Philosophical implications of inflationary cosmology

by on March 18, 2006 at 6:55 am in Philosophy, Science | Permalink

Recent developments in cosmology indicate that every history having a nonzero probability is realized in infinitely many distinct regions of spacetime. Thus, it appears that the universe contains infinitely many civilizations exactly like our own, as well as infinitely many civilizations that differ from our own in any way permitted by physical laws. We explore the implications of this conclusion for ethical theory and for the doomsday argument. In the infinite universe, we find that the doomsday argument applies only to effects which change the average lifetime of all civilizations, and not those which affect our civilization alone.

Got that?  Here is the paper.  Here is brief background.

It seems if you count all possible universes (or call them parts of our multiverse, whatever) as normatively relevant, none of your actions matter in consequentialist terms. 

As to how our world, and our decisions, matter at the margin, we delve into the murky waters of infinite expected values.  With an infinity of alternatives out there, our little add-on doesn’t seem to make any difference for the grand total.  Why should even you raise the average outcome across universes?  (TC yesterday: "No, Bryan, we are not leaping up Cantorian levels of infinity, it is just one version of you getting another Klondike bar.")

One option is that only our universe, or some other "in-group," matters.  The other universes cannot count for less, rather they must count for nothing.  I recoil at such a thought, but it does avoid the mess of infinities.  Alternatively, we might embrace some version of Buddhism. 

On the bright side, philosophic talk about modality is no longer so problematic but rather refers to facts about other existing universes.  Since that problem threatened to bring morality to its knees anyway ("what do you mean, you "could" have done something different?  You did what you had to do."), maybe I don’t feel so bad after all.  And who should care if I do feel bad?  The other me feels fine.  Infinity has its benefits, and there are many worse problems.

You should lower your probability that God exists, since the Anthropic Argument will dispense with the Argument from Design.  Only the ordered pockets of the multiverse can wonder about why we are here and why things seem to run so smoothly.

That’s a lot to swallow in one day, but it seems the probability of all those propositions just went up.

Addendum: Have I mentioned that inflationary cosmology and its implications fit my crude, pathetic intuitions?  Since we have a universe, I feel it must somehow be a kind of cosmic "free lunch."  And once you open the door for free lunches, why stop at just one?  There is no good reason to rely on our locally-evolved common sense intuitions when doing philosophic cosmology.

1 Tom March 18, 2006 at 9:15 am

Two concepts that have consistently receded over the centuries are “the infinite” and “god”. Lots of things we thought were infinite turned out, on closer inspection, to be finite. The size of the world, the size of the universe, and the age of the universe for three. So let me just predict here that the “infinitely many distinct regions of spacetime” will sooner or later become “large but finite”, and the whole consequentialist dilemma goes away, no matter how large the number is.

Plus, I’ll take these kind of discussions more seriously when someone can tell me *reliably* what the weather will be tomorrow.

2 Macneil March 18, 2006 at 1:30 pm

Tyrone is posting as Tyler now!

3 Ronald Brak March 18, 2006 at 9:52 pm

“And who should care if I do feel bad?”
Why should you feel bad if the universe doesn’t?

If everything that can possibly happen happens in some universe, then low probability universes must vastly
outnumber reasonable probability universes. And since the combination of positions and energy levels of
the basic units of my fingers are fairly limited if they stay attached to my body, universes in which my
fingers do not spontaneously become an expanding ball of plasma must be incredibly rare. So while you
could cut off your own fingers to save you in another universe from having to cut off your own fingers,
any universe in which Tyler has fingers at all is exceptional. Indeed, any universe in which Tyler isn’t
killed by someone else’s fingers turning into a random expanding ball of plasma is also incredibly rare.
So I say if you are one of those incredibly rare Tylers who has fingers, do your best to enjoy them while
you have them. You owe it to the infinite number of Tylers whose fingers randomized.

If all possible things that can happen happen, then anyone who is capable of thinking at all is likely to
be obliterated the next instant. This would suggest that we should all increase our discount rates to
massively high levels. However, because our chance of obliteration is so high, it simply is not worth
the effort to change our discount rate. My advice is just keep on enjoying your life as best you can for
if you are capable of enjoyment at all you are an incredibly rare gem in an infinity of dross.

4 Alex Tabarrok March 18, 2006 at 11:00 pm

Since nothing we do can possibly affect people in other universes, whether spatially, temporally or dimensionally distinct it makes perfect sense to count utility in those universes as zero.

Alex

5 A Tykhyy March 19, 2006 at 12:21 am

Remember, this whole inflation stuff is a hypothesis, essentially supported only by the microwave background data and a load of wishful thinking.

6 Nick Borst March 19, 2006 at 3:34 am

It seems that there a lot of very speculative claims being thrown around recently.

Most recent example: http://news.bbc.co.uk/2/hi/science/nature/4819370.stm

It must have something to do with a wish to attract some of the attention and funding that string theory (another highly speculative theory) has received.

Astronomers and physicists must think that if they can make fantastical claims and attract enough public attention they will be able to obtain funding for these risky projects that otherwise would be left unfunded.

7 Tyler Cowen March 19, 2006 at 8:56 am

See the Bostrom piece at the link, pp.16-17 for a good response to Alex and some of the other comments.

8 Barkley Rosser March 19, 2006 at 9:39 am

Tyler,

I think you already answered Glaivester in implying that
we are dealing with countable universes (this is not a story
of going to Cantorian higher levels of infinity), although we
are taking your word for that.

