Showing posts with label multiverse. Show all posts
Showing posts with label multiverse. Show all posts

Monday, February 05, 2007

The Goldilocks Enigma - review by Inayat Bunglawala


Is life just an accident? A new book examines a variety of theories about the universe.

February 5, 2007 02:15 PM

In his latest book, the scientist and writer, Paul Davies, takes a look at why - like Goldilocks' porridge - the laws of physics appear to be "just right" for life to exist in the universe.

reposted from: Guardian
my highlights / emphasis / edits

If certain physical constants such as Newton's gravitational constant, G, or the value of the strong and electromagnetic forces in atomic nuclei, were only very slightly different from what they actually are, Davies says that the universe would have been quite unsuitable to support any form of life. Currently, there is no evidence that their values are anything other than a series of remarkable coincidences and it is understandable why many believers see in this a sign of a Creator.

Davies looks at a series of different models that might otherwise explain this fitness for life, including:

• The "absurd universe": the universe does mysteriously permit life, but that is just the way it is: there is no point to it, and if it had been any different, we would not be here to debate it. Life is merely an extraordinary accident. Davies says that this is "probably the majority position among scientists". Stephen Hawking encapsulated this view in his remark that "the human race is just a chemical scum on a moderate-sized planet".

• The "multiverse": there are an unimaginable number of universes apart from the one that we inhabit. Statistically, some would have the right conditions for life, while many, many others would not. We are lucky to be in one of the ones that permit life. Richard Dawkins expressed some support for this view in his book, the God Delusion.

• The "God hypothesis": many scientists find this an unsatisfactory position because although it may help explain why life exists, it merely replaces that with another big question. How did God come to be? The monotheistic faiths, including Islam, hold that God is a necessary being. "Vision cannot comprehend Him, yet He comprehends all vision," the Qur'an says.

• The "self-explaining universe": I'd have summarised this here if I could have followed what Davies was trying to say. But I couldn't.

To be honest, there were large parts of Davies' book where I was just hopelessly out of my depth. It came as something of a mild consolation when, after going through the different models, Davies admitted that despite his personal preference for the "self-explaining" universe model:
"... they all seem to me to be either ridiculous or hopelessly inadequate ..."

This is an understandable conclusion. Life is amazing. Consciousness is beyond amazing. The great physicist Richard Feynman perhaps expressed it most poetically:

I stand at the seashore, alone, and start to think. There are the rushing waves ... mountains of molecules, each stupidly minding its own business ... trillions apart ... yet forming white surf in unison.

Ages on ages ... before any eyes could see ... year after year ... thunderously pounding the shore as now. For whom, for what?...on a dead planet, with no life to entertain.

Never at rest ... tortured by energy ... wasted prodigiously by the sun ... poured into space. A mite makes the sea roar.

Deep in the sea, all molecules repeat the patterns of one another till complex new ones are formed. They make others like themselves ... and a new dance starts.

Growing in size and complexity ... living things, masses of atoms, DNA, protein ... dancing a pattern ever more intricate.

Out of the cradle on to the dry land ... here it is standing ... atoms with consciousness ... matter with curiosity.

Stands at the sea ... wonders at wondering ... I ... a universe of atoms ... an atom in the universe.

(Richard Feynman, The Pleasure of Finding Things Out)

Some reader comments.....


GBR

very interesting post inayat. some might add: if time is infinite then one might expect a universe like ours to turn up eventually.

but i agree with you. when one thinks of existence, life, and consciousness...what a wonder!


Since nobody else is going to I will say that I plump for the multiverse with the addition that, as with Scroedinger's cat, it is only when a self aware observer (us) comes into existence that a universe within the multiverse comes into "real" existence.

This perhaps somewhat extended recent blog http://a-place-to-stand.blogspot.com/2007/01/fermi-paradox.html gives my thoughts on this & its possible influence on the Fermi question (why haven't aliens arrived eons ago).


USA

THe weighing up of all available evidence points to the "Absurd Universe". There just isn't any evidence for the other three.

All evidence points to God being a man made idea.

There is no evidence of multiple universes.

