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  #71  
Old 24th January 2017, 10:16 PM
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hackenslash hackenslash is offline
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Default Re: Need to be a full atheist

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Spearthrower said View Post
As for warp drive, I don't see that something which is apparently fictional can really be a basis for solid consideration. Maybe it's possible, who knows? I would expect that there'd be other ways to travel with sufficiently high tech, but I might just be making up sci-fi!
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The Alcubierre drive or Alcubierre warp drive (or Alcubierre metric, referring to metric tensor) is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve apparent faster-than-light travel if a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created.
Rather than exceeding the speed of light within a local reference frame, a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel. Objects cannot accelerate to the speed of light within normal spacetime; instead, the Alcubierre drive shifts space around an object so that the object would arrive at its destination faster than light would in normal space without breaking any physical laws.[1]
https://en.wikipedia.org/wiki/Alcubierre_drive

In the 1990's I corresponded with Marc Millis at NASA who was running a warp drive and alternate propulsion group at NASA. He went on to form the Tau Zero Foundation. https://tauzero.aero/
The big problem with Alcubierre's metric is that the energy requirements are such that you'd need an Alcubierre drive to build an Alcubierre drive, which seems a bit of a stumbling block.

There was a fair bit of discussion on this at RS with Twistor, Campermon et al.
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  #72  
Old 24th January 2017, 11:40 PM
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Default Re: Need to be a full atheist

You wouldn't want to collide with anything, even extremely rare gas or dust.

Where does one aim toward and how do you slow down, how long does it take to do so?

This has to be performed within safe G-force.

One wouldn't be able to communicate or get back home. Nothing would be learned.
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  #73  
Old 25th January 2017, 05:00 AM
Spearthrower Spearthrower is offline
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Default Re: Need to be a full atheist

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Science is not prescriptive. The loophole is reasonable and we may be able to exploit it.
Sure, but it once again is rested on the term 'if'. My point is that we don't know. That's really all my point is. If we don't know whether something is valid or not, operating as if it were is surely best left to science fiction?


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Given that other species may have evolved technological civilisations a million years ago or more then if there is a way to do it then they may have done it already.
Or they may not have done it because it's not possible which would explain the Fermi Paradox, or they might not be bothered to, or they might not exist.

For me personally, I find it important to use caution when stacking a possibility on top of another possibility, where neither possibility can actually be measured. We simply don't know. It's plausible that there are technological aliens, it's plausible there may be a way to circumvent the maximum speed, it's plausible that there may be aliens exploring the galaxy, but it's exactly as plausible that none of these things are true.
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Old 25th January 2017, 05:17 AM
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Default Re: Need to be a full atheist

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You seem to consider a "long time" and "a really long time" as different problems.
Yes. It's a long time to walk down the shops, but quite another proposition altogether to visit Andromeda.

Space is, well, big - thanks Mr Adams.


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There are life forms on Earth that don't age, although they get killed off by disease and accident.
And get worn down by the passage of time just through wear and tear.

However, these candidate species, such as Turritopsis nutricula are incredibly simple - and their immortality is achieved by reverting back cyclically to a budding form, almost like an embryo. Kind of like a butterfly going back to its infancy caterpillar form.

Another point to note is that we don't actually know they are biologically immortal as we haven't studied them long enough. We do know how they can evade aging for some time though.




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If a non-aging life form became technologically advanced they would be able to mitigate disease and accident. That could make a million year trip within their remit. They could perhaps stop in useful solar systems to repair ship systems, maybe drop colonies off that would build new ships in time. At 50% of the speed of light then one side of our galaxy to the other is a 200k year trip and slightly shorter by the clocks on the ship.
Again, and really with no disrespect, I think this is the provenance of science-fiction. When I say no disrespect, I mean that I am considering shifting gears, stopping work, and investing my time and money to write a sci-fi book, so I really don't mean it in any dismissive sense.

However, I don't think such speculation really informs us of anything, it just lets our imagination run free.

I would say the odds are better that there is no such species than there is such a species. My rebutal to the contrary would be to point at the sky and say 'where are they then?'

So really, all I am saying here is that yes, we can imagine lots of things, but we don't know whether those things are real or even potentially real.
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  #75  
Old 25th January 2017, 10:07 AM
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DanDare DanDare is offline
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Default Re: Need to be a full atheist

Hi Azu, I hope you don't mind that we are continuing this discussion about space travel in the thread. It is at least marginally relevant, I hope, to your OP.

So lets discuss the attitude of hard science, critical approach verses speculation (which is not sci-fi as sci-fi can include the plausible impossible).

My epistemology works with the idea of supported claims that have not been shown false. And I apportion belief in the manner suggested by Hume the produces the pithy "extraordinary claims need extraordinary evidence".

However when speculating it changes, because you are experimenting and exploring. Then you are not "accepting" things into your knowledge but looking to the boundaries and trying to find the delta just on the safe side of impossible. The value of doing that is that it drives exploration. The danger of doing that is that people can confuse it for "making a claim".

Let me go back to the UFO discussion.