Regarding the relevant pages you just emphasized. OK. I have
not read the underlying lit on inflation theory, so maybe it is
true that this latest observation is consistent with a theory of
infinite universes with “all possible futures” happening “within
our own spacetime” (and hence immune to agnosticism about modal
realism).

Nevertheless, I would say that from the standpoint of ethics,
intentions connected to reasonable probabilities of cause and
effect regarding one’s own actions (I defended free will a while
back on one of your earlier threads) should be the basis for morality
and ethics. It may be that some day we will understand our causal
links with these other subsections of our universe. But until that
time we have no idea what connection anything we do has to them, if
any. Hence, we should pay attention ethically to the links that we
do understand and worry about them. Certainly the possibility of these
more cosmic links does not undo our responsibility (“here on earth in
this piece of spacetime”) for those we do know about and maybe can do
something about.

9 Jthaddeus March 19, 2006 at 3:41 pm

You do not have to think much of the fine-tuning argument to see that the multiverse response to it is a bit sophomoric. The usual, and more or less sound insofar as it goes, response to the fine-tuning argument is that one cannot infer design just because the probability of the universal constants is low. To infer that, one needs to know the prior probability of design versus non-design. Just as one can’t from winning a lottery that it was rigged in your favor (because of the high prior probability that it was NOT rigged), one can’t infer design from low probability constants.
The multiverse argument, however, seems to concede just this point, and then attempts a very bad alternative refutation of the fine-tuning argument. It argues that one can infer non-design due to the high likelihood of the distribution of intelligent, seemingly-designed beings (i.e. beings like us) in the universe. This is bad, first of all, because it commits the same logical error, turned on its head, as the regular fine-tuning argument: it infers non-design from a high likelihood on non-design without reference to any prior probability. And secondly, because it doesn’t realize that the fine-tuner can simply move his probability arguments up a notch and argue that a machine capable of producing any distribution of finely-tuned being would have to be finely-tuned itself. Thus, I see no good reason, based on these or any other current cosmological findings, why anyone should alter their estimations of the design argument or any other argument about God.

10 Nathan Zook March 20, 2006 at 12:33 pm

Bostrom’s work fails on so many levels that it is hard to manage. In order for a being to reason about infinite consequences, he must have information about those consequences. While our hubris is great, we really cannot discuss ethics of those who can process infinite data.

I have a positive discount rate on a dollar in the future not because it makes my series converge, but because _I don’t know_ if I’ll really get the dollar or not. My discount on Aid to Africa ™ is high firstly because _I don’t know_ if my aid will get there or rot on the docs.

Any reasoning about the effects of my actions outside my light cone is superstition. And reasoning which attempts to place significanct value on causality within my light cone but removed more than a very limited degree is rank speculation.

The claim that the universe is truly infinite is highly suspect, and in any event cannot be observed. Plenty of manifolds are closed, a fact which we should not dismiss. All the claims relating to the likelihood of the existence of multiple or infinte like observerses rely on this claim. But they also rely upon a presumption of uniformity of energy distribution in this setup. Again, a difficult presumtion.

Oh, the odds of Alex’s fingers exploding are quite low in every observerse in which physics is coherant enough for Alex to exist in the first place. Rearrangements can make the external probability whatever you like, but that doesn’t change the internal probability.

11 Ronald Brak March 20, 2006 at 11:59 pm

“[T]he odds of Alex’s fingers exploding are quite low…”

But if everything that can happen does happen in some universe, then surely the protons in his fingers must spontaneouly decay in many of them? If Alex’s fingers remain as conventional fingers over say the next second, then the number of different universes branching off from his fingers will be quite limited compared to the number of possible universes that will result if they happen to under go an extremely improbable explosion. If everything that can happen happens, no matter how improbable, then wouldn’t universes where everything explodes for no adequately explained reason be the most common sort?

Now some people might say that I don’t know what I’m talking about, and there’s a very good chance that they’d be right. But I guess there is a very small chance that I’m currently in a universe where I’m making some kind of sense. (Ooh look! Flying pigs!)

My idea may sound kind of silly,

12 Ronald Brak March 22, 2006 at 12:19 am

Interesting. Looks like I’ll have to hit the books, Nathan. (Now where did I put my club?)

13 Jeremy Pierce April 16, 2006 at 10:59 pm

Now that I’ve had a chance to come back to this and read your argument carefully, I have one comment on the ethics. I think you’re assuming something that I wouldn’t grant. The argument is that the net result wouldn’t be any different if I did an action usually considered better worse, and therefore the action isn’t really better or worse because the consequence of either action would be the same.

Now anyone who denies consequentialism isn’t going to buy this. Just because two actions lead to the same consequences doesn’t mean they’re morally equivalent. Your argument rests on the consequence being the same, as if that’s the only morally relevant issue. Non-consequentialists won’t accept that.

But the other problem is one I think a consequentialist might even accept. Consequentialists don’t always believe that my action’s moral value depends just on whatever future state of the world occurs afterward. It depends, for many consequentialists, on which aspects of the future state of the world have something to do with my action. If my action causes the bad, then I am to blame. If it causes the good, I’m to be evaluated positively. So if I’m the one who does the bad thing, and some duplicate of me in another part of the multiverse does the good thing, then I’m to blame and he is to be congratulated. So my action is bad even if my not doing it would logically (but not causally) entail someone else doing it and lead to an exactly similar result somewhere else. That means we should blame the one who does the bad thing, even if the overall multiverse isn’t going to be different just because one particular person in one of those worlds did it this way rather than another way.

14 bbn November 14, 2006 at 7:22 am

MEGSPASE

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