The self explaining universe seems to me to be an scientists/atheists attempt to provide for our natural desire to find a higher purpose for life/existence.


USA

Another possibility is that the fundamental constants of the universe change with time. So at some point there's a good chance they'll be in a range where our sort of life can exist. I believe there were some papers on this last year or the year before.


GBR

Inayat, for a more interesting idea than the Goldilocks hypothesis, see the work of Lee Smolin. His evolving universes idea suggests that the laws of physics are *not* fixed and that we may indeed just happen to be in a universe suitable for life (for now). But it doesn't always have to be this way...

It's great stuff, and far more intellectually satisfying than cutting off inquiry by positing the God explanation each time.

This man may quite possibly rival Einstein in intellect and profundity:

http://en.wikipedia.org/wiki/Lee_Smolin


GBR

The universe is an accident. No intelligent designer would have come up with Pete Doherty. Or Jade Goody.


Sorry Cant Resist

There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.

Douglas Adams


GBR

"If certain physical constants such as Newton's gravitational constant, G, or the value of the strong and electromagnetic forces in atomic nuclei, were only very slightly different from what they actually are, Davies says that the universe would have been quite unsuitable to support any form of life."

What do we mean by "life"? And is there anything remarkable about it anyway?

We are atoms arranged into certain patterns. Our greatest ideas are patterns of electrical impulses. Our greatest art is merely re-arrangements of atoms, and our greatest feats of engineering and science just allow us to re-arrange more atoms faster, or produce different patterns of electrical impulses.

Viewed from the other side of the universe in a billion years' time we will be indistinguishable from all the other atoms and impulses.


GBR

This whole idea is daft - calculating the odds of the coincidences that came to allow life in it's present form to exist - all this rather pathetic line of thought has done is assume the present conclusion, life, is somehow unique, and must always be based upon mechanisms as found on earth at the present time.


So Inayat, god created all did he/it/her?

As regards patbatemans statement, ugly, offensive etc, just wanting to have a dig.

However, the comment regarding homosexuality; does not the Qur'an speak of god inventing man in all his differences, with only god able to judge him. If that is so where does religion fit into that statement? it does'nt!

Religion is just man's lust for power and immortality.

As regarding the universe: multiverse, with us only existing on one plane. Accretion theory for the planets, stars etc.

Why did god smash up the first universe?


DEU

Lacanian, still prefer the Anthropic Principle:

http://en.wikipedia.org/wiki/Anthropic_principle

Its such a no brainer ... excuse the pun!


GBR

This whole thing is based on the false premise that in order for life to exist it requires the exact same conditions as life on earth. There's no reason to think that whatsoever.

Extremophiles - archaea and so on - can exist in conditions of immense heat or cold, low oxygen, intense acidity or total aridity. There is some indication of recent liquid water on Mars and other parts of the solar system like Enceladus (moon of Saturn) where we had recently thought it impossible.

It's my suspicion that life is absolutely abundant in the universe, and that the Goldilocks Principle is fundamentally unsound.


GBR

If there is a massive explosion many thousands of fragments of debris may fly for miles. All except one may hit nothing of any significance and will be ignored. One fragment may hit the centre of a dartboard. That may be a bit of a freak occurance but it only seems "miraculously" amazing if you predicted, ahead of time, that this one particular fragment would hit this one particular dartboard.

If, on the other hand, you surrounded the explosion with dartboards, coconut shies, archery targets, boys with apples on heads and an infinite number of other possible targets and didn't specify any particular fragment or any particular end result then everyone yawns if one or another target is hit.

In other words you are looking at the end result and assuming that this was the desired end result.

Personally, I would have preferred an end result where people didn't make up religious cr*p without evidence and even kill people who had the temerity to not believe said religious cr*p.


If we take it that there is a God who created everything, he must be very clever. So why would he chose someone like Muhammad to be his prophet?


GBR

"� The "self-explaining universe": I'd have summarised this here if I could have followed what Davies was trying to say. But I couldn't.

To be honest, there were large parts of Davies' book where I was just hopelessly out of my depth."

--------------------

A-hahaha. If only all CiF bloggers were as honest.

