fuel era.  

 

[swansont]

8 hours ago, TheVat said:

You have raised maybe an interesting speculative topic - could a tech civilization grow that had only wood (or other surface plant materials) as a fuel?  I suppose if they could make it to glassmaking then they could stumble on solar furnaces and such, and then leapfrog over the dirty fuel era.

It's the amount of fuel available, which might limit the population (number and geographic spread) and the energy density, which would restrict travel and scope of industrialization. Scientific advancement relies on having people free to pursue science, which would happen slower if more manual labor was still required because you didn't have the same available machinery that high-energy-density fuels make available. 

A solar furnace isn't going to propel a train very effectively, for example. I'm also not sure how effective metallurgy is going to be with wood vs coal fires.

 

[Intoscience]

12 hours ago, Airbrush said:

Brian Greene said "Nobody out there cares about us because we are so ill-developed, we are so young on the cosmic scene that there is nothing interesting to find here."

That is misleading.  It would be more correct for Greene to say "Nobody out there cares about us, because they don't know we are here."  He makes it sound like we are not advanced enough for them to be interested.  We are mere ants, boring.  No, it is because they don't know we are here.  They are beyond 100 LY from us, that is all.

Or, maybe intelligent life is common and abundant, and we are at the bottom of the scale, and not much different than thousands of other "more" interesting intelligence.  

Something I have considered is whether aliens would recognise us as intelligence in the first place? We often talk about maybe we cannot detect aliens because we do not recognise any signature of what we assume to be looking for.  Maybe that works both ways?  

[swansont]

13 hours ago, Airbrush said:

Brian Greene said "Nobody out there cares about us because we are so ill-developed, we are so young on the cosmic scene that there is nothing interesting to find here."

That is misleading.  It would be more correct for Greene to say "Nobody out there cares about us, because they don't know we are here."  He makes it sound like we are not advanced enough for them to be interested.  We are mere ants, boring.  No, it is because they don't know we are here.  They are beyond 100 LY from us, that is all.

To some extent they are the same thing. We haven't been "advertising" ourselves until relatively recently, so not knowing we are here and us being ill-developed are almost the same thing.

The distinction would be whether they know about us (and don't care), or don't know about us. But why would they know about us?

[Airbrush]

On 6/13/2022 at 5:23 AM, swansont said:

.....But why would they know about us?

Suppose they were thousands or millions of years beyond our technology.  Maybe they have surveyed this region of the galaxy for thousands of years and they already know precisely where the best habitable zones are in this local.  They could send high-speed probes to all interesting, highly habitable solar systems, that report back to the home planet.  If they witnessed life evolving on many different planets, they might be able to anticipate that Earth of 10,000BC  was promising to evolve technological beings within a few thousand years.  Then they return thousands of years later when things get interesting.

Edited June 15, 2022 by Airbrush

[swansont]

9 hours ago, Airbrush said:

Suppose they were thousands or millions of years beyond our technology.  Maybe they have surveyed this region of the galaxy for thousands of years and they already know precisely where the best habitable zones are in this local.  They could send high-speed probes to all interesting, highly habitable solar systems, that report back to the home planet.  If they witnessed life evolving on many different planets, they might be able to anticipate that Earth of 10,000BC  was promising to evolve technological beings within a few thousand years.  Then they return thousands of years later when things get interesting.

What is “high speed”?

This is from StringJunky is the other active thread discussing interstellar travel

Quote

An example of the size of the task: Suppose we aim for Alpha Proxima, as it's 'only' 3.2LYRs away. Suppose we had a  rocket that could travel a million mph. It'll take us 19 200 000 years to get there..

IOW, your scenario does not jibe with the actual logistics. You can’t just hand-wave your way through this. Some actual analysis is required.

[Airbrush]

12 hours ago, swansont said:

....What is “high speed”?

"Using an array of laser thrusters, a probe weighing one gram would travel 4.4 light years, to the nearest star, Alpha Centauri, in just two decades. That’s only twice as long as it took the New Horizons spacecraft to fly by Pluto."

