Do you think any aliens exist in the universe?

[Loren Pechtel]

...
The problem I see is that there are a lot of assumptions being made about living in such an environment, most based on assuming that it would be just like gravity. I haven't seen anyone addressing how the human body would react. Our sense of balance and orientation has evolved under the influence of gravity primarily by the inner ear sensing 'down'. In a gravity well, that is sensed by the location of the liquid in the inner ear reacting to the radial force of gravity. In a rotating habitat, there will also be a tangential 'force' on that liquid. While our sight would inform us that 'down' was along a radial line, our sense of balance would tell us 'down' would be dependent on which direction we face. The O'Neill cylinder would be a very different environment than humans evolved in. It is easy to assume how well humans could function there but we really can't know until after a lot of testing is done. As an example; we assumed what living in zero-g would be like but were surprised to find that it caused skeletal deterioration and other effects.

No. Both your vision and your ear will say gravity is towards your feet. The cylinder needs to be big enough that your whole body experiences pretty much the same "gravity" and spinning slow enough (which it inherently will be if big enough) that you don't get some nasty gyroscopic effects from turning your head. What direction you are facing will have no effect on the "gravity".

It is easy to assume things, quite another to test the assumptions. Trying to walk in a rotating reference frame will result in a 'force' perpendicular to the direction someone is trying to walk that would be the cross product of motion and the rotational velocity. The question is the magnitude and how much that would disorient someone trying to walk. Or how fast could they walk without their sense of balance screaming at them that they are falling over.

You are picturing walking on a spinning disk. You would have confusion if you did so. Note that we are talking about cylinders--you're walking on the outer surface, not the end caps. (Now, if you were to try walking on the cylinder on Earth you would have a problem due to gravity.)

 

[skepticalbip]

...
The problem I see is that there are a lot of assumptions being made about living in such an environment, most based on assuming that it would be just like gravity. I haven't seen anyone addressing how the human body would react. Our sense of balance and orientation has evolved under the influence of gravity primarily by the inner ear sensing 'down'. In a gravity well, that is sensed by the location of the liquid in the inner ear reacting to the radial force of gravity. In a rotating habitat, there will also be a tangential 'force' on that liquid. While our sight would inform us that 'down' was along a radial line, our sense of balance would tell us 'down' would be dependent on which direction we face. The O'Neill cylinder would be a very different environment than humans evolved in. It is easy to assume how well humans could function there but we really can't know until after a lot of testing is done. As an example; we assumed what living in zero-g would be like but were surprised to find that it caused skeletal deterioration and other effects.

No. Both your vision and your ear will say gravity is towards your feet. The cylinder needs to be big enough that your whole body experiences pretty much the same "gravity" and spinning slow enough (which it inherently will be if big enough) that you don't get some nasty gyroscopic effects from turning your head. What direction you are facing will have no effect on the "gravity".

It is easy to assume things, quite another to test the assumptions. Trying to walk in a rotating reference frame will result in a 'force' perpendicular to the direction someone is trying to walk that would be the cross product of motion and the rotational velocity. The question is the magnitude and how much that would disorient someone trying to walk. Or how fast could they walk without their sense of balance screaming at them that they are falling over.

You are picturing walking on a spinning disk. You would have confusion if you did so. Note that we are talking about cylinders--you're walking on the outer surface, not the end caps. (Now, if you were to try walking on the cylinder on Earth you would have a problem due to gravity.)

Actually I am picturing walking on the inside wall of a spinning barrel. To imagine the 'forces' assume someone is walking along the inner wall of a spinning barrel and steps through a hole, they wouldn't fly away radially as they should if it was 'just like gravity' but tangentially to the barrel, perpendicular to what would be expected by someone thinking of it as gravity.

ETA; Thinking about it, the effects should be the same as your example of walking on a rotating disc but with two of the three axis interchanged.

 

[Jarhyn]

...
The problem I see is that there are a lot of assumptions being made about living in such an environment, most based on assuming that it would be just like gravity. I haven't seen anyone addressing how the human body would react. Our sense of balance and orientation has evolved under the influence of gravity primarily by the inner ear sensing 'down'. In a gravity well, that is sensed by the location of the liquid in the inner ear reacting to the radial force of gravity. In a rotating habitat, there will also be a tangential 'force' on that liquid. While our sight would inform us that 'down' was along a radial line, our sense of balance would tell us 'down' would be dependent on which direction we face. The O'Neill cylinder would be a very different environment than humans evolved in. It is easy to assume how well humans could function there but we really can't know until after a lot of testing is done. As an example; we assumed what living in zero-g would be like but were surprised to find that it caused skeletal deterioration and other effects.