Nick Cohen: "I'd like to turn my attention to justifications for the Iraq war, but to be honest I'm hopelessly out of my depth."

Madeleine Bunting: "If I knew more about Islamic theology I would explain these apparent inconsistencies, but to be honest I'm hopelessly out of my depth"

Martin Kettle: "It is important that we stand by Tony Blair at this time, and I would explain why but in all honesty I'm hopelessly out of my depth."

What a fantastic precedent!


USA

Suggest for a hilarious look at the Universe, the Books "Small Gods" & "The Last Continent" by Terry Pratchett. He created the "Discworld" science fantasy series, which features "Discworld", a flat world which rides on t he back of a giant turtle, which is supported by four elephants! Looking at our own "roundworld" from the perspective of the Small God "OM", a Turtle God, is not only a great romp, but for me a relief as an American, from the oppressive fundamentalist right-wing Christian funk of depression blanketing my own country!


GBR

kmir

"if time is infinite then one might expect a universe like ours to turn up eventually"

I don't think this follows necessarily. With my voice I can produce literally an infinite variety of sounds but, even given infinite time, I couldn't produce a realistic impression of the sound of a jet engine as the laws of physics wouldn't allow it.

Infinite time doesn't mean that all possibilities are bound to occur.


GBR

@Inayat
This is not one of your better constructed blogs but when you say "This is an understandable conclusion. Life is amazing. Consciousness is beyond amazing" it's very difficult not to agree with you.

Science has made great strides in understanding development of the universe in terms of its geography and topology, but consciousness is still an area where there is much work to be done.


GBR

"The "self-explaining universe": I'd have summarised this here if I could have followed what Davies was trying to say. But I couldn't."

As I understand it, this is derived from quantum theory - which posits that the act of conscious observation is necessary to collapse quantum indeterminacies (such as "the singularity") into (in this case) the physical universe.

There are two strands, one is that consciousness arose within the singularity, which immediately collapsed into the physical universe (the self-aware universe): the other is that we are currently creating the beginning of the universe by our attempts to observe it - iow, causation is running backwards in this regard (the boot-strap theory).

As a theory, it has, in common with "the God hypothesis" and elements of the "multiverse" theory (thank you 9percentGrowth) the assumption - shared, indeed, with most of the world's largest religions* - that consciousness is a necessary pre-condition to enable the universe to have come into existence (and to continue in existence).

(*Hence, in Genesis, it is "Light" (namely, consciousness) which turns chaos (darkness, the void, the deep) into the physical universe. It was even more explicit in the Egyptian traditions from which Genesis was copied.)

PatBateman

"Even if the universe was 'created', it wasn't created by somebody who expected adulteres to be stoned to death, women and homosexuals to be denied their rights, or who would send everybody who didn't do what he said to a place called hell."

I quite agree. Even if the universe was self-aware, I'm sure it would have better things to do than regulate the activities of this tiny part of it.

thetrashheap

"THe weighing up of all available evidence points to the "Absurd Universe". There just isn't any evidence for the other three. "

That might have been true 60 or 70 years ago, but science (quantum theory in particular) has become very "spooky" of late. It may turn out to be wrong, but there is certainly evidence to support it.


GBR


"One answer, a glib answer, is just to say well, god made them (the laws of physics) that way, end of story. Well it is of course the end of discussion if that's point of view you take."

Paul Davies. 5/11/2006

Glib : readily fluent, often thoughtlessly, superficially, or insincerely so.


GBR

!"the idea of marvelling at the wonder of life from a religious perspective isn't as divisive as they wish it to be."
Why from a religious perspective, Trendywhitebuddhist? The universe is wonderful enough without dragging god into it. Why only life? It's wonderful enough whether or not life- and Mr Davies only actually means life like us- a rather restictive definition- is an inevitability or a purpose of it or not.


GBR

!"the idea of marvelling at the wonder of life from a religious perspective isn't as divisive as they wish it to be."
Why from a religious perspective, Trendywhitebuddhist? The universe is wonderful enough without dragging god into it. Why only life? It's wonderful enough whether or not life- and Mr Davies only actually means life like us- a rather restictive definition- is an inevitability or a purpose of it or not.

