Dark Energy

Dark energy keeps galaxies apart

Tim Radford
Saturday February 19, 2005

Guardian

It is invisible, undetectable and utterly inexplicable. It also adds
up to most of the universe. Cosmologists are looking for ways to
explore dark energy, a force that accounts for more than 70% of
creation, but so mysterious that seven years ago, no one could confirm
that it existed.

Dark energy is not the same as dark matter....
<snip>
It was predicted by Einstein but spotted only in 1998 when the Hubble space telescope found evidence....
The puzzle was not its existence but that it was present in such tiny
quantities, Leonard Susskind, of Stanford University, California, told
the AAAS yesterday.

Its existence could only be measured after decimal point followed by
120 zeros. This was an unimaginably small figure, but it explained why
humans existed.

"If it were ... 1,000 times bigger, we wouldn't be here ... because
galaxies couldn't have formed," said Professor Susskind. "This dark
energy is a repulsive force. If it was a billion times bigger it would
be terribly small but it would have destroyed the solar system."
http://www.guardian.co.uk/life/science/story/0,12996,1417867,00.html

Have I got the math right on this? It seems to me that what this article is saying is that if the measurement of dark energy in the universe was different by an infintesimally small percentage, human beings would not exist.

To calculate the percentage difference in the level of dark energy that would have eliminated the possibility of our existence, divide 100,000 by 10 to the 120th power. If I've got my sums right, it seems the scope for variation while preserving the possibility of human life is mind-bogglingly small.

It strikes me that this is why positing a multiverse is the only rational option a scientist can take to avoid the inference that the universe was intelligently designed---especially if the design has to be intelligent enough to make life like ours possible.

This is also the sort of scientific evidence that persuaded noted British philosopher Antony Flew recently to abandon atheism.

Susskind, the guy quoted in the article, is one of the leading proponents of the multiverse.

Essentially, the number of universes in the multiverse has to be practically infinite in order for it to be the case that the dark energy level in our universe has the magnitude it has *by sheer chance.*

Ironically, the multiverse essentially is an infinite and invisible thing posited to explain why we are here, and the explanation it gives is 'sheer chance'. I'm not sure how this is supposed to be simpler or more obviously true than positing one transcendent creative and ethical mind, but maybe that's just me.

Oh, and this multiverse type of explanation would only explain why things are the way they are physically in our universe. We'd still be left with the mind-body problem, morality, religious experience, and all that jazz.....such as the aesthetics of jazz. Why does any of this stuff arise from physical matter at all? Again, positing one transcendent creative and ethical mind seems a lot simpler and economical to me, explaining not only the astonishing fine-tuning of our physical universe, but also the existence of rational minds, moral value, aesthetic value, and religious experience. What's even more odd about the multiverse hypothesis is that if an infinite number of universes did exist, not one of them would exist for a mind-dependent reason. They'd just all be there for no reason at all. That notion seems utterly nutty to me, I must say.

At the very least, I think this dark energy calculation is the kind of empirical discovery that makes the theistic hypothesis not unreasonable.

As a footnote, I would add that there's a good case to be made that even positing a multiverse would not be sufficient to solve the fine-tuning problem. See this fascinating article for more on that.

ON EDIT: What's even more odd about the multiverse hypothesis is that if an infinite number of universes did exist, not one of them would exist for a mind-dependent reason. I suppose I should amend this to saying 'a materialist multiverse hypothesis', because there might be, among an infinite number of universes, some that are dependent for their existence on a mind or minds. But obviously that would conflict with materialism. However, the multiverse, as proposed by the likes of Susskind, Linde, and Rees, is meant to be a theory within physical science, and that's why I did not think it necessary earlier to add the qualifier 'materialist' to 'multiverse'. Multiverse standardly means a very large number of physical universes, all of whose ultimate causes or origins are purely physical.

But if one were prepared to abandon materialism so that there might be some universes in a multiverse which are mind-dependent for their existence, then it seems pointless to posit a multiverse in the first place---because the fine-tuning of this universe could just be explained by its dependence on a universe-transcending mind, with no need for chance to play an explanatory role in the selection of its basic physical parameters and laws. The multiverse is only invoked, standardly, to explain, by appeal to chance selection, how our universe's parameters and laws got to be the way the are, and thus without invoking a transcendent mindlike creator. It's very much a concept generated by the materialist explanatory paradigm.

