Aliens from space (split from Time to talk about UFO's or now as the military calls them UAP's?)

[Moontanman]

Just now, swansont said:

What prompts you to think this? AFAICT detection of aliens has little to do with their motivations.

I didn't say it did, the only way we can know alien motivations is for us to ask them!

[swansont]

1 hour ago, Moontanman said:

I didn't say it did, the only way we can know alien motivations is for us to ask them!

Then I don’t understand your contention that anyone is assuming a Star Trek like scenario regarding motivation.

[MigL]

3 hours ago, Moontanman said:

Actually yes they are, the idea that aliens are just like us in the needs, wants, and desires department is exactly what Star Trek thinking is, the magical technology is just window dressing for what is essentially just a human story.

You're taking that a bit too far.
Aliens who are just like us, would require those things, but life, any kind of life, has some basic universal needs.
It would need an energy/food source and to reproduce; that is all.
Further, any life that emerged through an evolutionary process, would tend to optimize conditions to satisfy those needs.
Their motivations, and decision making, would be based accordingly, and I don't expect that to change, even for a civilization that has been around for billions of years.

But you are right. There is a slim possibility it could be ET aliens. Or time travelers, ghosts, fairies and leprechauns.
But when that trivial possibility is many orders of magnitude less likely than a 'hubcap thrown in the air', it's probably OK to discount it.

As to the technological obstacles to alien visitation, the Fermi Paradox/Drake Equation would have us inundated with alien civilizations, most of which should be much older than our relatively young one.
Yet none have made definitive contact. 
You would think at least one would have, even if others are just playing hide-and-seek with us.

Do you think maybe that means technological obstacles to interstellar travel are not easily dismissed ?
Or maybe they're too busy with concerns about energy/food sources and reproduction, to send Von Neumann probes to other star systems to gather information which they may never recover.

[zapatos]

I suppose it is also possible that life is manufactured by some advanced civilization. The manufactured beings may never reproduce except perhaps to manufacture a new one when an old one is lost. That way you could build in the capability up front to suspend biological processes for long voyages and add other features that would be beneficial for long voyages, without worrying about multiple generations or boredom.

[Moontanman]

1 hour ago, swansont said:

Then I don’t understand your contention that anyone is assuming a Star Trek like scenario regarding motivation.

My point is that when we assign human motivations to aliens we have no leg to stand on, in the Star Trek universe all or nearly all of the aliens are humanoid in both stature and motivations. 

1 hour ago, MigL said:

You're taking that a bit too far.
Aliens who are just like us, would require those things, but life, any kind of life, has some basic universal needs.
It would need an energy/food source and to reproduce; that is all.
Further, any life that emerged through an evolutionary process, would tend to optimize conditions to satisfy those needs.
Their motivations, and decision making, would be based accordingly, and I don't expect that to change, even for a civilization that has been around for billions of years.

I have to agree yet the devil is in the details. 

1 hour ago, MigL said:

But you are right. There is a slim possibility it could be ET aliens. Or time travelers, ghosts, fairies and leprechauns.
But when that trivial possibility is many orders of magnitude less likely than a 'hubcap thrown in the air', it's probably OK to discount it.

When your attitude is that all sighting are equally improbable you make a good point but this is simply not true. Not all sightings can be dismissed so easily, some cannot be dismissed at all. 

I few posts ago I posted a scientific paper about a UFO sightings but everyone has ignored it. This sighting is not so easily dismissed... still an unknown but obviously not a hubcap. 

1 hour ago, MigL said:

As to the technological obstacles to alien visitation, the Fermi Paradox/Drake Equation would have us inundated with alien civilizations, most of which should be much older than our relatively young one.
Yet none have made definitive contact. 
You would think at least one would have, even if others are just playing hide-and-seek with us.

The Fermi paradox and the Drake equation make some rather easily manipulated assumptions that can be used to predict almost any outcome. There could be reasons we are totally unaware of, from fear of bio contamination to simple laws a space fairing civilization might have about first contact. There is really no way to assert any reason over another. 

1 hour ago, MigL said:

Do you think maybe that means technological obstacles to interstellar travel are not easily dismissed ?
Or maybe they're too busy with concerns about energy/food sources and reproduction, to send Von Neumann probes to other star systems to gather information which they may never recover.