People see things and suggest they have seen alien visitors from elsewhere. We are discussing the "other worlds" elsewhere here in the thread though there is the "other universe/dimension" trope that I think we all mostly dismiss.

In evaluating if Alien Visitors is even worthy of consideration we look to the chain of elements that we would need to accept.

1) Intelligent, technological life having evolved elsewhere
2) A means for that life to travel across the vast distance of time and space
3) The possibility that at least one such species would be motivated to undertake the journey.
4) That the reported sightings could match the expected behaviour and materiality of said explorers.

I think 4) is a killer for the idea of alien visitors. Even after you filter out most of the sightings (to borrow from Hyneck, daylight discs, night lights, close encounters of the 1st, 2nd and 3rd kind) the few unexplained phenomena do not concord with our expectations of either intelligent beings visiting or automated probes either. Most close encounters fit well within the realms of human psychology and concord more with fairies and elves.

That almost by itself kills the discussion but its interesting to look at the other parts anyway.

I think 1) is not considered by anyone here as a stretch, our present understanding of abiogenisis suggests that life itself may be moderately common. Although we only have a sample of 1 species being technological we have samples of multiple species with varying degrees of intellectual capability. That would suggest that given many worlds with life we could accept the possibility that life became intellectual and technological on a few of them. We do not need sound, supported evidence of 1) as we are only requiring it to be on the safe side of impossible, and its much safer than that.

That leaves us with 2) and 3) which we are discussing at length.

Fermi's "Paradox" (they should be out there and visiting us often but they don't seem to be) places some extra "impossible" bounds on 2) and 3) because aliens do not appear to be everywhere in space and do not appear to have visited us (if you accept my rebuttal of case 4).

That suggests the following:

possibility a: 2) and 3) are both possible but due to some contingency they just have never come here or left evidence of their presence. That is really, really implausible but still fits on the safe side of impossible.

possibility b: 2) is impossible so however much any life form want to travel from star to star and visit or colonise it just can't happen.

possibility c: 3) is impossible and no species is willing to spare the cost of sending individuals or automated probes ever. I won't include here that it is too expensive. I see that possibility as an element of 2).

So our own interest in exploring space suggests to me that possibility c is not so. I am going to claim that we have enough evidence to show that a species being motivated to send individuals and/or probes is on the safe side of impossible.

Possibility b would require that we can think of no plausible way for life to travel interstellar distances. Note that the distinction between automated probes and passenger ships is a sub issue but we can discuss that later.

Von Neuman machines, self replicating, self repairing automated probes travelling at slow speed through space, are certainly a possibility well on the safe side of impossible so possibility b is axed totally. With our current technology we could propel such things at a speed that would get them across the galaxy in about a 10 million years or so.

So given that b and c are not so that leaves possibility a. They are out there, there is a way for them to be here. It just hasn't happened.

So our discussion of ways it could happen with life forms on board hinges on the speed and logistics of travel and the life span and motivations of the travellers.

I propose the possibilities of:

generation ships containing viable population levels and biosphere. This has a problem of life sustaining energy sources (often discounted in the speculation). I don't know if the energy source problem puts us into the impossible realm or not.

Suspended animation. From what we can tell complete suspension of chemical activity is impossible. Somewhere there is an upper limit to that even if it can be done. We have no idea of what that upper limit is but we know there will be a distance limit based on the intersection of suspension time limits and maximum speed (this side of impossible). Generation ships combined with suspended animation could extend the range if the generation ship energy problem can be beat.

Non-aging life forms. This is not about wear and tear but about the ability of a biological entity (or a machine system) to maintain itself in its prime state by internal renewal. On Earth we have simple microbial examples but also larger, more complex life forms such as the bristlecone pine, the ocean quahog (molusc), the American lobster, and some tortoises. They do not exhibit "senescence" where repeated biological cycles gradually degrade the system. They still suffer damage but we know of biological systems that can repair differing amounts of damage. The big obstacle is disease, and that may evolve to overcome biological systems on very long journeys.

Would any such creatures be motivated to make such journeys? That seems like its on the safe side of impossible. There are humans who say they would if they could.
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Burden of proof is the obligation on somebody presenting a claim to provide evidence to support its truth (a warrant). Once evidence has been presented, it is up to any opposing "side" to show the evidence presented is not adequate. If claims were accepted without warrants, then every claim could simultaneously be claimed to be true.

History isn't written by the victors. It's written by the people with the time machines.
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  #76  
Old 25th January 2017, 01:12 PM
Spearthrower Spearthrower is offline
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Default Re: Need to be a full atheist

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DanDare said
However when speculating it changes, because you are experimenting and exploring. Then you are not "accepting" things into your knowledge but looking to the boundaries and trying to find the delta just on the safe side of impossible. The value of doing that is that it drives exploration. The danger of doing that is that people can confuse it for "making a claim".
For clarity here, I wasn't under any impression you were making a claim, and I was well awayre that you were speculating.

My point is that our lack of knowledge is not a good basis on which to build an extended series of plausibilities because they actually become less and less plausible the more that are stacked.

