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Can String Theory Accommodate Inflation?
David Shiga writes "String theory is the leading contender for a "theory of everything" that could unite all the forces of physics. But a recent study suggests that it may be more difficult than scientists had hoped to square string theory with inflation — the widely accepted notion that the early universe had a period of especially rapid expansion. Some say this could even lead to the abandonment of either string theory or inflation, though no one is ruling out a possible resolution yet."
It is said that papers in string theory are published at a rate greater than the speed of light. This, however, is not problematic since no information is being transmitted.
I don't think ANYTHING can accomodate inflation.
Just disrupt the deflector shield with a tachyon burst.
Does string theory incorporate the inflation of meatballs and saucy noodles (i.e. strings) due to FSM?
Sure.
As central governments print more and more strings, the strings currently in circulation are devalued.
"String theory is the leading contender for a 'theory of everything' that could unite all the forces of physics. [citation needed]"
Yet another post validating this argument
(yeah, yeah, it's old. So sue me)
String theory's inability to accommodate inflation has been driving me nuts ever since we converted everything to type string. What a mistake that was. String theory needs some more time in the oven before it's going to be universally acceptable.
If the Fed cuts interest rates next week.
We're talking the physics of balloons here, are we?
String theory should be discarded. It's a fanciful religion that explains nothing, but creates a lot of stuff that needs explaining.
When any Big Bang type of theory is mentioned, I sometimes wonder why alternative theories, like the Electric Universe, are never mentioned, as though there is only one way to try to explain cosmological phenomenon. I would really like to see some experiments or at least some solid reasoning (instead of the usual approach, which is dismissal) to attempt to falsify some of the claims made here or here or here.
While I am not entirely certain that the Electric Universe has The Truth either (nor do I think it's a good idea to ever fully believe that this is the case), I too am tired of hearing about the "reality" of mathematical entities that have never been directly observed, and of the tendency to just insert dark matter wherever it's needed, after the fact (as opposed to predicting its presence and location by theory), when it is found that our currently understanding otherwise fails to describe the objects we are seeing. I do agree with Wal Thornhill that cosmology is beginning to resemble the Ptolemaic epicycles.
It's also a shame that (at least in the USA) the funding system has made science another self-reinforcing status quo just like the political system, in that no one who is willing to change things and try a totally different approach has any chance of receiving the funding and support that's necessary to get off the ground.
It is a miracle that curiosity survives formal education. - Einstein
grrr!
Brazil needs to know... and they will be in a conundrum!
Strings or inflation???
What a choice!
In the free world the media isn't government run; the government is media run.
At first I thought this was the Bush Administrations latest "plan" on balancing the budget. "...We need to unify the Five Forces of economics, ....and take the fight to Al-Qaeda."
Ok so the Universe came into being with rapid inflation, during the first 0.001 seconds or whatever it was. Then things settled down to all this matter getting itself organised into hydrogen clouds, which formed starts, some of which were super massive and only existed for 100 million years, before blowing themselves to bits, thus creating second generation stars (like Sol) and the stuff of heavier and various other elements (which makes up most of the planets and debris whizzing around Sol), but many stars actually collapse into black holes, or suck up so many other stars they're crushed by their own density and gravity to the point where neutrons are accellerating towards the cores and and emitting radiation bursts (converting matter to energy) until the black holes cease to exist (all this happening in an apparent timeframe which doesn't appear to support some of the physics and estimates of the universe's age. So anyway, if all this matter is turning into energy, why didn't it just do that initially rather than go through this labourious process of creating stars, galaxies, nebulae, etc?
space is big, space is dark, it's hard to find, a place to park. Burma Shave - from Workbench lander
A feeling of having made the same mistake before: Deja Foobar
"String theory is the leading contender for a "theory of everything" that could unite all the forces of physics"
No, it isn't. It makes no verifiable or falsifiable claims, and therefore isn't science.
Solve it like any government would handle an inflation problem...
Print more strings!
Boot Windows, Linux, and ESX over the network for free.
by M-theory. My understanding is that there are 5 different versions of 10-dimensional string theory that can be generalized to 11-dimensional M-brane theory. Not sure about the inflation thing though, I just wanted to throw in the fact that you are talking about an old theory.
If all the little strings are broken, it's no wonder the universe is flying apart!
no one is ruling out a possible resolution yet.
Ah-hem, I am. Please let the record reflect that I was the first to do so.
done. wake me up when there are more scientific milestones up for grabs.
ôó
Admittedly, there is an active and very loud group which has been theorizing that string theory will - at some point in the future - provide a grand unified theory of physics that is testable.
But there is a large and growing group of Ph.D.s who disagree, and believe that string theory is an evolutionary dead end in theoretical physics.
It is remarkable that now they're trying to push their theories into other spheres, when their core concepts are, as yet, unproven.
[caveat - I know this is controversial, in that many faculty and senior faculty in Physics are string theory proponents, but someone needed to point this out]
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String theory is the leading contender for a "theory of everything"
Actually, not it's not. For this to be the case, it would have to predict something that is experimentally verifiable. Which has yet to be the case. All it is now is some really messy math. And even that's giving it something b/c most of it is the typical hand-wavy (read: non-rigorous) "math".
