Tech levels and the end of the universe

[tomBitonti]

I'm presuming that you're referring to the link to the Copernican principle here, right? The wiki page for the Doomsday argument does go into detail about that, leaving aside its link to the page for it, so I'm not sure what the problem is. The other assumptions regarding the nature of the argument - such as a standardized average lifespan and the total capacity for how many people the Earth can support at one time - are plainly stated.

That's not the case for a probabilistic sampling, which (as I understand it) is premised on being able to keep most of the assumptions within a reasonably narrow band, so as to be able to use that to calculate likely values for the whole of the thing being determined.

This:

Denoting by N the total number of humans who were ever or will ever be born, the Copernican principle suggests that humans are equally likely (along with the other N − 1 humans) to find themselves at any position n of the total population N, so humans assume that our fractional position f = n/N is uniformly distributed on the interval [0, 1] prior to learning our absolute position.

Is suspect. Try doing a Bayesian analysis with prior and posterior distributions.

Thx!

TomB

 

[Alzrius]

This:

[...]

Is suspect. Try doing a Bayesian analysis with prior and posterior distributions.

It's a combination of an aleatory and epistemic probability...which the article notes.

You seem to be arguing that the prior distribution for the total number of humans that will ever live might be exponentially distributed (throwing off calculations regarding the Copernican principle's assumptions about where we are in the distribution of the total human population). In that case, you could have just pointed out that the article mentions that among the list of critiques, and we'd both have saved ourselves some posts.

 

[Sword of Spirit]

I glanced at the Doomsday argument article. My instinct says it's off.

I'm not a mathematician, and I'm not spending the 4 hours it would take to actually understand the nuances of the argument, but here are my main objections to it.

1. It appears to assume that humanity will be limited to one planet (earth).
2. It appears to accept as inevitable that humanity will come to an end.
3. It (depending on the actual details of the argument beyond my level of interest) either:
a) Assumes that the future of human experience will resemble the current and past experiences of humans and/or animals, or
b) Ignores such matters entirely and focuses purely on mathematical constructs.

In any case, I have a hard time seeing how a gross oversimplification of the infinite possibilities of the future (which we only imagine in sci-fi and fantasy) can in anyway provide 95% probability of anything other than hubris.

 

[Mishihari Lord]

So one weird (unintended) result of the current tech advancement scale in N.E.W. is that a species is never likely to die out due to the death of its own sun, collision of galaxies, or even the end of the universe, because such events are billions of years further into the future than any civilization's ability to deal with them are. I'm not 100% sold on that scale yet - still tweaking - but at 100th+ century we have the ability to survive, prevent, or cause the end of the universe; manipulation of dark energy (like Doctor Who scale stuff - Davros's "reality bomb", the Doctor "rebooting the universe"). At 51st century equivalent we have complete control over dark matter on a galactic scale, and the ability to restructure or move entire galaxies.

So even if I expanded those number vastly, we're still billions of years short of any problem occurring before a civilization can handle it. The sun will begin to die in 5 billion years - that's a long way away. The Andromeda/Milky Way collision is 4 billion years away. Various end of the universe theories are many, many billions of years away.

Of course' all of this assumes a soft-sci-fi/science fantasy setting. If your setting is harder sci-fi there's probably no getting around the end of the universe!

This needs more thought. A lot more thought!

I'm not entirely sure what you're looking for as input here, a way to tweak your scale or a way to ensure that not every race is immortal (although that would be alright for some settings) I'll make some suggestions for the latter, as they're more fun to think about. If you don't want races to last forever, there are quite a few ways you could postulate that they end which we don't currently have the understanding to refute with any degree of certainty.

• They could lose interest in reproduction and just die out
  
• They could be destroyed by their own creation, a la Berserker by Saberhagen.
  
• They could be destroyed by someone else's creation, a la Berserker by Saberhagen.
  
• They could encounter someone with a significantly higher tech, a la The Excession by Banks (or Cortez and the Aztecs for that matter)
  
• The event where two universes with different levels of vacume energy hit each other (I forget what this one is called) Basically, there's a wave of total destruction moviing faster than light, so if you don't have FTL you never even see it coming.
  
• The good old mundane war of mutual destruction.
  
• A natural threat coming from outside the universe, or outside the paradigm of known universes. I'm thinking of how Superman is invulnerable to just about any physical threat, but he's just as susceptible to magic as anyone else.
  
