Gravity and the Multi-verse?

[Beerina]

Parsimmony suggests they must be all of the same stuff somehow, but that doesn't necessarily need to be the case. Gravity and the other forces (as a lump) could be two completely unrelated phisical phenomena that happen to interact in such a way as to create/overlap (in) this universe. Physicists should probably keep that in the back of their minds.

 

[Wolfman]

No one said string theory is correct simply because it can't be proven false. Andyandy said that we can't say it's false because we can't prove it's false. There's a difference.

So, Roboramma, you are arguing that any theory that I can't prove false (existence of god, psychic powers, etc.) is a viable, non-woo theory? Sorry, I don't agree with your argument here at all.

String theory has a vast amount of mathematics behind it. If you take those mathematics and extrapolate "how would matter act in such-and-such a scenario", you find that it describes the way our universe actually does act. In science, a theoretical model that is able to accurately predict observable behavior is considered to be a viable theory; not necessarily considered to be 'proven' or 'fact', but certainly worthy of greater experimentation. The more predictions we have that match up with observed reality, the more we can consider it as a realistic possibility. The more predictions we have that do not match up with observed reality, the more we can consider it to be false.

String theory doesn't have much in the way of actual experiments that we can do to 'prove' the existence of strings. But when you work through the mathematics, they not only predict behavior that is identical to what we observe, but also provides explanations for some behaviors that we are hard-pressed to explain using any other theory.

That is very, very different from 'woo' theories that take a small number of observable phenomena that seem to support their ideas, but ignore anything to the contrary. There is absolutely no observable phenomena in our universe that contradicts string theory; and every mathematical prediction arising from string theory (at least any I am aware of) have given results that mirror observed phenomena. Perhaps there are those here who are aware of predictions arising from string theory that are contrary to what we actually observe, if so, please list them.

 

[CapelDodger]

Brian Greene discussed the idea that gravity might be so weak because its action occurs across different "brane worlds" near the end of The Fabric of the Cosmos. It's not woo; it's just speculative. It appears that the idea can be applied using other than string theory, too; being as how we see it being discussed here in the context of the Many Worlds interpretation of the Standard Model. So I think that suggesting it's woo is either premature, or disingenuous.

I first heard of the idea years ago (probably in SciAm) and thought it intriguing. I'm a science dilettante so I've never followed it up, but the question that struck me was if mass here has an influence there the influence should be detectable there, as should the influence of mass there be detectable here. Is there any sign of it? What would theoretically be a sign of it?

 

[Roboramma]

So, Roboramma, you are arguing that any theory that I can't prove false (existence of god, psychic powers, etc.) is a viable, non-woo theory? Sorry, I don't agree with your argument here at all.

Good, because that's not my argument. I'm arguing that the fact that we can't (yet) prove it false isn't reason enough to throw it away.
As I said, it doesn't show that it's true, obviously. This by itself certainly isn't enough to say that it requires further investigation, either.
But to say, "it's not presently falsifiable, therefore it's false" is silly.

Again, and I think I said this in my last post - the fact that we can't prove it false doesn't make it false. The fact that there is no evidence for something makes it unlikely, but that alone doesn't mean that it's not worth investigation. Sometimes there's no evidence simply because we haven't yet looked.
Some things, though, not only is there no evidence, but there's a lack of evidence exactly where we would expect to find it. Other things, though we might not expect evidence, we also have no reason to believe that they are true. I don't think either of these things are true of string theory.

Again, I don't know that string theory is all that valuable, but I don't think it's fair to call it woo just becuase we don't yet know how to falsify it.

String theory has a vast amount of mathematics behind it. If you take those mathematics and extrapolate "how would matter act in such-and-such a scenario", you find that it describes the way our universe actually does act. In science, a theoretical model that is able to accurately predict observable behavior is considered to be a viable theory; not necessarily considered to be 'proven' or 'fact', but certainly worthy of greater experimentation.

The problem here, at least as far as my very limited knowledge of string theory does, is that string theory was constructed based upon that data. We need new data to actually test it.

The more predictions we have that match up with observed reality, the more we can consider it as a realistic possibility. The more predictions we have that do not match up with observed reality, the more we can consider it to be false.

Of course. That's sort of my point. String theory may or may not be accurate, or a good theory, the only way to find out is to test it. The problem that Fnord pointed out is that we don't know how to test it right now. He suggests that this is reason enough to discard it. But there are reasons to think that it's promising, and those reasons may be enough to suggest that we continue to look for ways to test it.