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GBR

Inayat

It's easy to be taken in by the orderedness of "the world" but this is illusory.

To explain, if you led an urban existence you'd see a tiny, man-made window on the world. Venture into the [English] countryside and the illusion is maintained. The landscape is dominated by overgrazed fields, crops and planned forests. All is As It Should Be.

Now travel overseas to the snout of a glacier. Here you will find a chaotic tumble of dirty ice and boulders, constantly shifting. Beautiful yet threatening. Then cross a desert, an ice-cap or an ocean.

We consider this a life-sustaining planet but if I were transported to a random longitude and latitude I would be all-but-certain to drown, freeze or die of heat exhaustion in short order. If I were to materialise at random co-ordinates in space, then asphixiation would be overwhelmingly likely, followed by frazzling in a star.

Don't get me wrong - I'm not a nihilist by any stretch. I will still bounce out of bed tomorrow morning, ready to start another day. I'm just saying we shouldn't kid ourselves that the universe is more perfect than it really is. It's just the best one we know about.

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GBR

!"the idea of marvelling at the wonder of life from a religious perspective isn't as divisive as they wish it to be."
Why from a religious perspective, Trendywhitebuddhist? The universe is wonderful enough without dragging god into it. Why only life? It's wonderful enough whether or not life- and Mr Davies only actually means life like us- a rather restictive definition- is an inevitability or a purpose of it or not.

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GBR


Inayat :

I think physicists seem to make the most sense to non physicists when they
( almost ) write prose poems. Maybe we are hardwired to get meaning in this way.

Think of anything else well conveyed in layers of poetry to a mass audience?


Don't give up with them. Please.

Peace

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GBR

'...Davies says that the universe would have been quite unsuitable to support any form of life'

What supreme and unforgiveable arrogance. Given the (apparent) size and scope of the universe, the endless permutations and possibilities that must exist 'out there', and the (minumal) amount of knowledge we humans possess, how can a statement like that be justified? We know so little about the universe that most of it is labelled 'dark matter' because we have no other way of explaining it. Tis absurd to make statements like the above when we humans are but an insignificant flash in the pan who don't even understand our own origins, let alone that of the universe. One more point; since the universe has (allegedly) been expanding ever since the 'big bang', just what in the hell has it been expanding into?

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Triainus for intelligence you don't need human style life butyou do need an environment that is capable of sustaining sizeable complex life. We may well find microbes on Mars but to not be alone in theuniversewe something more sapeint. Mars probably supplies nearly as life sustaining an environment as the interior of Antarctica but there are only microbes & lichen there. It took central Africa to evolve human beings.

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DEU

@9percentgroth-you are an Alien, I�m a probability equation. Paul Davis is uncertain Australian. The Enigma of Isadore Ducasse. i.e. the brown paper and string theory.

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GBR

Lacanian :

"His evolving universes idea suggests that the laws of physics are *not* fixed and that we may indeed just happen to be in a universe suitable for life (for now) "

Davies posits much the same idea , except he uses a quantum observer effect to introduce a causal loop between the ultimate concious fate of the universe and its initial state . Hence making the evolution of physical laws necessarily life producing because it is conscious life that picks the laws . At least I think that is his idea . I didn't quite understand it .

Smolin's ideas are interesting , but I'm not sure how they could be tested . Though I have to admit , gradual mutation and no selection as a mechanism for generating complex universes is conceptually quite elegant .


GBR

I am currently about half-way through Marcus Chown's latest book and he covers much the same ground as Davies.

He does, however, produce one hypothesis that is new to me by Stephen Wolfram, who suggests that our mathematical view of the universe is very constraining. He likens it to trying to understand the world on a dark night by looking at the patch of ground illuminated by a street lamp. Wolfram says that the explanation is much simpler than myriad equations that do not agree with each other; it is much more like a four line computer code.

Is anybody familiar with this theory? I am not a mathematician, so I cannot judge its validity.




GBR


"It came as something of a mild consolation when, after going through the different models, Davies admitted that despite his personal preference for the "self-explaining" universe model:
"... they all seem to me to be either ridiculous or hopelessly inadequate ..."
This is an understandable conclusion."