I think that if controlled hydrogen fusion is possible all those other concerns become moot. IN fact I think a pretty good argument can be made that any space fairing civilization would avoid planets and favor space habitats over colonising planets. This could led to the entire galaxy being inhabited by Von Neumann Probes colonising the galaxy via going to a star system and utilizing the asteroids and comets like bodies to build and maintain space habitats. This would also make star travel unnecessary as long as you had a star with debris around it like our Sun. We could realistically use the idea of rotating space habitats to build colonies that would when assed up amount to many times as much space as the surface of the earth. 

There are so many possibilities that do not limit an intelligence to just one planet but one thing you keep asserting bothers me a bit. You seem to think that Von Neumann Probes and the info they collect wouldn't be useful because ( I am assuming here) that the individual who sent the probe would be dead way before any data could be harvested from the probe. 

@TheVat explained why your take on this isn't as profound as you seem to think it s

  

 

41 minutes ago, zapatos said:

I suppose it is also possible that life is manufactured by some advanced civilization. The manufactured beings may never reproduce except perhaps to manufacture a new one when an old one is lost. That way you could build in the capability up front to suspend biological processes for long voyages and add other features that would be beneficial for long voyages, without worrying about multiple generations or boredom.

The possibilities of technology really do expand this discussion to new areas. 

[swansont]

2 hours ago, Moontanman said:

My point is that when we assign human motivations to aliens we have no leg to stand on, in the Star Trek universe all or nearly all of the aliens are humanoid in both stature and motivations. 

But who is doing this? Who is “we”?

The arguments against such travel are based on physics - e.g. travel is limited to slower - probably much slower - than c. It’s the alien proponents that are assigning motive - that humans and the earth are so fascinating that we keep being visited by them. 

2 hours ago, Moontanman said:

I few posts ago I posted a scientific paper about a UFO sightings but everyone has ignored it. This sighting is not so easily dismissed... still an unknown but obviously not a hubcap. 

It was not a scientific paper, and the conclusion was…what? They detected something that could not be identified. That’s not dismissing anything. It’s acknowledging that there’s not enough information to draw a definite conclusion. 

[Moontanman]

14 minutes ago, swansont said:

But who is doing this? Who is “we”?

The arguments against such travel are based on physics - e.g. travel is limited to slower - probably much slower - than c. It’s the alien proponents that are assigning motive - that humans and the earth are so fascinating that we keep being visited by them. 

Humans are the we, our society assigns motivations and emotions to our perception of the world. 

The idea we would be interesting is indeed a human assessment, I have to admit I would visit an alien planet if I could and while it might be difficult for us to imagine, an advanced civilization might grant researchers who specialize in primitive cultures exclusive rights to study a new civilization. Such a study might take millenia and all the while we are being studied they do not officially contact us to prevent the study itself from influencing our behaviors as much as possible. They may share our desire to acquire knowledge and a small fraction of them study newly emerging civilizations. 
The reasons why they visit could be anything, indeed they could be reasons we couldn't understand, they are aliens btw. Hell there are humans who specialize in studying animal excrement... maybe that is why they anal probe so many 💩 

Trying to discern their motivations is secondary at best to figuring out if this is going on at all. There is no reason to debate the whys and hows until we know if its actually happening and we can't know that until we start seriously looking at the data we have instead f dismissing it because we just can't imagine how it could be possible. 

Traveling slower than c is no barrier to star travel, I honestly don't see why anyone would think that, if our own civilization wanted to star travel it is conceivable. I kinda doubt you'd find anyone who wanted to spend that much money to do it but that is a capitalist view point. Not all civilizations will necessarily be motivated by profit. 

Personally I think the best motivator would be desire for knowledge. That one thing has motivated humans to do some really dangerous crazy stuff.. like the Moon landing. 

[TheVat]

 The Von Neuman hypothesis strikes me as the most neutral in its assumptions: for whatever reason, advanced civs may send out self-replicating units in the millions (and thence to billions via replication) and they just blanket all star systems in the spectral range most hospitable to life.  Or not.  Other filters are possible.  We can't say what cost/benefit ratio is determined by a K2-plus civilization, or if anthropological fascination has anything to do with it, or what ethos they may have about contact, or if carbon-based life is seen as interesting...or just an old-fashioned and disgusting fetish that preceded the Glorious Uploading.  Or quaint, and as @Moontanman mentioned, a niche hobby for some tiny fraction that studies emerging sentience.  If aliens were machine intelligences, they could have some form of immortality that would open up motivations we can't conceive of, where shutting down for a ten thousand year journey would be routine.  Or a nice field trip for fourth graders.  

