Szydagis' point 3: Interstellar travel is too hard

[Mauro]

Well, there's silicon-based, but that should result in a pretty inflexible critter. And since every life form with which we are familiar consists very largely of water, anything without water would similarly be inflexible. Water is a great solvent for all the components we need for life to move around and get together, but I suppose it would be possible to have another solvent do the trick.

I think that water and carbon would be a necessity,

I 100% agree with you.

Silicon, yeah, it might support a biosphere, but it's a very long stretch (very much very long, imho, even if it was fun to play Silicoids in Master of Orion...). Water is so amazing a solvent, with added amazing physical properties (enormous thermal capacity, positive expansion coefficient when freezing, etc.) that it's hard to envision any biological system which can do without it, but it's pretty lousy at dissolving silicon compounds. I'd say life needs carbon+water with 99.9% (add any number of 9's at your pleasure...) probability.

but not necessarily DNA as we know it. If there is other life out there, it might contain the same components, but arranged in an entirely different method.

Yeah, DNA could be different (possibly, but it's a pretty outstanding molecule by itself and difficult to replace), bases could be different (there's even a whole array of different bases used by Earth life beyond the canonical GATC-U) and the genetic code could probably be different (but here too there are some constraints). Surely 'DNA' and protein sequences would be different, while I guess most basic biochemical pathways (and the use of ATP and of basic transmitters, Ca++, NO, even adrenaline and the like) would be quite similar. But who knows, i'd so much like we knew more

 

[Mendel]

@Ann K my idea was that at different pressure/temperature combinations, other molecules could act as solvent that wouldn't work on Earth.

 

[Eburacum]

...the genetic code could probably be different (but here too there are some constraints).

Even in Earth's biosphere there are 33 different codes. Obviously the phase space of possible genetic codes is quite large; some say it is very large, so large that every planet in the Visible Universe could have a slightly different code. But that would be difficult to prove.

...my idea was that at different pressure/temperature combinations, other molecules could act as solvent that wouldn't work on Earth.

Here's an online book that discusses this possibility in some detail. Water is a great solvent, and very common in cosmic abundance; but it is not the only one.
https://nap.nationalacademies.org/read/11919/chapter/8
(eighth chapter of a 100 page book)

But if a solvent other than water were the matrix for life, and if that solvent tolerated C=N units, would life not have been able to evolve in that solvent to exploit C=N units just as effectively as terran life today exploits C=O units?

 

[Scaramanga]

My maths didn't depend on the probability. The probability *cancels out*. If all you're fussing over is the probability, then you have no attack on my argument. And no, this was not a bayesian argument, I've been quite clear about when I'm using bayes, and this wasn't one of those times. You've provided no evidence my assumptions are false, which means, if you're following cold heartless maths, you ought to come to the same conclusions as me. That you're failing to do that means that you disagree with my assumptions, but have no proof they're false. I of course consider my assumptions to be the ones that one would adopt in the absence of any knowledge to the contrary. Feel free to try and persuade me to change that stance - but that will require evidence that not even the astrophysicists have.

The entire 'there must be other life out there' argument is based upon a large numbers fallacy. We have two numbers...

1) The number of inhabitable planets in the universe
2) The probability that life will form on any inhabitable planet

We have a few reasons to believe that (1) may he huge.....in the order of 10^18 or something like that. Maybe more, maybe less, but a large number all the same. It is that large number that leads to 'surely there must be other life out there'....from people who mathematically ought to know better !

For the simple fact is that we have no idea what ( 2) is. We simply do not know if life forming even under the right conditions is a less than 10^18 number and life is common.....or is 10^6432. Compared with which the 10^18 we are impressed with is tiny !

You cannot assert that "It is highly improbable that it's 1 in 10^527"...because 10^527 may actually itself be tiny compared with the actual number. The fact that we have a sample of 1 proves ONLY that the number is not infinite.

 

[Scaramanga]

you'd be indistinguishable except for your history
nobody could prove you're not you

that's why cars carry serial numbers

Nobody has ever yet made a car that can occupy the identical physical space of another car. My car is uniquely identifiable because of the Pauli exclusion principle....no matter how 'identical' another car is. And the same applies to bodies. I am uniquely 'me' because even the most identical copy of me cannot occupy the identical space and time. A copy can never do so, and thus always remains a copy and not the original.