"Such probes would combine nanophotonics, a miniaturized radio thermal generator for 1 W of power, nanothrusters for attitude adjustment, thin-film supercapacitors for energy storage, and even a small camera.  Equipped with a laser sail just under one meter (3 ft) in diameter, such a spacecraft could be propelled by a 70 GW laser array to about 26 percent the speed of light in about 10 minutes and reach Alpha Centauri in only 15 years."

Reaching for the stars: How lasers could propel spacecraft to relativistic speeds (newatlas.com)

If we can do this in the not very distant future, what kind of masses could an ETI send at what kind of speeds if their technology was thousands or millions of years beyond ours?  They may have superior nanotechnology.

Edited June 16, 2022 by Airbrush

[StringJunky]

9 hours ago, Airbrush said:

"Using an array of laser thrusters, a probe weighing one gram would travel 4.4 light years, to the nearest star, Alpha Centauri, in just two decades. That’s only twice as long as it took the New Horizons spacecraft to fly by Pluto."

"Such probes would combine nanophotonics, a miniaturized radio thermal generator for 1 W of power, nanothrusters for attitude adjustment, thin-film supercapacitors for energy storage, and even a small camera.  Equipped with a laser sail just under one meter (3 ft) in diameter, such a spacecraft could be propelled by a 70 GW laser array to about 26 percent the speed of light in about 10 minutes and reach Alpha Centauri in only 15 years."

Reaching for the stars: How lasers could propel spacecraft to relativistic speeds (newatlas.com)

If we can do this in the not very distant future, what kind of masses could an ETI send at what kind of speeds if their technology was thousands or millions of years beyond ours?  They may have superior nanotechnology.

You've got interstellar space with a density of 1 atom/cm³ and intergalactic space at 1 atom/ metre³. How long will it last colliding with them at relativistic speeds? I would imagine if it collided with a mass in grams, or less, it would be toast.

Edited June 16, 2022 by StringJunky

[swansont]

10 hours ago, Airbrush said:

"Using an array of laser thrusters, a probe weighing one gram would travel 4.4 light years, to the nearest star, Alpha Centauri, in just two decades. That’s only twice as long as it took the New Horizons spacecraft to fly by Pluto."

"Such probes would combine nanophotonics, a miniaturized radio thermal generator for 1 W of power, nanothrusters for attitude adjustment, thin-film supercapacitors for energy storage, and even a small camera.  Equipped with a laser sail just under one meter (3 ft) in diameter, such a spacecraft could be propelled by a 70 GW laser array to about 26 percent the speed of light in about 10 minutes and reach Alpha Centauri in only 15 years."

Reaching for the stars: How lasers could propel spacecraft to relativistic speeds (newatlas.com)

If we can do this in the not very distant future, what kind of masses could an ETI send at what kind of speeds if their technology was thousands or millions of years beyond ours?  They may have superior nanotechnology.

No, we can't do this in the near future.

"Equipped with a laser sail just under one meter (3 ft) in diameter, such a spacecraft could be propelled by a 70 GW laser array to about 26 percent the speed of light in about 10 minutes"

There are a lot of unstated assumptions here. I'm guessing someone just looked at the force exerted, calculated the acceleration and that was the end of it.

Here is just one: what level of reflectivity does your solar sail have to achieve so it isn't vaporized by 70 GW of laser power?

Another: at ~0.25c, how long would your probe get to look at a solar system?

[Airbrush]

"Breakthrough Starshot is a research and engineering project by the Breakthrough Initiatives to develop a proof-of-concept fleet of light sail interstellar probes named Starchip,^[1] to be capable of making the journey to the Alpha Centauri star system 4.37 light-years away. It was founded in 2016 by Yuri Milner, Stephen Hawking, and Mark Zuckerberg.^[2][3]

"A flyby mission has been proposed to Proxima Centauri b, an Earth-sized exoplanet in the habitable zone of its host star, Proxima Centauri, in the Alpha Centauri system.^[4] At a speed between 15% and 20% of the speed of light,^[5][6][7][8] it would take between twenty and thirty years to complete the journey, and approximately four years for a return message from the starship to Earth.