[swansont]

1 hour ago, Moontanman said:

Humans are the we, our society assigns motivations and emotions to our perception of the world. 

But we’re talking about scientific analysis, which tries to remove such extraneous baggage from discussion (unless you are studying that particular phenomenon)

1 hour ago, Moontanman said:

Traveling slower than c is no barrier to star travel, I honestly don't see why anyone would think that, if our own civilization wanted to star travel it is conceivable. I kinda doubt you'd find anyone who wanted to spend that much money to do it but that is a capitalist view point. Not all civilizations will necessarily be motivated by profit. 

Every time I have invited you to do a technical analysis of this you have declined. Which is unfortunate, because it would be interesting, but also means that this assertion is not based on actual science. Instead, it is (as some of my former students would say) a matter of pressing the “I believe” button. But one can’t pretend that this is science.

[Moontanman]

19 minutes ago, swansont said:

But we’re talking about scientific analysis, which tries to remove such extraneous baggage from discussion (unless you are studying that particular phenomenon)

On any subject but UFOs I would agree with you. 

19 minutes ago, swansont said:

Every time I have invited you to do a technical analysis of this you have declined. Which is unfortunate, because it would be interesting, but also means that this assertion is not based on actual science. Instead, it is (as some of my former students would say) a matter of pressing the “I believe” button. But one can’t pretend that this is science.

Let's do it!

[MigL]

3 hours ago, Moontanman said:

Let's do it!

I like indulging nice guys, Moon, so I'll start us off.

Consider a constant acceleration ship, say 1g, for the confort of the occupants.

"From the planetary frame of reference, the ship's speed will appear to be limited by the speed of light — it can approach the speed of light, but never reach it. If a ship is using 1 g constant acceleration, it will appear to get near the speed of light in about a year, and have traveled about half a light year in distance. For the middle of the journey the ship's speed will be roughly the speed of light, and it will slow down again to zero over a year at the end of the journey.
As a rule of thumb, for a constant acceleration at 1 g (Earth gravity), the journey time, as measured on Earth, will be the distance in light years to the destination, plus 1 year. This rule of thumb will give answers that are slightly shorter than the exact calculated answer, but reasonably accurate."

From     Space travel under constant acceleration - Wikipedia

We can then make other quick estimates to travel time

"From the frame of reference of those on the ship the acceleration will not change as the journey goes on. Instead the planetary reference frame will look more and more relativistic. This means that for voyagers on the ship the journey will appear to be much shorter than what planetary observers see.
At a constant acceleration of 1 g, a rocket could travel the diameter of our galaxy in about 12 years ship time, and about 113,000 years planetary time. If the last half of the trip involves deceleration at 1 g, the trip would take about 24 years. If the trip is merely to the nearest star, with deceleration the last half of the way, it would take 3.6 years."

Now you might say"That's not too bad.". Only 113 000years pass on their home world to send a ship 100 000 light years. And a relatively short time to send it to a nearby star.
Even doubling that time for two-way journey seems reasonable.

Now comes the hard part.
( and I'm not going to attempt to quickly find/perform the calculation; I'll leave it to better, more fastidious, minds than mine )
How much Hydrogen do you need to carry, or collect along the way, in order to sustain a fusion reaction capable of sustaining a constant 1g acceleration/deceleration ?

Edited May 4 by MigL

[dimreepr]

11 hours ago, Moontanman said:

12 hours ago, swansont said:

Every time I have invited you to do a technical analysis of this you have declined. Which is unfortunate, because it would be interesting, but also means that this assertion is not based on actual science. Instead, it is (as some of my former students would say) a matter of pressing the “I believe” button. But one can’t pretend that this is science.

Let's do it!

Do what?

All you've got ATM is, my bible is better than your scientific knowledge; I didn't think you liked that approach...

 

13 hours ago, Moontanman said:

Humans are the we, our society assigns motivations and emotions to our perception of the world. 

Indeed.

"God/alien's is the blanket we use to cover the unknowns and give it a shape." I think this was a quote from a roadie for the "Rolling Stones".