Ironically, the multiverse essentially is an infinite and invisible thing posited to explain why we are here, and the explanation it gives is 'sheer chance'. I'm not sure how this is supposed to be simpler or more obviously true than positing one transcendent creative and ethical mind, but maybe that's just me.


:yourock:

Supposing huge quantities of dark matter and energy is the consequense of predictions of relativity and big bang theories.

The theory of Doubly Special Relativity, which is the strongest contender to dethrone Einstein, would make the dark problem go away.

One the one hand, if the math predicts it, we believe it's true. Sometimes. At least it's a nice, strong hypothesis (unless you're a Peircean, in which case it's not a hypothesis because it can't be tested, but it could be a theory, but few scientists, and fewer physicists, care about Peirce).

I have no trouble believing the multiverse hypothesis is true. Sort of a meaningless belief, to be honest, and if the math changes and so the multiverse becomes a quadriverse or something else, sure, why not. I think it's simply implied by the math, and people didn't do the math to make a multiverse so the probabilities work out ok. Look at the question from the tail instead of the head, and you'd conclude if the universe didn't have the properties, nobody'd be asking the question at all.

And, let's be clear. The current theories may be dust in a couple of years. Probably not, but theories are created, and if data disagree with them, and the theory can't be tweaked or the data disputed, out the old theory goes. Ultraviolet catastrophe, anyone? (I think it was ultraviolet.)

I have no trouble believing in an omnipotent Creator and that the math is possibly correct. The two beliefs have little to do with each other, until at least one is subjected to empirical tests.

Who says it could have been in an infinite number of pathways.

There may very well be "preferred pathways" or restricted pathways which limit the number of possible values to a finite number. For example, the influence of other constants or values could restrict the values for dark energy.

We just dont know, so we assume infinite values when that may not very well be the case.

If the possible values ARENT infinite, that may very well put a whole new spin on things.

Hell, anything's possible. But how likely is it?

A multiverse is invoked precisely because if you have got a big enough number of universes, then it's not surprising that one of them turns out to be like ours.

But yes, you could get a universe to be like ours if there were only a few even possible kinds of universe. Or, as physicist Frank Tipler and Brian Greene (the string theorist guy) have suggested, maybe there's only one logically possible possible universe, and maybe it is necessarily, or highly likely, instantiated, and maybe it's the one we're in.

But you see, this just ignores the problem.

The idea behind naturalism in this context is that the universe should be in no way anthropocentric. Or, to put it another way, the universe should not have had us humans in mind when it decided to instantiate itself. And it shouldn't have had us in mind because it (the universe) does not have a mind. There's no Big Mind there---that's the basic idea behind naturalism.

But look at what this implies! It implies that it just happens to be a fortuitous coincidence that the only way (or one of the very few ways) the universe COULD be, is ALSO a way that enables human life, complete with sophisticated universe-understanding powers of mathematical reasoning, to be possible and, indeed, actual.

In other words, although there was no, or very little chance, upon this hypothesis, that the universe could have turned out differently, it's just a COINCIDENCE that this narrowing down of the range of possibilities to a necessarily unique or near-unique way of how things could be happens to include us within it---and it's just a coincidence, because a) the universe didn't intend us, not being the sort of thing that can harbor intentions, and b) there's no other mind that could have harbored such intentions, on the naturalist worldview. We're just an accident of nature, on this view.

But wait a minute---the sophisticated theoretical physicist doesn't think that anything physical is really, truly a coincidence. There has to be some underlying mathematical rationality to everything physical, otherwise the theoretical physicist ain't buying it. But why should impersonal mathematical rationality care about human beings? Well, impersonal mathematical rationality would have no reason to care about human beings, of course!

That humans must or probably will emerge from the physics such mathematical rationality necessarily or very probably selects is an accident from 'the point of view' and of no concern to nonpersonal mathematics. Our emergence from the underlying math is, from that perspective, just a matter of sheer chance---this time, the sheer chance that mathematical rationality when instantiated physically has that consequence. The rationality isn't by chance--it's necessitated by logic, or reason, or math itself; but it just happens to be the case that this rationality also implies our existence. We weren't thought out or foreseen or wanted, etc.

And that seems, I think, to be simply too amazing, which is precisely why people turn to the multiverse idea instead. The multiverse makes it much less amazing or not amazing at all that we should be here.

But the multiverse comes with the price of being infinite, and hence being beyond experimental confirmation by finite observers. Which, of course, is the ironic thing about the multiverse hypothesis, as any theist will quickly note.