• The race gets bored with being all-powerful and evolves into something else.
  
• The race evolves socially into pacifism or VR navel-gazing. Then the some barbarians come along and destroy them. (Niven's recent Fleet of Worlds is not quite this, but observing how the Puppeteer race is held hostage is educational)

I guess what it comes down to is that if you're going to allow magic-level technology, than of course non-magic-level events aren't going to be a challenge. That's kind of the point of magic-level technology. If you want a real threat to folks with magic technology you need to make up some kind of magic-technology threat.

 

[Janx]

I love the idea that we can saying things like "latching onto reality between two points" and nobody blinks an eye! But yeah, conceptually that's up in the 14-ish level.

Meanwhile, they're arguing about an article about how long humanity may survive on the basis that the objectors didn't like the final number.

I was reading Starplex recently, by Robert J Sawyer. There, humans from trillions of years in the future sent stars back in time, enabling them to effectively "create mass" in the present by doubling up stars, and halt the expansion of the universe. It was an odd concept, but kinda groovy.

It seems to me that some chunk of the significant tech a species has is to solve big picture problems like climate change, pollution, baldness, universal expansion, stellar death, transportation, disease, genetic defects, not having a date to the prom, and so on in a way that actually works.

Just consider the loneliness issue. Let's say a species took a serious look at divorce rates and the problems some people have finding a true LifeMate. Sure there's some folks who make it work, but most people, not so much. With sufficient technology, a species can solve this in a way that doesn't get the guy laughed at for taking a robot to the Prom because he couldn't get a date.

Instead, a person is scanned and a suitable LifeMate is generated from the ground up with the right DNA and right emotional programming so when they awaken and and lay eyes on each other, they know they've found their one true love. Initially, the population count will increase by 50% as all the single or unhappily married fix their situation (remember, these are real, new people). After that, parents will make plans for their offspring to get a LifeMate by this technology. Perhaps seeding it into the local population so they can be high school sweethearts, or injecting the generated person back into the time stream to solve a person's particular difficulty in relationship finding. A family might raise two babies, one natural, one generated, just to set up a natural dynamic for the pair (they won't assume this is incest, because they know better).

This is the kind of out of the box invention that Doctor Who gets involved in. It's another reason he doesn't like guns, as those are just too blatantly brute force.

 

[Alzrius]

I glanced at the Doomsday argument article. My instinct says it's off.

Instinct versus science, round two. Fight!

I'm not a mathematician, and I'm not spending the 4 hours it would take to actually understand the nuances of the argument, but here are my main objections to it.

1. It appears to assume that humanity will be limited to one planet (earth).

That's not really relevant to what's there. The idea that humans would leave the Earth at some point would adjust the particulars of the DA only in that it'd increase the total capacity for how many humans would be alive at once (e.g. 20 billion people collectively supported across two planets, rather than 10 billion people supported across one). In that case, you simply adjust the calculations and modify the final results accordingly.

2. It appears to accept as inevitable that humanity will come to an end.

It's not an inevitability by the terms of the article, just a likelihood (e.g. 95%). Given that it's plausible to state that only a finite number of humans will be born - rather than an infinite number - the premise of the article certainly seems reasonable.

3. It (depending on the actual details of the argument beyond my level of interest) either:
a) Assumes that the future of human experience will resemble the current and past experiences of humans and/or animals, or
b) Ignores such matters entirely and focuses purely on mathematical constructs.

I'd say that it's option B, since it's not particularly concerned with questions of how humans would theoretically come to an end. It is, as you note, a purely mathematical construct, which is sort of the point. If you presume (as noted above) that there won't be a unlimited number of humans, then it's a question of trying to make a construct to guess how many there will be, and working backwards from there.

In any case, I have a hard time seeing how a gross oversimplification of the infinite possibilities of the future (which we only imagine in sci-fi and fantasy) can in anyway provide 95% probability of anything other than hubris.

I suspect that the hubris is in assigning humanity "infinite possibilities of the future" and in presuming that even loose models of statistical analysis don't apply to us, but that's just me.

 

[tomBitonti]

It's a combination of an aleatory and epistemic probability...which the article notes.

You seem to be arguing that the prior distribution for the total number of humans that will ever live might be exponentially distributed (throwing off calculations regarding the Copernican principle's assumptions about where we are in the distribution of the total human population). In that case, you could have just pointed out that the article mentions that among the list of critiques, and we'd both have saved ourselves some posts.