 

[Eburacum]

One of John Wheeler's more interesting postulates was that there is only one electron in the universe, going backwards and forwards in time.
https://en.wikipedia.org/wiki/One-electron_universe
It may be that there is only one sentient being in the universe going backwards and forwards in time. I doubt that very much, just as I doubt the one-electron universe, but I don't think we have enough information to disprove these ideas conclusively.

 

[Mendel]

Nobody has ever yet made a car that can occupy the identical physical space of another car. My car is uniquely identifiable because of the Pauli exclusion principle....no matter how 'identical' another car is. And the same applies to bodies. I am uniquely 'me' because even the most identical copy of me cannot occupy the identical space and time. A copy can never do so, and thus always remains a copy and not the original.

The practical problem arises when you try to devise an operational test that can determine who the real Scaramanga is, and who the copy. If the copy is perfect enough, then there cannot be a history-agnostic test that solves this problem.

As a hypothetical, if you walk into the copy machine, and two identical Scaramanga walk out with no indication which one walked in, then there'd be no scientific way to distinguish the copy from the original.

 

[Ann K]

As a hypothetical, if you walk into the copy machine, and two identical Scaramanga walk out with no indication which one walked in, then there'd be no scientific way to distinguish the copy from the original.

If everything were copied, down to the synapses and memories, each one could then tell you - honestly - "I was the one who walked into the copier", and "I am the real Scaramanga".

 

[John J.]

It may be that there is only one sentient being in the universe going backwards and forwards in time. ... I don't think we have enough information to disprove these ideas conclusively.

I think we probably can disprove that there is only one sentient being going backwards and forwards in time, if we accept that sentience is entirely dependent on a biological substrate possessing physical extent, mass and organisational complexity.
All the comments made above about the difficulties of time-travel would apply.

 

[John J.]

Of course, there is a sort of counter-argument in the form of a 'Ship of Theseus' bit by bit replacement

Ship of Theseus thought experiment on Wikipedia here https://en.wikipedia.org/wiki/Ship_of_Theseus

Some British people of a certain age, most with little knowledge of philosophy, will know an analogous example,
"Trigger's broom". Trigger has received a medal from his employer, the local council, for looking after his work equipment:


Source: https://www.youtube.com/watch?v=LAh8HryVaeY


Uploaded by YouTube user MarkAlzano c. 2014, originally from BBC 1980s sitcom Only Fools and Horses.

 

[JMartJr]

Or, in a different context, the Axe of Rhys, Low-King of the Dwarfs of Discworld:

"This, milord, is my family's axe. We have owned it for almost nine hundred years, see. Of course, sometimes it needed a new blade. And sometimes it has required a new handle, new designs on the metalwork, a little refreshing of the ornamentation . . . but is this not the nine hundred-year-old axe of my family? And because it has changed gently over time, it is still a pretty good axe, y'know. Pretty good."

― Terry Pratchett, "The Fifth Elephant"

 

[Ann K]

Some British people of a certain age, most with little knowledge of philosophy, will know an analogous example,
"Trigger's broom". Trigger has received a medal from his employer, the local council, for looking after his work equipment:

My father, growing up during the depression in a Scottish family with no money to spare, said that he would get new soles on his boots, then get new uppers on the soles, then get new soles...

 

[Vlcek]

If everything were copied, down to the synapses and memories, each one could then tell you - honestly - "I was the one who walked into the copier", and "I am the real Scaramanga".

One of them would end up standing in the area of the copying device where the machine outputs the copies, and that clone would have the memory of being there in that location. The other one wouldn't.

It's just like the person in Star Trek who appears on the "teleporter pad" and knows that they've been beamed up or down. The copy would know that they've been "beamed" into existence while the original would have no such experience.

 

[FatPhil]

For the simple fact is that we have no idea what ( 2) is. We simply do not know if life forming even under the right conditions is a less than 10^18 number and life is common.....or is 10^6432. Compared with which the 10^18 we are impressed with is tiny !

You cannot assert that "It is highly improbable that it's 1 in 10^527"...because 10^527 may actually itself be tiny compared with the actual number. The fact that we have a sample of 1 proves ONLY that the number is not infinite.

But having one datapoint is *absolutely not* having "no idea". Please go and read the thread about bayesian statistics, the documents linked to therefrom, and then review what you have written with a view of the credence your numbers would be given.

 

[Mauro]

But having one datapoint is *absolutely not* having "no idea".

But it's already been demonstrated this single data point does not allow any probability calculation at all, it can only say that P(life) is not zero.