I don't think that is a 'conclusion'. The 'god made it' model is not scientific (glib), the 'no reason' scientific model results in absurdity and the 'multiverse' , in common with the preceding models all require explanations outside of the universe to be explained. Those are inadequate says Davies, and he proposes that explanations for why the universe is the way it is may be found within the universe, not outside of it.

At that point we then have to listen to how Davies says that might work. To stop at the point at which he finishes his explantion as to how and why he would look for explantions within the universe rather than outside of it and call that point a conclusion from which we might launch off into poetry and quoting the quran seems to me a rather pointless excercise which misses the point entirely, for those are the glib and absurd answers which he says are inadequate in the first place.


GBR

PEARL, I wasn't suggesting that an infinite amount of time *would* lead to a universe but that some people *might* think that it wasn't too surpsrising-not that it was an inevitability.

To those who say that we are *just* atoms fail, in my opinion, to take account of the fact of freedom..and if we are just atoms then we are a 'thinking reed' or aware of ourselves being atoms.

I don't know what an explanation *within* the universe would be or mean. Isn't part of the aim of a scientific explanation to get out of subjectivity ? And yet, how can we, who are part of that universe , form a conception of it that at once transcends our own point of view and yet contains the questioning subject at the same time?

I quite like the idea of science launching off into poetry; reminds me of what Simone Weil once said: necessity (the laws of science, say) is the veil of God.

Of course scientists can still look at the world with wonder, but I wonder if something hasn't been lost in a theoretical approach to life and the world?


SWE

SweeneyTodd: 'Another possibility is that the fundamental constants of the universe change with time. So at some point there's a good chance they'll be in a range where our sort of life can exist.'

Paul Davies does discuss this in his book. If I remember correctly, I think he said that more data is still needed before we can conclude that the fundamental constants do change with time.

Lacanian: 'Inayat, for a more interesting idea than the Goldilocks hypothesis, see the work of Lee Smolin. His evolving universes idea suggests that the laws of physics are *not* fixed and that we may indeed just happen to be in a universe suitable for life (for now). But it doesn't always have to be this way...'

Smolin's new book 'The Trouble With Physics' is out in the UK at the end of this month. I think the Guardian's science editor had it as one of his 'looking forward' listings at the end of last year. I might just inflict another blog on you all about it if I find it interesting! http://www.amazon.co.uk/Trouble-Physics-String-Theory-Science/dp/0713997990/sr=1-3/qid=1170692806/ref=sr_1_3/026-5678403-5105231?ie=UTF8&s=books

quirky: 'Seriously, I don't think we can ever know the origin of life and maybe it's better to live in doubt. Certainty about anything is very dangerous, whether it's about science or religion.'

The notion that our knowledge is limited and temporary and that we can perhaps only try to make better and better approximations to what is truth must be ranked as one of the most important contributions of science to our world.

Traianus: 'It's my suspicion that life is absolutely abundant in the universe, and that the Goldilocks Principle is fundamentally unsound.'

Davies also believes that life is abundant throughout the universe. The Goldilocks Enigma is about the universe as a whole, not just the Earth.

WheatFromChaff: See, I couldn't follow your explanation either! I know I must be dumb or a 'blithering idiot' as someone later says...

nabanab: 'I think physicists seem to make the most sense to non physicists when they ( almost ) write prose poems. Maybe we are hardwired to get meaning in this way. Think of anything else well conveyed in layers of poetry to a mass audience?'

Good point. ;-)


USA

What is noteworthy is that of all animate matter only a very tiny minority of humans ever think about the structure and significance of existence--i.e. the expanse and purpose of what humans call the universe. Limitlessness of matter--what is the tiniest portion of matter and what is the volume of the universe--seems to be a major precursor question before the big "why" question.

Of course, most humans never ponder such questions; they are too taken up with plotting the next meal or how to satisfy other organic needs.

But then the big question remains: why the huge waste of energy on the universe? If the laws of physics are efficient then it would certainly have been better to have a mostly empty universe--or just "nothing"--if that's possible.

The idea of a conscious creator it would seem is just childish anthropomorphic vanity--yet that's what a very substantial number of humans subscribe to.