No. Both your vision and your ear will say gravity is towards your feet. The cylinder needs to be big enough that your whole body experiences pretty much the same "gravity" and spinning slow enough (which it inherently will be if big enough) that you don't get some nasty gyroscopic effects from turning your head. What direction you are facing will have no effect on the "gravity".

It is easy to assume things, quite another to test the assumptions. Trying to walk in a rotating reference frame will result in a 'force' perpendicular to the direction someone is trying to walk that would be the cross product of motion and the rotational velocity. The question is the magnitude and how much that would disorient someone trying to walk. Or how fast could they walk without their sense of balance screaming at them that they are falling over.

You are picturing walking on a spinning disk. You would have confusion if you did so. Note that we are talking about cylinders--you're walking on the outer surface, not the end caps. (Now, if you were to try walking on the cylinder on Earth you would have a problem due to gravity.)

Actually I am picturing walking on the inside wall of a spinning barrel. To imagine the 'forces' assume someone is walking along the inner wall of a spinning barrel and steps through a hole, they wouldn't fly away radially as they should if it was 'just like gravity' but tangentially to the barrel.

See also why slung stones travel tangentially from the release.

 

[Loren Pechtel]

Actually I am picturing walking on the inside wall of a spinning barrel. To imagine the 'forces' assume someone is walking along the inner wall of a spinning barrel and steps through a hole, they wouldn't fly away radially as they should if it was 'just like gravity' but tangentially to the barrel, perpendicular to what would be expected by someone thinking of it as gravity.

ETA; Thinking about it, the effects should be the same as your example of walking on a rotating disc but with two of the three axis interchanged.

There's no contradiction here.

The person standing in the cylinder is moving tangential to the surface of the cylinder and would continue to move in that direction if they fell through. However, as the cylinder rotates the spot they are standing on will move in a vertical direction. Remember, Einstein said that you can't tell the difference between the elevator sitting on Earth and the elevator being accelerated while in space. Same thing here--the floor is always accelerating upwards, this feels the same as gravity pulling you downwards. With spin gravity you get second-order effects from the rotation but so long as the spinning section is large enough these become unimportant at the scale of the human body. (They do, however, remain important for sports involving sending objects on long trajectories. I realize there will also be some effects on handegg but nowhere near the effect of the sports that use extensions to increase the launch velocity. You can't really make one big enough to avoid this--material strength requirements go up linearly with radius and the atmospheric gradient will be steeper than on Earth--my calculus is too rusty to figure it out correctly but even a 4 mile diameter with a normal gravity gradient would put the hub out of OSHA spec and my gut says that with spin gravity an unacclimated person couldn't go to the hub at all.)

 

[Loren Pechtel]

See also why slung stones travel tangentially from the release.

But note the slinger feels the force radially, not tangentially.

 

[skepticalbip]

Actually I am picturing walking on the inside wall of a spinning barrel. To imagine the 'forces' assume someone is walking along the inner wall of a spinning barrel and steps through a hole, they wouldn't fly away radially as they should if it was 'just like gravity' but tangentially to the barrel, perpendicular to what would be expected by someone thinking of it as gravity.

ETA; Thinking about it, the effects should be the same as your example of walking on a rotating disc but with two of the three axis interchanged.

There's no contradiction here.

The person standing in the cylinder is moving tangential to the surface of the cylinder and would continue to move in that direction if they fell through.

Exactly. And the liquid in the inner ear tries to move tangential to the surface so will be forced away from its normal position under gravity.

However, as the cylinder rotates the spot they are standing on will move in a vertical direction. Remember, Einstein said that you can't tell the difference between the elevator sitting on Earth and the elevator being accelerated while in space.

You misunderstand Einstein's thought experiment. The accelerating elevator he described as the same as gravity was undergoing linear acceleration. He clearly explained that angular acceleration could easily be detected... because the effects I described are easily measured.

Same thing here--the floor is always accelerating upwards, this feels the same as gravity pulling you downwards. With spin gravity you get second-order effects from the rotation but so long as the spinning section is large enough these become unimportant at the scale of the human body.