Please go and read the thread about bayesian statistics, the documents linked to therefrom, and then review what you have written with a view of the credence your numbers would be given.

The point is: any number has a very low credence because we have no meaningful way of calculating one.

We can only give a very broad range: from ~1:10-1:1000, or any analogous number, down to 10^-(number_of_planets_in_the_universe + K), with K not too big or the probability of our own existence would become too small. There's no reason, at the moment, to prefer one number over another (my personal feeeling is the upper probability limit will decrease drastically the more knowledge we get, while the lower one will stay the same, but who knows).

 

[FatPhil]

But it's already been demonstrated this single data point does not allow any probability calculation at all, it can only say that P(life) is not zero.

The point is: any number has a very low credence because we have no meaningful way of calculating one.

We can only give a very broad range: from ~1:10-1:1000, or any analogous number, down to 10^-(number_of_planets_in_the_universe + K), with K not too big or the probability of our own existence would become too small. There's no reason, at the moment, to prefer one number over another (my personal feeeling is the upper probability limit will decrease drastically the more knowledge we get, while the lower one will stay the same, but who knows).

To a bayesian, a single data point does allow a probability calculation. You're right, that calculation leaves you with a very broad range, one you can't do any useful calculations with, but you're not left in the state of "we simply know nothing about the probability". A slight hump is different from flat, no matter how slight the hump is. And of course, it's not a slight hump at all, as we have a huge number of almost certainly negative data points too. There definitely are reasons, at the moment, to prefer one range of numbers over other ranges of numbers.

 

[Mauro]

You're right, that calculation leaves you with a very broad range, one you can't do any useful calculations with, but you're not left in the state of "we simply know nothing about the probability".

I think this is a good basis for an agreement

 

[FatPhil]

I think this is a good basis for an agreement

Absolutely. The progress we're making finding and analysing exoplanets, and understanding solar system formation, leads me to hope that we aren't too far from having numbers with narrow enough error bars that useful calculations can be made. I hate the Drake equation, but some of the terms we're starting to be able to narrow down to a few orders of magnitude.

 

[John J.]

To a bayesian, a single data point does allow a probability calculation. You're right, that calculation leaves you with a very broad range, one you can't do any useful calculations with, but you're not left in the state of "we simply know nothing about the probability".

This has to be right.
I've always liked "the German tank problem" as a relatively simple example of the use of Bayesian analysis
(and I think it's an interesting historical tale too), Wikipedia https://en.wikipedia.org/wiki/German_tank_problem,
where Allied intelligence in WW2 tried to estimate German tank production numbers- rather accurately, it turns out.

The Wikipedia article does discuss the rather obvious limitations of a single tank as a data source.
But even if, implausibly, only one tank was found, it would demonstrate that an enemy tank exists, and so the chances of there being more, though formally incalculable, must be increased.

@FatPhil's criticism of the Drake equation is well-founded, until very recently it's been more descriptive (listing relevant variables) than predictive; the possible numerical range for any given variable was too large based on our limited knowledge.
As Phil says, this might be starting to change as we gather information about extra-solar planets.

The rapid appearance of life on Earth- well within the first billion years of a solid crust (post-Theia), maybe within a few hundred million years- might be a statistical fluke, or it might be an indication that life can arise with relative ease in conditions resembling those of early Earth.

I do wonder if intelligence might be as unique to us (H. sapiens) as, say, the markings of a particularly distinctive butterfly.
It might be an emergent property, but dependent on the very specific systems underlying our perception, memory, language use and problem-solving. The Neanderthals were very similar to us, yet their Levallois-Mousterian toolkit hardly changed in a quarter of a million years. The more sophisticated Châtelperronian industry is associated by some with Neanderthals, but paradoxically arrived near the end of their existence (meaning that a sudden flowering of refined technology didn't improve their survival prospects), and some think the Châtelperronian artefacts are in fact H. sapiens Aurignacian artefacts.

Teleological interpretations of evolution are almost certainly incorrect. Even if life is common in our galaxy, and evolution allows for increasing organisational complexity, I'm not sure that intelligence/ consciousness like ours is necessarily a common result.
After all, there are many different ways to be alive in our 3.5+ billion-year old biosphere demonstrated by millions of eukaryotic species right now, but only one quite young specie reflects on this.

 

[Mauro]

The rapid appearance of life on Earth- well within the first billion years of a solid crust (post-Theia), maybe within a few hundred million years- might be a statistical fluke, or it might be an indication that life can arise with relative ease in conditions resembling those of early Earth.