Actually, I was using as a prior distribution a uniform distribution. Thinking through the maths quickly ...

A problem seems to be that in a uniform distribution, all points are distinguished. A point in the middle is distinguished by being in the middle; a point at either end is distinguished by being on the end. That is, the Copernican principle seems to be mis-applied. Here average is not the same as undistinguished.

A second problem is that with just one sample, the posterior distribution has no time to converge to a good distribution. There aren't enough samples to overcome a bad prior distribution.

A third problem is that the posterior distribution seems to have as most likely that the selected point is the maximum of the distribution.

A fourth problem is that the posterior distribution, while it does favor a single point, seems to be very flat. In any case, the shape of the posterior distribution matters here, and we are given no details to it.

Thx!

TomB

 

[Alzrius]

Actually, I was using as a prior distribution a uniform distribution. Thinking through the maths quickly ...

To be clear, are you saying that you were using uniform distribution for the prior distribution, and that you think that this was in error for this problem? Because that seems to be what you're saying here, and I want to be certain I understand your position.

A problem seems to be that in a uniform distribution, all points are distinguished. A point in the middle is distinguished by being in the middle; a point at either end is distinguished by being on the end. That is, the Copernican principle seems to be mis-applied. Here average is not the same as undistinguished.

Right, this is Caves' rebuttal, which says that "the uniform distribution assumption is incompatible with the Copernican principle, not a consequence of it."

As that section notes, not saying where you're applying the Copernican principle is a weakness in the basic argument as presented, but this merely calls for the stated refinement of the principle, rather than its rejection. Though this admittedly flattens the model (which you do mention).

A second problem is that with just one sample, the posterior distribution has no time to converge to a good distribution. There aren't enough samples to overcome a bad prior distribution.

A third problem is that the posterior distribution seems to have as most likely that the selected point is the maximum of the distribution.

These largely solve themselves if you make the above change and presume that the uniform distribution is not a bad prior distribution.

A fourth problem is that the posterior distribution, while it does favor a single point, seems to be very flat. In any case, the shape of the posterior distribution matters here, and we are given no details to it.

It still doesn't call all values equally likely though, so at worst you would say that it offers a wider range of possibilities (and becomes less informative) since you're saying that the population up until now is less informative (but not completely uninformative) about the potential total population of all humans ever born. Having, as an example, 50% probability in the results generated (if you use this method) rather than 95% is a significant reduction, but not to the point of calling the exercise worthless.

 

[Morrus]

Meanwhile, they're arguing about an article about how long humanity may survive on the basis that the objectors didn't like the final number.

That's OK; we can talk round them!

It seems to me that some chunk of the significant tech a species has is to solve big picture problems like climate change, pollution, baldness, universal expansion, stellar death, transportation, disease, genetic defects, not having a date to the prom, and so on in a way that actually works.

Just consider the loneliness issue. Let's say a species took a serious look at divorce rates and the problems some people have finding a true LifeMate. Sure there's some folks who make it work, but most people, not so much. With sufficient technology, a species can solve this in a way that doesn't get the guy laughed at for taking a robot to the Prom because he couldn't get a date.

Instead, a person is scanned and a suitable LifeMate is generated from the ground up with the right DNA and right emotional programming so when they awaken and and lay eyes on each other, they know they've found their one true love. Initially, the population count will increase by 50% as all the single or unhappily married fix their situation (remember, these are real, new people). After that, parents will make plans for their offspring to get a LifeMate by this technology. Perhaps seeding it into the local population so they can be high school sweethearts, or injecting the generated person back into the time stream to solve a person's particular difficulty in relationship finding. A family might raise two babies, one natural, one generated, just to set up a natural dynamic for the pair (they won't assume this is incest, because they know better).

This is the kind of out of the box invention that Doctor Who gets involved in. It's another reason he doesn't like guns, as those are just too blatantly brute force.

I do enjoy high concept sci-fi which deals with these concepts we just don't consider -- yet. I mean, the end of the universe has been dealt with in fiction lots of times (makes it no less interesting though); but tiny problems, too can be really interesting. And that's assuming we even still resemble modern humans with the same desires and goals.

 

[Dungeoneer]

In any case, the shape of the posterior distribution matters here, and we are given no details to it.

I've always felt that the shape of the posterior distribution matters a lot!