So what shall it be? Stoicism or Epicureanism? Mill's happy pig or a depressed Socrates?


GBR

As Inyat's article shows all the running is being made by scientists, not theologians.

All the religious can do is stand on the sidelines and say "really, is that right? I didn't know that."

But what else can they do? Either their holy texts are meaningful and wrong, or they're hippy-dippy poetry that doesn't mean anything, such as the notion that the sky is solid (it can fall on you after all) and made of seven layers, one of which includes the stars:

http://www.infidels.org/library/modern/denis_giron/islamsci.html


GBR

Ye Heathen's! God made the Universe Father Dan told me.
There's far to many agitaters on this site, but God knows who the Aligator's are! so be careful.


ESP

If only Mr. Bunglawala would read more of the myriad 'popular' science books that are available. You'd have to wonder how he and all the strict adherents to the Abrahamic religions would manage to shoehorn all this 'evidential knowledge'into their sacred books and make it all fit.

I have been reading science books for the last forty years, I barely understand a word of them but I do sense the flavour and they most certainly impart a sense of wonder that might even be called religious. However this has nothing to do with most definitions of the word 'God'.

Mathematics is the language of the universe. Scientists deliver their discoveries to us through hopelessly inadequate metaphors. From what I hope I understand
correctly in my ramblings through biology, genetics, chaos theory, quantum physics etc. etc.is that there is a mental aspect to the universe as fundamental as matter/energy/time; the most glaringly obvious, as noted by other posters - the strong and weak anthropic principles.

No mind - no universe.


ESP

If only Mr. Bunglawala would read more of the myriad 'popular' science books that are available. You'd have to wonder how he and all the strict adherents to the Abrahamic religions would manage to shoehorn all this 'evidential knowledge'into their sacred books and make it all fit.

I have been reading science books for the last forty years, I barely understand a word of them but I do sense the flavour and they most certainly impart a sense of wonder that might even be called religious. However this has nothing to do with most definitions of the word 'God'.

Mathematics is the language of the universe. Scientists deliver their discoveries to us through hopelessly inadequate metaphors. From what I hope I understand
correctly in my ramblings through biology, genetics, chaos theory, quantum physics etc. etc.is that there is a mental aspect to the universe as fundamental as matter/energy/time; the most glaringly obvious, as noted by other posters - the strong and weak anthropic principles.

No mind - no universe.


GBR

kmir - the trouble is that we do not have an infinite amount of time. We now know - thanks largely to Einstein - that the universe had a beginning, and our best estimates are that it began approx. 15 billion years ago. Saying that it was always there simply isn't an option any more. Something caused the universe to come into being - like it or not.

There is not the slightest evidence for any universe other than our own, so there is no point considering the multiverse option.

The God hypothesis is the best we have because God is outside time and space, and only something (or someone) outside time and space can create a universe with these characteristics. Further, only God, being outside time and space, does not require a cause.

The God hypothesis also has the advantage of providing a plausible explanation for the existence of specified, complex information in DNA. The DNA code must have been written by something or someone, i.e. a code, like a novel, requires a writer.

Incidentally, it is far from arrogant to suggest that life is unique to this planet. The chance of life having evolved even once is so astronomical as to be statistically impossible. For it to also have occurred elsewhere in the universe would merely represent further evidence of design.


USA

What is noteworthy is that of all animate matter only a very tiny minority of humans ever think about the structure and significance of existence--i.e. the expanse and purpose of what humans call the universe. Limitlessness of matter--what is the tiniest portion of matter and what is the volume of the universe--seems to be a major precursor question before the big "why" question.

Of course, most humans never ponder such questions; they are too taken up with plotting the next meal or how to satisfy other organic needs.

But then the big question remains: why the huge waste of energy on the universe? If the laws of physics are efficient then it would certainly have been better to have a mostly empty universe--or just "nothing"--if that's possible.

The idea of a conscious creator it would seem is just childish anthropomorphic vanity--yet that's what a very substantial number of humans subscribe to.

So what shall it be? Stoicism or Epicureanism? Mill's happy pig or a depressed Socrates?