Indeed, it's hard to make anything out of that. It's another single data point and even if it's strong at first sight it suffers too from an argument which is (again) related to survivorship bias.

It's true that life on Earth originated (much probably) within the first ~500 million years, a remarkably short time which points to life being not that improbable, but it's also true that the first lifeforms able to have questions about the origin of life (us) were born ~4 billions years later, and in just ~500 more million years the conditions on Earth will be no more hospitable to life, due to the Sun aging and increasing its luminosity. So it might be that the mean time for life to originate (given a suitable world around a Sun-like star) is actually long (thus life is rare), but only where it happens early there's the chance for a sentient race to evolve before the local star burns everything out. Or it might be the other way, with life common and we unlucky humans born near the Sun expiration date for a statistical fluke, we just don't know.

 

[John J.]

in just ~500 more million years the conditions on Earth will be no more hospitable to life

If our technological society persists for just another million years, and we haven't sent any operational craft to a solar star system by then, (1) maybe that will be evidence for Szydagis' point 3 (although admittedly on the basis of 1 data point ) and (2) I'll want a refund.

 

[Mendel]

Or, in a different context, the Axe of Rhys, Low-King of the Dwarfs of Discworld:
"This, milord, is my family's axe. We have owned it for almost nine hundred years, see. Of course, sometimes it needed a new blade. And sometimes it has required a new handle, new designs on the metalwork, a little refreshing of the ornamentation . . . but is this not the nine hundred-year-old axe of my family? And because it has changed gently over time, it is still a pretty good axe, y'know. Pretty good."
― Terry Pratchett, "The Fifth Elephant"

Yours and @John J.'s are examples of identity established through history.

One of them would end up standing in the area of the copying device where the machine outputs the copies, and that clone would have the memory of being there in that location. The other one wouldn't.

Yeah, but that's not possible in my hypothetical example that @Ann K commented on: "with no indication which one walked in"

 

[Vlcek]

Yours and @John J.'s are examples of identity established through history.

Yeah, but that's not possible in my hypothetical example that @Ann K commented on: "with no indication which one walked in"

Even with no indication of which one walked in, each of the individuals who comes out know who is who. Because one of them has a distinct memory of being in the "input chamber" and then suddenly being in the "output chamber" without any in-between action - they must have been cloned. There's no way to hide this from them unless we contrive some sort of amnesia but that seems like a bit of a narrative trick and beside the point.

 

[NorCal Dave]

Even with no indication of which one walked in, each of the individuals who comes out know who is who. Because one of them has a distinct memory of being in the "input chamber" and then suddenly being in the "output chamber" without any in-between action - they must have been cloned. There's no way to hide this from them unless we contrive some sort of amnesia but that seems like a bit of a narrative trick and beside the point.

Do they? Just spitballing here, but if the idea is that after walking into the "input" chamber a clone is created that has ALL of the original guy's memories up until the point the clone is created, then we know they would both have the exact memory of walking into the "input" chamber. At this point they are indistinguishable.

Now IF the chambers have big signs saying "input" and "output" inside of them, then I suppose the clone would have the memory of walking into the "input" and then seeing the words "output" in his chamber while the original only sees "input". As you say, the clone would have slightly different memory following walking into the "input". However, if the chambers are indistinguishable, then maybe not. If there is no clue or clear delineation for the clone to create a different memory right after being cloned, he would think himself as original as the original, right? They both walk out with the memory of walking in, so to each one they are the original and the other guy is the clone.

And even if there was something like an "output" sign for the clone to see, modern research has shown that memories are very malleable and change quite often. If our clone is being told he's just a clone because he was in the "output" chamber, he may well begin to remember walking into and OUT of the "input" chamber, making him just as original, if not THE original.

 

[Mendel]

Do they? Just spitballing here, but if the idea is that after walking into the "input" chamber a clone is created that has ALL of the original guy's memories up until the point the clone is created, then we know they would both have the exact memory of walking into the "input" chamber. At this point they are indistinguishable.

@Ann K made this point earlier, in the post that @Vlcek first quoted. Maybe Vlcek using amnesia as a narrative trick?

We could also Ship-of-Theseus the copy mechanism: split the original Skaramanga down the middle and then generate the missing halves.
Kinda like taking an axe apart, attaching a new handle to the old blade, and a new blade to the old handle.