[swansont]

9 hours ago, MigL said:

Now comes the hard part.
( and I'm not going to attempt to quickly find/perform the calculation; I'll leave it to better, more fastidious, minds than mine )
How much Hydrogen do you need to carry, or collect along the way, in order to sustain a fusion reaction capable of sustaining a constant 1g acceleration/deceleration ?

Also, how much reaction mass do you need to carry? What is the payload?

(At some point we get into the issue of how a craft survives hitting objects traveling near c)

[dimreepr]

28 minutes ago, swansont said:

(At some point we get into the issue of how a craft survives hitting objects traveling near c)

Assimov was very careful to sepperate that from his hyperspace fiction.

[TheVat]

Technical analysis of this kind is useful IF we have reason to assume that a civilization millennia ahead of us still uses impulse rocketry for starfaring.  So that assumption deserves scrutiny as well.  

Getting whacked by an interstellar proton does seem like a potentially serious problem, especially von Neuman machines with nanoscale engineering.  Imagine a civ has molecule scale memory and you are stored as a miniature thumb drive aboard and after a thousand parsecs you're full of flipped bits or whatever.  Woops, there goes third grade...there goes first kiss...

1 hour ago, dimreepr said:

Assimov was very careful to sepperate that from his hyperspace fiction.

Asimov.  One S.  Yes, hyperspace was a handy sci-fi workaround.  Plenty of sci-fi writers took that route - Niven, Herbert, Heinlein, Clarke, et al.  Such a story device is called rubber science .

https://en.wikipedia.org/wiki/Rubber_science

[swansont]

14 minutes ago, TheVat said:

Technical analysis of this kind is useful IF we have reason to assume that a civilization millennia ahead of us still uses impulse rocketry for starfaring.  So that assumption deserves scrutiny as well. 

I think we have to limit ourselves to known physics. If you extrapolate based on something new being discovered, all bets are off. Energy? No problem - we find out that over-unity is possible! Warp drive! Stable wormholes! Impervium! Mithril!

[TheVat]

25 minutes ago, swansont said:

I think we have to limit ourselves to known physics. If you extrapolate based on something new being discovered, all bets are off. Energy? No problem - we find out that over-unity is possible! Warp drive! Stable wormholes! Impervium! Mithril!

Rubber science, for sure.  Except light sails, laser stations, the modes with external push.  Again, maybe why Von Neuman devices could be more feasible - one the size of a beer can, with light sail wings.  The physics is known, but I don't know how far the engineering will go.  We are talking civs with massively elongated time frames, a hypothetical entity at this point.  (shrug)

[swansont]

5 minutes ago, TheVat said:

Rubber science, for sure.  Except light sails, laser stations, the modes with external push.  Again, maybe why Von Neuman devices could be more feasible - one the size of a beer can, with light sail wings.  The physics is known, but I don't know how far the engineering will go.  We are talking civs with massively elongated time frames, a hypothetical entity at this point.  (shrug)

Solar sails feel a force of P/c, so you need ~3 x 10^9 watts to accelerate a 1 kg payload at 1g.  And a point source of light will drop off as 1/r^2

Solar sails are not really maneuverable - it will get you from point A to B, but if you want to do other than straight-line motion it gets tough. No stopping off to gather raw materials. Such efforts require additional infrastructure which adds mass.

[Mordred]

1 hour ago, swansont said:

I think we have to limit ourselves to known physics. If you extrapolate based on something new being discovered, all bets are off. Energy? No problem - we find out that over-unity is possible! Warp drive! Stable wormholes! Impervium! Mithril!

If we're sticking to known physics a  feasible possibility being the Alcubierre drive  it's feasible if one can solve the solutions for reduced energy requirements and eliminate any need for negative mass.

 Theoretically this would address the collision scenario as the spacetime bubble would cause deflection. However it also in turn generates a greater problem that the bubble may also cause gamma ray production. One study I'm familiar with showed that even at 50 percent c. That gamma ray production could wipe out life on the planet it's leaving and arriving at.

 However I've only ever come across the one paper on it.

Other than that I can't think of any viable means that isn't a 1 way trip. Which really negates curious visitations. Colonization would be far more likely than visitation in a 1 way trip scenario.