String theory doesn't have much in the way of actual experiments that we can do to 'prove' the existence of strings. But when you work through the mathematics, they not only predict behavior that is identical to what we observe, but also provides explanations for some behaviors that we are hard-pressed to explain using any other theory.

Which sort of supports the point I made that it isn't woo, right?
My point wasn't that because it isn't falsifiable we should give it weight. My point was that not being falsifiable doesn't mean it's wrong - we need other things to determine that. Particularly the fact that we may find ways to test it in the future.

That is very, very different from 'woo' theories that take a small number of observable phenomena that seem to support their ideas, but ignore anything to the contrary.

I agree completely.

There is absolutely no observable phenomena in our universe that contradicts string theory;

By saying this you're basically saying that we can't show that it's false. Again, that's the point I was making - the fact that we can't show it's false doesn't mean it's false!

Let me try to simplify my logic:
Call x all things that are false but which we can't prove to be false.
Call y all things that we can't prove to be false.
y > x.
Because of this, saying that something is y is not sufficient to say that it is also x. We need more information to determine that.

 

[Wolfman]

I agree completely.
By saying this you're basically saying that we can't show that it's false. Again, that's the point I was making - the fact that we can't show it's false doesn't mean it's false!

Let me try to simplify my logic:
Call x all things that are false but which we can't prove to be false.
Call y all things that we can't prove to be false.
y > x.
Because of this, saying that something is y is not sufficient to say that it is also x. We need more information to determine that.

I think we may be trying to say the same thing...the problem for me is that with your definition, a lot of stuff that I consider to be "woo" could be argued not to be "woo", because we can't "prove" it false.

In my opinion, this has nothing to do with our ability to demonstrate that it is false or not. If we could demonstrate absolutely that it was false, that would of course be great. But a theory does not qualify as either 'woo' or 'not woo' simply because we can't prove it is false.

I'd argue that a 'woo' theory is one for which there is either no evidence, or for which a small portion of evidence supports it while a much larger portion of evidence discredits it. The "woo" supporter relies either on gut feelings, or on ignoring all evidence contrary to their theory (or, occasionally, on complete delusions, such as voices in their heads).

In the case of string theory, there is actually a tremendous amount of mathematics that supports it; while there is no evidence to indicate that it is wrong. That doesn't mean that it is, in fact, the correct model; but it moves it safely out of 'woo' territory. I'm no mathematician, and I'm sure others here can provide more solid examples, but there have been cases in which the mathematics of string theory predicted certain sub-atomic phenomena which had not previously been observed, or for which there was no explanation; when subsequently tested, the predicted phenemona were observed to take place (and this is one of the reasons for building the super-collider mentioned in the first article, to further test some of those predictions).

15-20 years ago, string theory was considered 'woo' by the majority of the physics community, because there was very little to support it, and it seemed to violate common sense...and, initially, they did take a few wrong directions in pursuing it.

String theory's status has not changed simply because someone hasn't proven it's false; it has changed because of a huge amount of mathematics and theoretical physics which demonstrates that it provides a consistently accurate model of our universe, and how our universe functions.

 

[Apathia]

Does this mean that any as yet unproven bit of Theoretical Physics or Cosmology is woo-woo? OK, is it woo-woo because it's still lacking decisive evidence after so many years? Are people who continue to invest research time and money in Superstring Theory, M-Theory, and other variations of Brane and Extradimensional theories, woos?

According to many of these 'woos,' decisive evidence will come in experiments with the Large Hadron Collider, or they hope so. Is Theoretical Physics and Cosmology woo-woo, especially when it posits stuff we don't have the technology to call yet?

Should these people be given research grants to put forth patently woo-woo ideas such as "hidden diminsions," gravitons, fantisies of Grand Unified Theories, speculations about conditions at the Big Bang and the formation of Galaxies, and all kinds of other wild, inflamed imaginings?

 

[Wolfman]

Should these people be given research grants to put forth patently woo-woo ideas such as "hidden diminsions," gravitons, fantisies of Grand Unified Theories, speculations about conditions at the Big Bang and the formation of Galaxies, and all kinds of other wild, inflamed imaginings?

I'm curious, Hyparxis...is your contention that all these ideas are "woo-woo" based on actual evidence? Or just on your inability to understand them?

Let me give an example -- the existence of atoms was predicted long before we had the technology to prove they existed. But, despite our inability to prove it by direct observation, scientists were able to make predictions -- "If atoms exist, then we can predict the following phenomena" -- that were confirmed by experiment.

Please read my definition above of "woo" and "non-woo". "Woo" would be those theories that have no evidence whatsoever, or in which a small proportion of evidence supports it, but a larger proportion discredits it (but is ignored by the woo-sayers). "Non-woo" would be theories in which the preponderance of evidence supports the theory.