My point is still that we're trying to establish who the 'real' @Scaramanga is by determining a continuity from the old Scaramanga to one of the new ones, but if that is the only distiction between them, no-one but Scaramanga is going to care about it.

 

[John J.]

With our human replicator machine, I guess we can (theoretically) suppose that the original person might be scanned, and the information saved, down to the atomic level. But we can't record the quantum states of the individual atoms or subatomic particles without changing them in the process, so it'd be difficult to make a duplicate in whom all the constituent particles have the same quantum state as the original.

Just as we can't send information by checking the polarisation of entangled particles, I can't think of a way of using the divergent quantum states in the original person and the copy to identify which is which.

But, philosophically speaking, might the continuity of (albeit ever-changing) quantum states in the original (which we will leave unchanged, as there is no point in attempting to record and duplicate them) mean that the original person has the greater claim to continuity of identity?

I don't know if building our duplicate with quantum states necessarily different to those of the original will have any biological, and possibly cognitive, effects. While we're familiar with the idea of individual quantum states affecting macroscopic outcomes- Schrödinger's cat- maybe in large objects without too many unstable nuclei, the numerous quantum states are just background noise, rarely affecting activity at the molecular level, or at the level of neuronal firing etc.
Mathematician Roger Penrose has claimed that consciousness is based (directly) on a quantum-level substrate, but this is a minority view and his proposed mechanism- quantum effects in microtubules- has arguably been refuted by Tegmark and others,
https://en.wikipedia.org/wiki/Roger_Penrose.

A different issue, maybe getting us back toward interstellar exploration:
Suppose we send our duplicator, or a machine capable of building a duplicator from local resources, via some conventional nuts-n-bolts method* to a habitable planet** of some nearby star.

A suitably-qualified and trained volunteer is scanned, and the information describing their physical being is transmitted at c to the replicator. -I'll skate over the fact that's a lot of information that would need to be received perfectly; might take a while.
Our copy awakes, and sharing the motivation and training of the original, starts their duties.

But after some time, our clonenaut*** starts getting a bit despondent. Whatever information they send to Earth will take years to get there, and any grateful response years to come back. Entertainment is limited. (I guess we might suppose that the descriptions of several people are sent, and saved by the replicator, so it can construct a few people in short order).
Though habitable in a broad sense, the alien environment presents a host of challenges and hazards, some unforeseen, that require near-constant consideration and efforts to mitigate their impact.
There is no external help, and any request for additional equipment or personnel will take many years to be fulfilled.
Time to relax is rare, and every so often a new threat or problem arises, taking a toll on the equipment, health and mood of the clonenauts, who have memories of their lives on Earth and realise there's no going back.

They start thinking, "Why did I volunteer for this?"- and realise, they didn't.
Unlike, say, a "conventional" astronaut, a serviceman or a scientist in Antarctica, the original volunteers are not facing the hardships and risks of their decision to take part. They remain safe at home, their "others", who were never in a position to give informed consent, face a lifetime of struggle without any prospect of returning to the home of which they have fond memories.

The clone of a specialist plumber who arrived sixteen years into the program, after the initial arrivals found that their plastic piping was prematurely ageing due to some local factor, is furious that life in the colony has been misrepresented to her (subjectively a few days before but actually some years earlier), and starts having issues about her memory of happily receiving a huge payment for "her" participation.

We should take action now, no exploitation of clonenauts!
And support for the future inhabitants of generation starships if they decide to turn round and come back- they didn't consent to a life of duty and privation for themselves and their children.


*Which- as many above posts argue- would be at best immensely difficult, and take a very long time as far as we can tell.
**Assuming one exists.
***(c) John J.

 

[jdog]

With our human replicator machine, I guess we can (theoretically) suppose that the original person might be scanned, and the information saved, down to the atomic level. But we can't record the quantum states of the individual atoms or subatomic particles without changing them in the process, so it'd be difficult to make a duplicate in whom all the constituent particles have the same quantum state as the original.

Just as we can't send information by checking the polarisation of entangled particles, I can't think of a way of using the divergent quantum states in the original person and the copy to identify which is which.

But, philosophically speaking, might the continuity of (albeit ever-changing) quantum states in the original (which we will leave unchanged, as there is no point in attempting to record and duplicate them) mean that the original person has the greater claim to continuity of identity?