Though one other possibility is some species that lives strictly in space however that would require am extremely large craft with a huge infrastructure for resource production 

Edited May 4 by Mordred

[sethoflagos]

24 minutes ago, Mordred said:

... Though one other possibility is some species that lives strictly in space however that would require am extremely large craft with a huge infrastructure for resource production 

Like a customised self-gravitating body ~100+ km diameter built from carefully redirected small asteroids to put it into a path of ejection from the solar system?

Internal thermal energy may be a viable long term energy source (or nuclear). Deep subterranean accommodation caverns should give reasonable protection from small collisions.

Not sure I'd pick the lifestyle choice myself...

[Mordred]

Muc

9 minutes ago, sethoflagos said:

Like a customised self-gravitating body ~100+ km diameter built from carefully redirected small asteroids to put it into a path of ejection from the solar system?

Internal thermal energy may be a viable long term energy source (or nuclear). Deep subterranean accommodation caverns should give reasonable protection from small collisions.

Not sure I'd pick the lifestyle choice myself...

Much like that.  It's a feasible possibility one could gather resources as they go but it would have to be of sufficient size for any manufacturing of those resources. As well as population growth. 

 One could use the Oort cloud to hide in as their are lots of objects in the Oort cloud that escapes detection.

Edited May 4 by Mordred

[Moontanman]

14 hours ago, MigL said:

I like indulging nice guys, Moon, so I'll start us off.

Consider a constant acceleration ship, say 1g, for the confort of the occupants.

"From the planetary frame of reference, the ship's speed will appear to be limited by the speed of light — it can approach the speed of light, but never reach it. If a ship is using 1 g constant acceleration, it will appear to get near the speed of light in about a year, and have traveled about half a light year in distance. For the middle of the journey the ship's speed will be roughly the speed of light, and it will slow down again to zero over a year at the end of the journey.
As a rule of thumb, for a constant acceleration at 1 g (Earth gravity), the journey time, as measured on Earth, will be the distance in light years to the destination, plus 1 year. This rule of thumb will give answers that are slightly shorter than the exact calculated answer, but reasonably accurate."

From     Space travel under constant acceleration - Wikipedia

We can then make other quick estimates to travel time

"From the frame of reference of those on the ship the acceleration will not change as the journey goes on. Instead the planetary reference frame will look more and more relativistic. This means that for voyagers on the ship the journey will appear to be much shorter than what planetary observers see.
At a constant acceleration of 1 g, a rocket could travel the diameter of our galaxy in about 12 years ship time, and about 113,000 years planetary time. If the last half of the trip involves deceleration at 1 g, the trip would take about 24 years. If the trip is merely to the nearest star, with deceleration the last half of the way, it would take 3.6 years."

Now you might say"That's not too bad.". Only 113 000years pass on their home world to send a ship 100 000 light years. And a relatively short time to send it to a nearby star.
Even doubling that time for two-way journey seems reasonable.

Now comes the hard part.
( and I'm not going to attempt to quickly find/perform the calculation; I'll leave it to better, more fastidious, minds than mine )
How much Hydrogen do you need to carry, or collect along the way, in order to sustain a fusion reaction capable of sustaining a constant 1g acceleration/deceleration ?

I have to agree, near light speed travel is problematic for many reasons... why does this negate star travel?

5 hours ago, swansont said:

Also, how much reaction mass do you need to carry? What is the payload?

(At some point we get into the issue of how a craft survives hitting objects traveling near c)

What we need to do is justify thinking near c travel is necessary for star travel. 

Edited May 4 by Moontanman

[Mordred]

14 minutes ago, Moontanman said:

 

What we need to do is justify thinking near c travel is necessary for star travel. 

If you want turnaround to home planet in any reasonable time frame it's unavoidable even then its too slow for cosmological distances 

Edited May 4 by Mordred

[Moontanman]

9 minutes ago, Mordred said:

If you want turnaround to home planet in any reasonable time frame it's unavoidable even then its too slow for cosmological distances 

Turn around time has no bearing on the possibility of star travel, it only relates to the biological individuals involved. There doesn't need to be biological beings involved in the transfer from one start to another. 

[Mordred]

Do you want any information resulting from any studies  to return to home planet ? It doesn't matter if the occupants are biological or not in that regard.

What would be the point of any visitation if you cannot return with any data or resources 

Edited May 4 by Mordred