Sunday, January 07, 2007

Physics Will Not Achieve a Theory of Everything

Reposted from: http://edge.org/q2007/q07_14.html
my highlights in blue

FRANK WILCZEK
Physicist, MIT; Recipient, 2004 Nobel Prize in Physics; Author, Fantastic Realities

Physics Will Not Achieve a Theory of Everything

I'm optimistic that physics will not achieve a Theory of Everything.

That might seem an odd thing to be optimistic about. Many of my colleagues in physics are inspired by the prospect of achieving a Theory of Everything. Some even claim that they've already got it. (Acknowledging, to be sure, that perhaps a few i's remain to be dotted or a few t's to be crossed.) My advice, dear colleagues: Be careful what you wish for. If you reflect for a moment on what the words actually mean, a Theory of Everything may not appear so attractive. It would imply that the world could no longer surprise us, and had no more to teach us.

I don't buy it. I'm optimistic that the world will continue to surprise us in fascinating and fundamental ways.

Simply writing down the laws or equations is a long way from being able to anticipate their consequences. Few physicists—and no sober ones—seriously expect future work in fundamental physics to exhaust, for example, neuroscience.

A less literal reading of "Theory of Everything" is closer to what physicists who use it mean by it. It's supposed to be a theory, not really of everything, but of "everything fundamental". And here "fundamental" is also being used in an unusual, technical sense. A more precise word here might be "basic" or "irreducible". That is, the physicists' Theory of Everything is supposed to provide all the laws that can't be derived logically, even in principle, from other laws. The structure of DNA surely emerges—in principle—from the equations of the standard model, and I strongly suspect that the possibility of Mind does too. So those phenomena, while they are vastly important and clearly fundamental in the usual sense, aren't fundamental in the technical sense, and elucidating them is not part of a Theory of Everything.

I think we're about to enter a new Golden Age in fundamental physics. The Large Hadron Collider (LHC), which should begin to operate at CERN, near Geneva, starting in summer 2007, will probe the behavior of matter at energies higher than ever accessed before. There is no consensus about what we'll find there. I'm still fond of a calculation that Savas Dimopoulos, Stuart Raby and I did in 1981. We found—speaking roughly—that we could unify the description of fundamental interactions (gauge unification) only within an expanded version of relativity, which includes transformations of spin (supersymmetry). To make that dual unification we had to bring in new particles, which were too heavy to be observed at the time, but ought to be coming into range at the LHC. If they do exist we'll have a new world of phenomena to discover and explore. The astronomical riddle of dark matter could well be found there. Several competing ideas are in play, as well. The point is that whatever happens, experimenters will be making fundamental discoveries that take us by surprise. That would be impossible, if we had a Theory of Everything in the sense just described—that is, of everything fundamental.

In recent months a different, much weaker notion of what a "Theory of Everything" might accomplish has gained ground, largely inspired by developments in string theory. In this concept, the Theory provides a unique set of equations, but those equations that have many solutions, which are realized in different parts of the Universe. One speaks instead of a multiverse, composed of many domains, each forming a universe in itself, each with its own distinctive laws. Now even the fundamental—i.e., basic, irreducible—laws are beyond the power of the Theory to supply, since they vary from universe to universe. At this point the contrast between the grandeur of the words "Theory of Everything" and the meager information delivered becomes grotesque.

The glamour of the quest for a Theory of Everything, or a Final Theory, harks back Einstein's long quest for his version, a Unified Field Theory. Lest we forget, that quest was fruitless. During his great creative period, Einstein produced marvelous theories of particular things: Brownian motion, the photoelectric effect, the electrodynamics of moving bodies, the equality of inertial and gravitational mass. I take inspiration from the early Einstein, the creative opportunist who consulted Nature, rather than the later "all-or-nothing" romantic who tried (and failed) to dictate to Her. I'm optimistic that She'll continue to surprise me, and my successors, for a long time.

Saturday, January 06, 2007

What Lies Beyond Our Cosmic Horizon?

reposted from Edge.org. Chris Street highlights/edits in bold.

ALEXANDER VILENKIN

Cosmologist, Tufts University; Author, Many Worlds In One

What Lies Beyond Our Cosmic Horizon?