I don't know if building our duplicate with quantum states necessarily different to those of the original will have any biological, and possibly cognitive, effects. While we're familiar with the idea of individual quantum states affecting macroscopic outcomes- Schrödinger's cat- maybe in large objects without too many unstable nuclei, the numerous quantum states are just background noise, rarely affecting activity at the molecular level, or at the level of neuronal firing etc.
Mathematician Roger Penrose has claimed that consciousness is based (directly) on a quantum-level substrate, but this is a minority view and his proposed mechanism- quantum effects in microtubules- has arguably been refuted by Tegmark and others,
https://en.wikipedia.org/wiki/Roger_Penrose.

A different issue, maybe getting us back toward interstellar exploration:
Suppose we send our duplicator, or a machine capable of building a duplicator from local resources, via some conventional nuts-n-bolts method* to a habitable planet** of some nearby star.

A suitably-qualified and trained volunteer is scanned, and the information describing their physical being is transmitted at c to the replicator. -I'll skate over the fact that's a lot of information that would need to be received perfectly; might take a while.
Our copy awakes, and sharing the motivation and training of the original, starts their duties.

But after some time, our clonenaut*** starts getting a bit despondent. Whatever information they send to Earth will take years to get there, and any grateful response years to come back. Entertainment is limited. (I guess we might suppose that the descriptions of several people are sent, and saved by the replicator, so it can construct a few people in short order).
Though habitable in a broad sense, the alien environment presents a host of challenges and hazards, some unforeseen, that require near-constant consideration and efforts to mitigate their impact.
There is no external help, and any request for additional equipment or personnel will take many years to be fulfilled.
Time to relax is rare, and every so often a new threat or problem arises, taking a toll on the equipment, health and mood of the clonenauts, who have memories of their lives on Earth and realise there's no going back.

They start thinking, "Why did I volunteer for this?"- and realise, they didn't.
Unlike, say, a "conventional" astronaut, a serviceman or a scientist in Antarctica, the original volunteers are not facing the hardships and risks of their decision to take part. They remain safe at home, their "others", who were never in a position to give informed consent, face a lifetime of struggle without any prospect of returning to the home of which they have fond memories.

The clone of a specialist plumber who arrived sixteen years into the program, after the initial arrivals found that their plastic piping was prematurely ageing due to some local factor, is furious that life in the colony has been misrepresented to her (subjectively a few days before but actually some years earlier), and starts having issues about her memory of happily receiving a huge payment for "her" participation.

We should take action now, no exploitation of clonenauts!
And support for the future inhabitants of generation starships if they decide to turn round and come back- they didn't consent to a life of duty and privation for themselves and their children.


*Which- as many above posts argue- would be at best immensely difficult, and take a very long time as far as we can tell.
**Assuming one exists.
***(c) John J.

So that big "DNR" tattoo over your heart means "Do Not Replicate"?

 

[John J.]

So that big "DNR" tattoo over your heart means "Do Not Replicate"?

Don't be silly, my doctor told me it means "Deserves Nurse Romance". They treat you better if you agree to the tattoo, she said.

 

[Mendel]

There's a Calvin&Hobbes where Calvin wants his clones to do his chores and homework for him, but it turns out they don't like it either...

 

[Ann K]

There's a Calvin&Hobbes where Calvin wants his clones to do his chores and homework for him, but it turns out they don't like it either...

You bring to mind Disney's Fantasia, the segment on The Sorcerer's Apprentice, in which Mickey learns to clone:

 

[JMartJr]

Have we reached the point where "Speculation on Cloning" needs to be detached from "Interstellar Travel is Too Hard?"

 

[Mendel]

Have we reached the point where "Speculation on Cloning" needs to be detached from "Interstellar Travel is Too Hard?"

Interstellar Travel is Too Hard on Clones

 

[John J.]

Well, I enjoyed my earlier ramblings immensely, but I guess we should get back to interstellar flight being difficult (and opinions otherwise).

 

[Ann K]

Have we reached the point where "Speculation on Cloning" needs to be detached from "Interstellar Travel is Too Hard?"

No, I think we have reached the point where we should just shut the whole thing down. Since it's all based on speculation anyway (interstellar travel, energy development, likelihood of aliens, chemistry of aliens, and cloning - we have been all around the mulberry bush with this one), it's unlikely that any more factual material will crop up soon.

 

[captancourgette]

This is an updated version of my reply from an earlier thread. The Fermi Paradox comes up eventually on every astronomy and space forum and social media site I visit so I now keep a canned response on file.