Now, the thing is, in our current understanding of the universe, based on current (by this I mean, theories predating things like string theory) theories, there are certain phenomenon which we cannot explain. And current models are entirely incapable of giving us a "Unified Theory of Everything" (to explain how all the different forces in the universe act/interact).

These new theories -- for all that you call them "woo" -- do not in any way violate what we observe in the world around us. The mathematical models they are built one match almost perfectly with the actual world we observe, both on atomic and subatomic levels. In addition, they show much greater promise of enabling us to unify all of nature's forces, something that is impossible with 'conventional' theories.

I am not aware of any evidence that contradicts the theories or predictions of these fields. If you know of some, please feel free to share it with us.

To summarize:

• a theory that does not contradict any observed/measured effect in our universe
• a theory that explains phenomena in our universe better than conventional models
• a theory that enables us to unite different forces that are impossible to unite under conventional models

I don't see how this can be categorized as "woo". Granted, most of it requires such exotic mathematics, and drastically different views of reality than our 'intuition' would indicate is 'logical', that to the average joe it'll appear like a bunch of hocum that deserves to be relegated to the loony bin. But inability to understand it does not mean that it is wrong.

If you want to demonstrate that it deserves the designation of being "woo", then rather than simply dismissing it, how about presenting actual evidence? Showing us how these theories are actually wrong? How they are less able to explain our universe than the conventional models we accept as "true" now?

From Einstein to Hawking, the world has been introduced to theories that at first seemed wild and crazy -- but which have subsequently come to be accepted as fundamental truths. Here we have new theories which explain our universe even better than those theories do, without contradicting any observed phenomena, yet we should just call them "woo"?

I'm not saying that these theories are the correct models; but it certainly appears that they are at least leading us in a direction that leads to a greater understanding of the fundamentals of how our universe works than anything else currently on the table.

And that's why I'd say that funding such research is very, very different from funding "woo".

 

[Orphia Nay]

I think all of us, Hyparxis, Wolfman and I included, agree with Roboramma's comment that:

... I don't think it's fair to call it woo just because we don't yet know how to falsify it.

Except for the "free lunch" multiverse theory, yes? Although I think that's been falsified. Sorry if I'm a bit out of my depth here, but I find this fascinating all the same.

 

[Apathia]

Thank you, Wolfman! You made the line very clear on that.
Of course the Theoretical Physicists who advance the frontiers of Science are more intelligent and imaginative than me. And it would be a silly prejudice for me or anyone else to chalk them up as 'woos,' because we aren't yet in a position where we can get deciding evidence.

 

[Apathia]

Yes, what Orphia Nay said.

Though I hadn't heard that Multiverse ideas were dead yet. Does that include thories that posit more than three spatial dimensions?

 

[Orphia Nay]

Cheers, Hyparxis.

I found this thread over at Bad Astronomy that touches upon some of the theories of a multiverse.

My references to the "free lunch" theory might be a bit confusing. Firstly, it seems the Big Bang theory is opposed by some who say it did not evolve out of nothing, and "there's no such thing as a free lunch", so the universe must be cyclic - expanding then contracting cyclically.

But I was referring to the possibly woo theory that black holes cause singularities that create universes in another dimension. I coined a phrase years ago (but others seem to have thought of it too): "The Big Banging". But I guess we don't know enough to say whether there really is no "lunch" in a black hole.

 

[Wolfman]

I think all of us, Hyparxis, Wolfman and I included, agree with Roboramma's comment that:

Except for the "free lunch" multiverse theory, yes? Although I think that's been falsified. Sorry if I'm a bit out of my depth here, but I find this fascinating all the same.

Orph,

I've done some follow-up research on the whole 'multiverse' thing. Initially, the idea of alternate universes started with science fiction, a convenient plot device to posit alternate realities, alternate timelines, etc.

When scientists first started seriously exploring the idea of alternate universes, some of them pursued it in rather non-productive directions; and popular media descriptions inevitably relied on sci-fi stereotypes, which further muddled the waters, and resulted in a lot of woos getting involved and coming up with their own ideas.

However, from what I can find now, many scientists -- including many of the top theoretical physicists -- take this idea very seriously now. One of the questions about our own universe has been the question of why it has the specific laws it does...there is actually nothing innate that anyone can find that dictates our universe must be the way it is. Many, many other types of universe, with different laws, are very possible.

Of course, the anthropic principle comes into play here, kind of like the 'tree falling in a forest' anecdote; if a universe has laws that preclude the existence/development of life within that universe, does that universe actually exist? Or does it matter?