That was my question. The magnitude of the difference or how fast someone tries to walk without the disorientation.

(They do, however, remain important for sports involving sending objects on long trajectories. I realize there will also be some effects on handegg but nowhere near the effect of the sports that use extensions to increase the launch velocity. You can't really make one big enough to avoid this--material strength requirements go up linearly with radius and the atmospheric gradient will be steeper than on Earth--my calculus is too rusty to figure it out correctly but even a 4 mile diameter with a normal gravity gradient would put the hub out of OSHA spec and my gut says that with spin gravity an unacclimated person couldn't go to the hub at all.)

Again, we can not really know how well people would be able to function in such a different environment than they evolved in without testing. And even with a large diameter habitat there will be major differences.

 

[Jarhyn]

Actually I am picturing walking on the inside wall of a spinning barrel. To imagine the 'forces' assume someone is walking along the inner wall of a spinning barrel and steps through a hole, they wouldn't fly away radially as they should if it was 'just like gravity' but tangentially to the barrel, perpendicular to what would be expected by someone thinking of it as gravity.

ETA; Thinking about it, the effects should be the same as your example of walking on a rotating disc but with two of the three axis interchanged.

There's no contradiction here.

The person standing in the cylinder is moving tangential to the surface of the cylinder and would continue to move in that direction if they fell through.

Exactly. And the liquid in the inner ear tries to move tangential to the surface so will be forced away from its normal position under gravity.

However, as the cylinder rotates the spot they are standing on will move in a vertical direction. Remember, Einstein said that you can't tell the difference between the elevator sitting on Earth and the elevator being accelerated while in space.

You misunderstand Einstein's explanation. The accelerating elevator he described as the same as gravity was undergoing linear acceleration. He clearly explained that angular acceleration could easily be detected... because the effects I described are easily measured.

Same thing here--the floor is always accelerating upwards, this feels the same as gravity pulling you downwards. With spin gravity you get second-order effects from the rotation but so long as the spinning section is large enough these become unimportant at the scale of the human body.

That was my question. The magnitude of the difference or how fast someone tries to walk without the disorientation.

(They do, however, remain important for sports involving sending objects on long trajectories. I realize there will also be some effects on handegg but nowhere near the effect of the sports that use extensions to increase the launch velocity. You can't really make one big enough to avoid this--material strength requirements go up linearly with radius and the atmospheric gradient will be steeper than on Earth--my calculus is too rusty to figure it out correctly but even a 4 mile diameter with a normal gravity gradient would put the hub out of OSHA spec and my gut says that with spin gravity an unacclimated person couldn't go to the hub at all.)

Again, we can not really know how well people would be able to function in such a different environment than they evolved in without testing. And even with a large diameter habitat there will be major differences.

To be fair, both humans and AI can perform a frightful array of things they never evolved with distinct pressure towards, mostly on account of it being co-adaptive to environments we do find ourselves in.

For example wearing a pair of "glasses" that reverses and flips our vision.

After a while of that, we just... Understand how to translate that away.

We do so many such perceptual translations so seemlessly that it's a little much to claim we could not adapt our function to such.

 

[excreationist]

To be fair, both humans and AI can perform a frightful array of things they never evolved with distinct pressure towards, mostly on account of it being co-adaptive to environments we do find ourselves in.

For example wearing a pair of "glasses" that reverses and flips our vision.

After a while of that, we just... Understand how to translate that away.

I've actually got a pair myself....

Upside down goggles - Wikipedia

en.wikipedia.org

Experiments show we quickly adjust to seeing everything upside-down

A researcher wearing goggles that inverted everything stumbled about wildly at first, but soon enough he was able to ride a bicycle

www.theguardian.com

After 10 days, he had grown so accustomed to the invariably upside-down world that, paradoxically and happily, everything seemed to him normal, rightside-up. Kohler could do everyday activities in public perfectly well: walk along a crowded sidewalk, even ride a bicycle

 

[Loren Pechtel]

Again, we can not really know how well people would be able to function in such a different environment than they evolved in without testing. And even with a large diameter habitat there will be major differences.

What I'm talking about with size is the air pressure going down with altitude.

 

[Loren Pechtel]

To be fair, both humans and AI can perform a frightful array of things they never evolved with distinct pressure towards, mostly on account of it being co-adaptive to environments we do find ourselves in.