There is a limit to how far we can see into the universe. Our cosmic horizon is set by the distance traveled by light since the big bang. More distant objects cannot be observed, because their light has not yet reached the Earth. But of course the universe does not end at the horizon, and the question is what lies beyond. Is it more of the same — more galaxies, more stars, or could it be that remote parts of the universe are very different from what we see around here? I am optimistic that we will be able to answer this question and understand the structure of the universe as a whole, even though we can observe only a small part of it.

Until recently cosmologists made the simplest assumption — that the universe is homogeneous, i.e. looks everywhere more or less the same. (It was glorified under the name of "Cosmological Principle", but it was still only an assumption.) Now, recent developments in cosmology and particle physics have led to a drastic revision of this view and to a heated debate about the future of our science. According to the new worldview, most of the universe is in the state of explosive, accelerated expansion, called "inflation". In our local region, inflation ended 14 billion years ago, and the energy that drove the expansion went to ignite a hot fireball of elementary particles. This is what we call the big bang. Other big bangs constantly go off in remote parts of the universe, producing regions with diverse properties. Some of these regions are similar to ours, while others are very different.

The properties of any given region are determined by the quantities we call "constants of nature". These include particle masses, Newton's constant, which controls the strength of gravity, and so on. We do not know why the constants in our region have their observed values. Some physicists believe that these values are unique and will eventually be derived from some fundamental theory. However, string theory, which is at present our best candidate for the fundamental theory of nature, suggests that the constants can take a wide range of possible values. Regions of all possible types are then produced in the course of eternal inflation. This picture of the universe, or multiverse, as it is called, explains the long-standing mystery of why the constants of nature appear to be fine-tuned for the emergence of life. The reason is that life evolves only in those rare regions where the constants happen to yield suitable chemistry and physics. The values of the constants in our own region are then determined partly by chance and partly by how suitable they are for the evolution of life.

Many of my colleagues find this multiverse picture very alarming. Since all those regions with different values of the constants are beyond our horizon, how can we verify that they really exist? Is this science — to talk about things that can never be observed? In my view, it is science, and there are good reasons to be optimistic about the new picture. If the constants vary from one part of the universe to another, their local values cannot be predicted with certainty, but we can still make statistical predictions. We can try to predict what values of the constants are most likely to be observed. One such prediction, that the vacuum should have a small nonzero energy, has already been confirmed. We have only started along this path, and formidable challenges lie ahead. I believe, however, that what we are facing now is not the end of cosmology, as some people fear, but the beginning of a new era — the exploration of the multiverse.

Saturday, December 30, 2006

Parallel universes may be discovered in 50 years

Max Tegmark forecasts the future

  • 18 November 2006

In 2056, I think you'll be able to buy a T-shirt on which are printed equations describing the unified physical laws of our universe. All the laws we have discovered so far will be derivable from these equations.

We will have confirmed beyond doubt, through observation, that what we now call the big bang wasn't the beginning of everything, merely the time when our part of space stopped undergoing an explosive stretching called inflation. We will have understood the physics of inflation well enough to know that inflation continues forever in some faraway places, and that in other places where it has ended and allowed life to evolve, the T-shirts on sale mostly have different equations.

The existence of such "parallel universes" will be no more controversial than the existence of other galaxies - then called "island universes" - was 100 years ago. This idea was controversial until Edwin Hubble settled it in 1925.

Billions of Universes?

Martin Rees forecasts the future

  • 18 November 2006

I hope that in 50 years we will know the answer to this challenging question: are the laws of physics unique and was our big bang the only one? Theoretical horizons have recently expanded astonishingly. According to some speculations the number of distinct varieties of space - each the arena for a universe with its own laws - could exceed the total number of atoms in all the galaxies we see. Most space-times would be sterile or stillborn, but among this cornucopia there could still be immense numbers that allow big bangs that "fly" - allowing the emergence of the rich complexity that leads to atoms, stars, planets, biospheres and brains able to contemplate their origins. So do we live in the aftermath of one big bang among many, just as our solar system is merely one of many planetary systems in our galaxy?