Now, if ours is the 'only' universe, the odds that it would have developed in the way it has are extremely low; but if we posit a multitude of different universes, suddenly it becomes almost certain that at least a few of them would develop with laws similar to or the same as our own.

On a theoretical level, this is fascinating to me -- are there other universes with the same laws as ours, and would it be possible to travel to them? Or would it be possible for life to develop in universes with different laws, and what would life in those universes be like?

But on a practical level, at least one branch of theoretical physics now posits the theory that our universe may interact with other universes in some ways; not only in the example of gravity that I mentioned earlier, but also in explaining things such as interference patterns in double slit experiments that use only one photon of light at a time (in these experiments, only one photon is released at a time, yet it still forms an interference pattern, which should not be possible unless it is interacting with other photons).

It is this aspect that has led some woo types into concepts of "free energy", where they tap into energy sources from other universes and bring it into this universe, thereby effectively producing more energy than was put into it. Nothing in current physics models supports such an idea (interaction between different universes is very different from sharing or channeling energy from different universes).

I'm not sure if the existence of other universes, if proven, would have any practical impact on our lives (ie. that we'd actually be able to do anything with that knowledge); but much of man's endeavor seems to be to understand the 'how' and 'why', even if after answering those questions it turns out we can't do much with that information.

 

[andyandy]

This is known in all fields of inquiry as the "Argument from Ignorance." It is a fallacy of reason to claim that something is true only because it has not been proven false.
.

-Fnord of Dyscordia-

To say that "because something has not been proved true does not make it false" is not the same as to say that "something is true because it has not been proven false." These statements are not equivilent.

 

[Wolfman]

To say that "because something has not been proved true does not make it false" is not the same as to say that "something is true because it has not been proven false." These statements are not equivilent.

*a lightbulb flashes above my head*

If this was the argument that roboramma was making earlier, and I misread/misunderstood it, I apologize; I agree completely with this statement.

 

[andyandy]

I think you have completely misunderstood the point of the anthropic principle. If any of those necessary conditions were not true, then either we wouldn't be here to note it, or "we" would be very different creatures in a very different time and place. In the cosmic scheme of things, our existence is inconsequential. Ten billion years ago our sun didn't exist, and neither did we. Do you think conditions looked so finely tuned for life back then? Indeed, the way our universe is ordered at the moment is inconsequential cosmically as well.

Our universe only looks finely tuned (which is of course a concept from Intelligent Design theory) because we are already here within it and looking back at it. If we didn't exist in it, but could somehow look at it objectively from outside it, it wouldn't look nearly so interesting without life. Sure, some really spectacular stuff goes on as a result of activity in and around stars, but another universe with different physical laws might be more or less spectacular. In any case, we'll never know because we cannot.

AS

i appreciate this point, but don't believe an anthropocentric argument for human sentient existence is the one which i was making. We take as a fact that this universe exists - we know it does. The probability of this universe existing is in one very real respect 1. All well and good. If we subscribe to the single-verse therory then this universe is the only one that exists - and it just so happens that sentient beings such as ourselves are aware of that existence. Again this is fine.
The problem comes when we try to model the universal expansion of the big bang using current standard models for elementary particles and for cosmology. The best fit models introduce a great number of parameters with which to determine universal expansion (or indeed non-expansion). Attempts to unify these parameters have so far failed - indeed, string theory has seemingly just introduced even more. So we are left with the following explanations, either the standard models for cosmology and elementary particle phyiscs are incorrect, the models are correct but there is an underlying unifying theory which links the seemingly unrelated parameters together, the models are correct and our universe exists as it does solely as a result of a vanishingly small probabilistic outcome, the models are correct, and the vanishingly small probabilistic outcome is accounted for through a tremendous repetition of initial conditions. Of all those explanations, whilst all are rather unsatisfactory, the least unsatisfactory one, based on that which we currently know, would appear to be the tremendous repetition of inital conditions.

 

[andyandy]

There is absolutely no observable phenomena in our universe that contradicts string theory; and every mathematical prediction arising from string theory (at least any I am aware of) have given results that mirror observed phenomena. Perhaps there are those here who are aware of predictions arising from string theory that are contrary to what we actually observe, if so, please list them.