Hope this helps.

Sorry I've been on holiday (without ~real internet in france, BTW I do take full credit for the election results )
Mate Sorry I think you may of misunderstood me, due to my mention of the fermi paradox and you perhaps focusing on that phrase , sorry I was talking about the question commonly associated with that paradox 'where is everyone'. And cause my mind works different than most folks, So bare/bear/beer with me.
Now Ignore the universe, Lets just focus on just the galaxy (cause this breaks down when you consider inter-galaxy travel) gulp! but OK ignore that, as its not important for the point I talk about cause the numbers are so big anwyas that the spirit is the same

the milkyway has 100-400 billion stars (just trusting wiki for numbers)
it is ~90,000 lightyears across

I assume we are all in agreement with this?,
now my point is provided we can build a ship that can travel at ~10% the speed of light (impossible now, but not unthinkable in a few centuries time, esp cause its not a ship that carries humans)
and that its a van neumann machine (harder problem than the 10% lightspeed but not impossible in a few centuries time I assume)
OK these are 2 factors that we do not have but yet are both within the realm of achieve-ability the thing is once a society achieves both than running the numbners, treat it like a math 'equation' (wrong word) but its exactly like the fermi paradox, but even more simple cause there are fewer variables

Now suppose A & B to be true, how long to visit/colonize the milkyway (colonize = have presence, not ppl wise but have probes there spitting out van neumann bots, and the thing is since it cost you nothing if you visit you stay, i.e. its not machine X finds planet Y and then travels on to planet Z, no its machine X finds planet Y and then creates machines that go onto planet Z1,Z2,Z3,starZZ1,ZZ2 etc whilst it stays there churning out more and more probes from the elements it harvests)
the answer = they will have visited each planet in the galaxy within a few million years
^OK few may be doing some heavy lifting but its really a tiny fraction of the billions of years this gaklaxy exists

Now has this happened yet to us on earth?

perhaps, but I'm extremely doubtful, even though it only requires some race in the last ~10 billion years to achieve A&B for the milky way to have been 'visited/colonized' within the last few million years (are we the first special race?, I don't think so)
what have us humans visited so far? earth and the moon (slight jaunt) except these all our exploritories have been probes, So where is everyone?

 

[JMartJr]

earth and the moon (slight jaunt) except these all our exploritories have been probes,

To be fair to us, your post's possible alien explorers are just using probes too! Per your use of "colonize," we've colonized much of the solar system. So we're doing better than I'd known...

 

[Mendel]

that its a van neumann machine

you are talking about a von Neumann probe, or self-replicating spacecraft. A von Neumann machine is just a computer.

 

[Scaramanga]

But having one datapoint is *absolutely not* having "no idea".

Yes it is ! A single data point is only ever proof that something can happen once. It gives you zero information about the probability of that event happening again. And Bayesian analysis depends entirely on what priors are used. It's like the Drake equation, where people input figures they just made up off the top of their head, as they don't actually have a clue what most of the numbers actually are.

In my view Exobiology is on par with Alchemy as a 'science'. It has to be the only 'science' for which there is absolutely zero evidence for there to be a science about.

It's odd how often on this site it is argued that there's zero evidence aliens could get to Earth, yet few seem to want the equally scientific stance that there is zero evidence aliens even exist to come here in the first place. Alas a generation of watching Star Trek has clouded rational debate on the matter, and given the totally bogus impression that aliens are 'likely'.

 

[FatPhil]

Yes it is !

Wrong.

 

[Scaramanga]

If everything were copied, down to the synapses and memories, each one could then tell you - honestly - "I was the one who walked into the copier", and "I am the real Scaramanga".

Ah, but I see from my extensive notes that I answered this with a thought experiment years ago....

1) Do you wake up in the morning and ask yourself whether you are the same person who went to sleep ? No. I mean...why would you be ?

2) So why should the fact that a copy of you was made while you were asleep make any difference ?

3) Sure, the copy wakes up thinking he is you. But, in fact nothing has actually changed from the situation prior to copying being invented. OK so there's a copy out there who thinks he's you. So what ? It does not alter YOUR status at all. Nothing about you yourself has changed one iota from prior to copying. You wake up thinking that you are you...because you are !

4) The crux here is that people confuse what the copy thinks with your status..as if it somehow affected it. The fact that some copy thinks he is me is no more relevant to my status than some person thinking they are a re-incarnation of Napoleon or are Jesus.