If I want to say that A might be possible, then well and good. But if I say B might be possible when B is contingent on A being true, then I've started down a path of imagination that becomes continuously more abstracted from any reality we might be hoping to reference. When we get to C, which is contingent on B being true, which is contingent on A being true, I don't see what the value of the discussion has with respect to defining possibilities. It's well beyond what we can know and so, to me, it becomes an exercise in the limitations of what can be said, or what can be imagined, and therefore something more creative than useful to any notion that it is being used to support.


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DanDare said
In evaluating if Alien Visitors is even worthy of consideration we look to the chain of elements that we would need to accept.

1) Intelligent, technological life having evolved elsewhere
2) A means for that life to travel across the vast distance of time and space
3) The possibility that at least one such species would be motivated to undertake the journey.
4) That the reported sightings could match the expected behaviour and materiality of said explorers.

I think 4) is a killer for the idea of alien visitors. Even after you filter out most of the sightings (to borrow from Hyneck, daylight discs, night lights, close encounters of the 1st, 2nd and 3rd kind) the few unexplained phenomena do not concord with our expectations of either intelligent beings visiting or automated probes either. Most close encounters fit well within the realms of human psychology and concord more with fairies and elves.

That almost by itself kills the discussion but its interesting to look at the other parts anyway.
This is much like what I am driving at here. Statement 4 is contingent on 1-3 being true, there is no independence in statement 4 that isn't geneticaly founded in the preceding statements, none of which anyone can say is true or false and could well be wholly our imaginations.


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I think 1) is not considered by anyone here as a stretch, our present understanding of abiogenisis suggests that life itself may be moderately common. Although we only have a sample of 1 species being technological we have samples of multiple species with varying degrees of intellectual capability. That would suggest that given many worlds with life we could accept the possibility that life became intellectual and technological on a few of them. We do not need sound, supported evidence of 1) as we are only requiring it to be on the safe side of impossible, and its much safer than that.
I would say that this is the point to be speculated about. We don't know even this. Is life actually an incredibly rare phenomenon that is more than just the presence of chemicals. Does it take a suite of circumstances to happen? Given the distribution of species in kingdoms across our planet, should we really expect to see intelligent life, or would it be more realistic to assume microbial.

For me, this is the point where speculation is fecund, and maybe stepping into what kinds of life might be, what kind of intelligence might we see, whether there is any extraterrestrial species with the capacity to do technology.

But when we get to the point where we're discussing whether a specific species can break the laws of the universe insofar as we know, and start discussing this merits of speculative technology they might have if they exist.... I think we've moved firmly into science fiction. I don't think it has any bearing on the originating topic of the question of life in the universe, and I don't think it's fertile as it can't really provoke us to do anything with it beyond more speculation.

Don't get me wrong, as I said, to me there's a whole field of entertainment predicated on the enjoying speculation of alternative life forms with alternative technology, but I am not sure how it's of any use in terms of really answering the question of where are they?

Quote:
I propose the possibilities of:

generation ships containing viable population levels and biosphere. This has a problem of life sustaining energy sources (often discounted in the speculation). I don't know if the energy source problem puts us into the impossible realm or not.

Suspended animation. From what we can tell complete suspension of chemical activity is impossible. Somewhere there is an upper limit to that even if it can be done. We have no idea of what that upper limit is but we know there will be a distance limit based on the intersection of suspension time limits and maximum speed (this side of impossible). Generation ships combined with suspended animation could extend the range if the generation ship energy problem can be beat.

Non-aging life forms. This is not about wear and tear but about the ability of a biological entity (or a machine system) to maintain itself in its prime state by internal renewal. On Earth we have simple microbial examples but also larger, more complex life forms such as the bristlecone pine, the ocean quahog (molusc), the American lobster, and some tortoises. They do not exhibit "senescence" where repeated biological cycles gradually degrade the system. They still suffer damage but we know of biological systems that can repair differing amounts of damage. The big obstacle is disease, and that may evolve to overcome biological systems on very long journeys.

Would any such creatures be motivated to make such journeys? That seems like its on the safe side of impossible. There are humans who say they would if they could.
That is a perfect example of what I mean!

We don't know that any of those are possible, so how does it help us address the other question which it is seeking to expand on? More importantly, how do we then move on from speculation to motivations for the speculated creatures which possess speculated technologies and speculated cellular regeneration?

Surely at some point in those steps we acknowledge to ourselves that we've moved into a different realm of thinking.

The only one there that we have any knowledge of is the question of biological aging, and we don't even really know much about that. We've found some species which undergo transformations that are different than ours and which consequently help stave off cellular senescence, but we don't know that they can do this indefinitely, or even for a very long time. From what we do know, maybe we could speculate about whether such cellular regeneration is possible in larger, more complex creatures like ourselves, but I don't think we could take it as being established to explain that therefore it's possible that alien civilizations might use this to traverse space.

It begins to be a too complex web of speculation that, to me at least, has little bearing on reality and is just more of an exercise in what we can imagine.
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