I think a prediction of the cosmological constant was out by a factor of 10^50*
- that's a pretty big error

But the main criticism of string theory seems to be the number of predictions it makes - put simply if you make enough predictions, then no experimental data can falsify your theory - because it's contained within that greater predictive framework. Distinct theories based on string theory to explain a four dimensional macroscopic world with a small positive vacuum energy have been estimated at an order of between 10^100 to 10^500.
If you want to read a critique of string theory (and discussion of anthropic principles), this is a really interesting article by Smolin (well, more like chapter..)

http://arxiv.org/PS_cache/hep-th/pdf/0407/0407213.pdf
Or
http://arxiv.org/abs/hep-th/0407213

I'm not sure i agree with all his arguments - but he does make some valid points....



*Peter Woit "not even wrong...."

 

[Cuddles]

I really don't understand why people have such a problem with string theory (or really M-theory, string theory is obsolete) and label it woo. It is clearly not woo. Anyone who says it does not make testable predictions is wrong. Anyone who says it is not falsifiable is wrong. Anyone who says there is no evidence for it is wrong. M-theory is a perfectly good hypothesis (or set of hypotheses to be more accurate). For all the observed data we have, it predicts exactly what we see, as does the standard model, they are both equally valid. The reason we have not thrown out the standard model, even though we are certain that it is wrong, is that it is more established and simpler, so in the abscence of any evidence to tell them apart it is the more logical choice.

Anyone who knows anything at all about particle physics should know that the main purpose of building bigger accelerators is in fact to get evidence for the various different theries and hypotheses around so that we can tell them apart. String theory, M-theory, supersymmetry and all the rest make very solid predictions about the masses, and even the existence, of many different particles. The LHC should be able to start eliminating theories, although it is very likely that even higher energies will be required later. This is not woo, this is science. The whole point of science is to test your ideas, and this is exactly what we are doing.

 

[Wolfman]

I really don't understand why people have such a problem with string theory (or really M-theory, string theory is obsolete) and label it woo. It is clearly not woo.

While I personally agree with you, I think that the reasons why others see it as 'woo' are fairly simple. First, the mathematics involved are on a level that very few people in the entire world can truly understand them; for the majority of us laypeople, we must rely on illustrations and approximations that at the best give only a partial understanding of the underlying structure.

Second, most of this stuff seems entirely counter-intuitive. It violates the most basic rules of 'reality' as we experience them. How can a radioactive particle exist and not exist at the same time? How can the universe have 7, or 8, or 9 different dimensions? The behavior of matter at quantum levels seems completely bizarre...in fact, I know of a number of woo theories that would seem to be more logical or make more sense than some of the theories proposed by theoretical physicists.

To the lay person, it often seems like these people are just pulling explanations out of hat (and a rather bizarre hat at that); like they just come up with bizarre ideas, and then try to twist the math to fit their theories. In fact, while it is sometimes true that they act in this way, in many more cases it is the math which has come first, to produce unexpected results...and the new theories have come about in an effort to explain the math.

If we some day have a theory that can consistently explain all the phenomena in our universe, and in which the math is consistent and reliable, we'll be able to feel reasonably confident that we've found 'the answer'. But we aren't even close to that now. Instead, we have a number of different models and theoretical constructs that all address certain aspects of the puzzle, but none of which have yet proven to give and unequivocal answer.

Continuing to explore and develop those different theories is very important, even though it is likely that some of them will ultimately prove to be wrong. That's how science works. No, string theory (or M-theory) may ultimately prove not to be 'the answer'...but they are a step in the right direction.

 

[andyandy]

I really don't understand why people have such a problem with string theory (or really M-theory, string theory is obsolete) and label it woo. It is clearly not woo. Anyone who says it does not make testable predictions is wrong. Anyone who says it is not falsifiable is wrong. Anyone who says there is no evidence for it is wrong. .

i think the problem is over "woo" - any proper scientific research does not qualify as "woo" - at least in my understanding of the term (i've yet to see a dictionary definition ) and so i agree completely that string theory or M-theory or a theory on gravity dilution does not qualify as such. There are justifiable criticisms that can be raised - such as the incredibly large predictive framework string (/M) theory operates in. And ultimately there remains the possibility that some derivations from M-theory such as a multiverse explanation for cosmic origins may prove to be unfalsifiable - if those universes are disjoint with no interaction with our own then it's rather difficult to prove they don't exist. But having said that is seems that plenty of physicists are confident that a string - or brane - based approach offers significant scientific advances....so who am i to argue? I look forward with great interest to the LHC experiments.....

 

[Roboramma]

*a lightbulb flashes above my head*

If this was the argument that roboramma was making earlier, and I misread/misunderstood it, I apologize; I agree completely with this statement.

Ah.. yes. Sometimes I write far too much for my own good when one sentence would have been much clearer. Hm, I'm doing it again.