For example wearing a pair of "glasses" that reverses and flips our vision.

After a while of that, we just... Understand how to translate that away.

I've actually got a pair myself....

Upside down goggles - Wikipedia

en.wikipedia.org

Experiments show we quickly adjust to seeing everything upside-down

A researcher wearing goggles that inverted everything stumbled about wildly at first, but soon enough he was able to ride a bicycle

www.theguardian.com

After 10 days, he had grown so accustomed to the invariably upside-down world that, paradoxically and happily, everything seemed to him normal, rightside-up. Kohler could do everyday activities in public perfectly well: walk along a crowded sidewalk, even ride a bicycle

I believe the same thing happens with right-left inverters.

 

[GenesisNemesis]

Probably, but I also think that because the Universe tends to not conform to our expectations, there probably aren't hyper-intelligent beings out there. At least, not a lot of them.

 

[bilby]

Probably, but I also think that because the Universe tends to not conform to our expectations, there probably aren't hyper-intelligent beings out there. At least, not a lot of them.

Welcome back GN!

 

[Bomb#20]

Probably, but I also think that because the Universe tends to not conform to our expectations, there probably aren't hyper-intelligent beings out there. At least, not a lot of them.

Perhaps not, but a lot of hyper-intelligent beings out there seems rather more probable than exactly one.

 

[Swammerdami]

My own musings on the topic.

1. It's not hard to imagine H. sapiens developing the wherewithal to live in a space-ship for thousands of years. But being able to terraform a new world for permanent occupancy is much harder.

2. There may be no short-cut (hyperdrive, worm-hole) to improve on subliminal travel.

3. If sufficiently motivated and able to survive on a home world, we can imagine a civilization able to explore (at subliminal speeds) the galaxy, select targets for terraforming, maintain zoos of other lifeforms encountered, and so on. A fleet of mother-ships and lesser vehicles would inhabit the galaxy. It is possible that the species that originally conceived of this fleet is no longer existent, or unable to travel, but is replaced with one or more artificial (or encountered) life forms.

If average mother-ship replication rate is 8000 years, the fleet could grow a thousand-fold in 8 million years. Sustaining that replication rate might require exploiting many planets. There could then be as many mother-ships as stars in the Milky Way after 35 million years. Some ships might be directed at neighboring galaxies, but — unlike for useful intragalaxy signaling — communication with extragalactic probings would be lost.

4. How likely is it that a planet will develop life as advanced as, say, H. sapiens? This is not an easy question.

5. Many scientists guess that no complex life is impossible in our universe without the familiar C-N-O-H biochemistry. Sure there might be variations: Could a backbone other than phosphates provide the necessary structure for a reliable genome? There's a good paper on-line which lists alternatives, explains the utility of the phosphate backbone and so on. I'll track down the URL if there's interest. (Another worth-reading paper is Schrodinger's What is Life?)

Is it not widely guessed that our Universe is one of many, ours having a particular Fine Structure Constant for example, while different universes have different FSCs? In the sequel we keep the FSC fixed at its observed value. Only a biochemistry as observed on Earth is plausible.

6. Nick Lane goes further and thinks that the submarine alkaline trickling vents are the only plausible way for life to originate!

7. From a clumsy reaction chamber — or more likely many chambers in contact — LUCA emerged on Earth, the common ancestor of Bacteria and Archaeotes. LUCA is a splendid life-form, with (a) a large number of enzymes and ribo-enzymes implementing the genetic code, and (b) three proteins which form a proton-driven ATP synthesizer. (We just mention the two "most impressive"; LUCA also had sodium anti-porters and FeS enzymes.) What are the odds that such an intricate and successful Goldilocks-like LUCA would evolve? I don't think there's an authoritative statistical analysis.

Note that Nick Lane prefers ATP synthase (the 3-protein complex with a rotating part) as a paragon over DNA. One rotation ports ten protons across the membrane (through the rotator) and assembles three ATP molecules from the ADP+P raw materials. The total mass of all ATP one of us produces (NOT subtracting its ADP residue) exceeds within SECONDS (or some preposterous such) the total mass of the human body.

So what is the chance that the early interactions will evolve into a cell as complex as LUCA? Astronomically against? Or inevitable? I dunno.