"The project was announced on 12 April 2016 in an event held in New York City by physicist and venture capitalist Yuri Milner, together with cosmologist Stephen Hawking, who was serving as board member of the initiatives. Other board members include Meta Platforms (then known as Facebook, Inc.) CEO Mark Zuckerberg. The project has an initial funding of US$100 million to initialize research.  Milner places the final mission cost at $5–10 billion, and estimates the first craft could launch by around 2036...."

Breakthrough Starshot - Wikipedia

Solar sail - Wikipedia

Even Stephen Hawking was interested.  So you still think it is a fools' mission?  What is possible if aliens had another million years to develop better interstellar probes?

Here is an interesting interview with Brian Cox.  When asked about the probability of intelligent life in the universe he answered that he is only concerned about our galaxy.  I'm only interested in the probability of intelligent ETs within a few thousand light years.  Beyond that is irrelevant  It's way too far away to be of interest. 

Brian thinks intelligent aliens are so few and far between that there may be only one or two per galaxy.

 

Edited June 16, 2022 by Airbrush

[Ken Fabian]

How much interstellar exploration can a few grams do? What instruments can each carry? How about interstellar data transmissions? Even lots of them strung out as relays - receivers and transmitters and power source along the way needed in that case - I think not. Von Neumann machines look more likely to be successions of complexes of mining, refining, manufacturing machines than machines that can eat asteroid dirt and excrete copies of themselves - I think not. But tech that is thousands and millions of years ahead of us can overcome the obstacles suggests Time somehow erodes the laws of physics to allow magical technologies; we are closing in on a complete theory of everything and it doesn't look like it will support faster than light or time suspension or other magical shortcuts. I see science and tech development as S-curve not exponential or open ended.

To the Question - echoing some other comments, vast distances and the limits the laws of physics impose - the difficulties in detection or travel across them - stand out as the most obvious and likely reasons we haven't found any aliens and why aliens have not found us. Any suggestion that we are being deliberately left alone requires evidence they are within range but are avoiding us - we don't have any. I think there is nothing but baseless conjecture to think that; I think not.

[swansont]

1 hour ago, Airbrush said:

So you still think it is a fools' mission?

Absent technical analysis, I have lots of questions.  Nothing you’ve posted is a reasonable substitute for technical analysis.

From the wikipedia article

“The light sail is envisioned to be no larger than 4 by 4 meters (13 by 13 feet),^[1][50] possibly of composite graphene-based material.^{[1][33][6][36][43][51]} The material would have to be very thin and be able to reflect the laser beam while absorbing only a small fraction of the incident energy, or it will vaporize the sail.”

My objection, which is not addressed. The small fraction is very small. 

Also, the payload has to be on the dark side of the sail, or it, too, gets vaporized. I think that might introduce some stability issues. How do you keep the system from rotating/tumbling?

From one of the links (52) in the references

https://www.inverse.com/article/14352-the-starshot-breakthrough-light-beam-is-really-a-million-lasers-which-s-insane

“Eduardo Bendek, who has studied Alpha Centauri for nearly his whole career and is working on a proposal to send a space telescope out to study the region, thinks the biggest issue behind Starshot is to figure out how to avoid “vaporizing the spacecraft” with the light beam. The nanocraft are just a few grams in mass. There’s an extremely high likelihood that firing a 100-gigawatt laser at them would cause them to evaporate. Bendek cites a previous experiment at Lawrence Livermore National Laboratory that began a thermonuclear reaction using a laser with a fraction of that power. “I don’t know how they’re going to figure this out,” he says.”

[Ken Fabian]

On 6/11/2022 at 6:33 AM, MigL said:

What would be biological signatures that could be detected at astronomical distances ?
( don't answer right away if you need some sleep 🙂 )

Some thought has been put into what signatures we might look for - from one side of that question there are efforts like Sara Seager et al to build a comprehensive list of possible volatile compounds. The presence of chemicals that are not in thermodynamic equilibrium - some active process needed to sustain them - seems to be a major criteria, but a lot of chemicals made by life on Earth are unlikely to occur without life. Determining what can or is likely to occur without life is another aspect. What astronomy requires to detect them and how far out is another question. Planets crossing their parent stars visible from Earth and near space will only be a small fraction.

https://www.saraseager.com/wp-content/uploads/2020/07/Seager2016.pdf