8. There is much other impressive evolution besides the ribosome/genetic code and ATP synthase. Especially impressive is the giant gulf from prokaryotes to sexual eukaryotes. The gulf from the simplest eukaryote to H. sapiens may be small in comparison. Odds against or inevitable? I dunno.

9. So what is the answer, the output of the Bayes Equation? As I said in one of the Jesus threads, prior odds may be too hard to come by to be confident of any claim. If someone says 10⁶ is probably not sufficient planets to expect finding advanced life, but 10¹⁰ is, I'd question their objectivity.

10. One (very weird?) conjecture is that evolution may follow a goal-seeking path (cf, Bernstein–Vazirani algorithm or Shor's algorithm or even tunnelling electrons in cellular respiration and photosynthesis) The relationship between such well known instances of what I call "goal-seeking" and retrocausality is unclear.

And, whatever we think about points 1 - 10, if the odds of life anywhere in the universe are so low that Zero is far most likely, with One living planet the distant 2nd-most likely, then we KNOW the unlikely One is the case, not the Zero!

 

[Jarhyn]

@Swammerdami

As concerns other universes, be the discussion on extant parallels within some specific cosmology, or be the discussion of some concept of "universe" as in "free-standing system of mathematical deterministic function evolving from some initial state"...

As regards the latter, there are lots of other universes which may be implemented. Many don't rely on concepts of fine structure constants at all.

Rather, I think that the basis of what we ought be searching for is whether a system may come to model its own physical mathematics for the sake of preserving and growing the model.

It just really really helps when some sort of cellular automata is capable of reproducing and hosting that representation. Otherwise, there's not really much opportunity for growth.

 

[Swammerdami]

I don't think there's any doubt that mathematical systems and/or simulations and/or appropriately tuned physical systems can exist that will exhibit advanced life — our own Universe constitutes an existence proof.

But the usual way that OP's question or the Fermi Paradox is framed is based on OUR Universe with the specific physical laws WE endure.

 

[SIB]

To me, we would also have to define life. How would an engineer, chemist, physics, astrophysics, describe what is life. Is biology 101 the only definition? if that is the case then the earth's biosphere has more than half of the traits. All of them we think about what is reproduction and and only one set of dna really mean in terms of degrees of freedom.

The the questions shifts from "life" or "organism" to "alive" and/or "alive and aware of itself". Then on to separation of the various parts. For me any way.

 

[ramoss]

What I'm saying is partly based on what the richest man on the world is saying who runs related companies (SpaceX, the boring company, etc) - though I think it is a bad idea and they should just go to the moon instead....

Why do you think the fact that he’s the richest man in the world counts for anything?

He is good at large scale practical organisation. It seems in the near future he will be building the rockets that can hold 1000 passengers to go to Mars. I think that adds more weight to his views than if he was a futurist that was financially struggling. Also he could use a lot of his own money to help make this happen.

One thousand passengers to go to Mars to do what? Die there?

His money adds no weight to his views. He doesn’t know what he’s talking about. I expect, like Donald Trump, he just bilks rubes for money.

To locate a thousand people on Mars — much more so a million! — would require a vast, nay astronomical expenditure of funds to set up an infrastructure to support these people, a project of many generations if it is feasible at all. No one is going to pay for this bullshit. We don’t even have a moon base, and the last time humans walked on the moon was half a century ago! What we are going to be doing in the next century is not moving to Mars. It’s going to be striving desperately to save ourselves from the devastating impact of accelerating climate change.

He's good at making people think he is a better business man than he is.

 

[excreationist]

He's good at making people think he is a better business man than he is.

I think the problem is that he can convince some people that his plan to send 1 million people to Mars by 2050 is a good plan.

Elon Musk says he plans to send 1 million people to Mars by 2050 by launching 3 Starship rockets every day and creating 'a lot of jobs' on the red planet

Musk said he would send 1,000 Starships full of people into Earth orbit, then rocket them all to Mars during an opportune 30-day window.

www.businessinsider.com

I think being the richest man in the world at the age of 51 shows he is an excellent business man.... without inheriting billions from his parents....

 

[pood]

He's good at making people think he is a better business man than he is.

I think the problem is that he can convince some people that his plan to send 1 million people to Mars by 2050 is a good plan.

Sure, it’s a great plan if the plan is to waste a gob of money to consign a million people to their deaths.