Quite frankly, the only good thing that I see here is that there might be an end to String Theory a.k.a. the "theory" that sucks up most of the money for research even though more than 3 DECADES have gone by without /one/ bloody experimentally verifiable prediction. Perhaps after this is all said and done with, we can spend some money on some actually *promising* areas of research.
String theory isn't science, but it isn't religion either. It's math. Someday it may become science.
Damning string theory is a bit like damning Reiman Calculus was in the 1890's. It was of no existing use. Eventually, though, Einstein found a use for it. That may happen with string theory. Or, of course, it may not.
It is interesting that the math can be mapped onto what is known about the universe. That makes it interesting. But it can't be tested, only particular mappings can be tested. So it's math rather than physics.
I think we've pushed this "anyone can grow up to be president" thing too far.
Dark matter is certainly a bizarre hypothesis, and the question you ask is natural - couldn't we just be wrong about gravity? It's somewhat easier to believe that Einstein's general relativity is modified than that the universe is filled with so much mysterious, unseen "stuff". This is the basic idea behind MOND (MOdified Newtonian Dynamics) theories, which has received a good bit of thought among physicists.
MOND doesn't look like the right solution, however. The last 2 or 3 decades have provided an enormous amount of observational data about the structure of the universe (large scale structure, galactic dynamics, gravitational lensing, light element abundances, the cosmic microwave background...), all of which is basically consistent with the simplest dark matter model ("cold dark matter") and inconsistent with any modified gravity theory. We don't need to imagine any particularly exotic properties to the dark matter, it just needs to be something that doesn't interact with electromagnetic forces (just like a neutrino only much heavier). Even very complicated MOND models fail to match observations, however (unless you add in a bunch of dark matter anyway).
Perhaps the most striking example is provided by observations of the Bullet Cluster last year. Basically we've found a pair of colliding galaxy clusters where the collision has separated the dark matter from the ordinary matter somewhat. Skipping over the details, this provides dramatic evidence that dark matter is real "stuff" - in essentially any modified gravity theory without dark matter, the gravitational forces still have to be coming from the same place as the visible matter! This is a very general argument, and observations like this have more or less put the nail in the coffin of MOND theories.
Astrophysicists are almost universally convinced at this point that something like dark matter exists. We're starting to map its distribution in detail throughout the universe, and the next major challenge will be determining its makeup - either by production in an accelerator or detection in dedicated experiments.
If it can't be tested, it's not science...it's pseudoscience.
String theory is the sort of intellectual game normally played by religions. There's always a part which can never be tested or disproved and that's where you'll end up if you start a "debate". An impasse is the best you can ever achieve if you try.
No sig today...
They'll just add 5 more dimensions.
___
If you think big enough, you'll never have to do it.
Inflation theory sounds more made up. I don't know anything of course so I'm just talking from my ass, but inflation theory describes a single event happened in the distant past, base on some observations and some theories - the question is, what theories? We don't have a good theory of universe yet.
String theory doesn't need to be consistent with the inflation theory. It only has to give a good explanations of current observables. If it does that, it can infer whatever past event in its own framework. But then I heard that it can explain any imaginable universe, well...
God has a sense of humor. Either human live with stupid theories with many arbitrary variables, and with an elegant theory with many arbitrary equations.
What? What other spheres? In order to be a grand unified theory, it must account for inflation, or either: String Theory is wrong or There is no inflation.
Your 'large and growing group of Ph.D.s' aside, it has the best promise of being a method to quantize gravity. There are other methods that should be researched as well, loop quantum gravity springs to mind.
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Much promise, but few deliverables.
I predict in ten years we'll hear much more about how string theory will be proven in the future, with measureable repeatable observations.
But never today. Always the future.
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Not being falsifiable is a strong indicator, but that doesn't mean it is incorrect, or pseudo science. Scientific method is being used. It correlates with what we see, just like the theory of gravity in it's infancy. I use that example, not to compare it to gravity, only to explain there is often a period of time before an observation is put to a falsifiable test.
I am always glad to see people looking our for pseudoscience, but it does need to be tempered with thought.
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Admittedly, there is an active and very loud group which has been theorizing that string theory will - at some point in the future - provide a grand unified theory of physics that is testable.
If there is indeed a "theory of everything," it may be so far outside the range of our current intellect that the complete development of the theory could take centuries. If we are willing to throw away anything just because it hasn't made a new prediction within 30 years, we might be dooming ourselves to NEVER figure it out.
Inflation was introduced because the presumptive model of the Big Bang says that the universe sprang from an infinitesimally small point. At some time later, the expansion rate of the universe is thought to have changed. This change in expansion rate (inflation) was required by the assumption about the point-source of the Big Bang, working backwards from what we see around us today.
But what if the Big Bang was not a point source?
If the universe (the one that we see and experience in our daily lives, anyway) was created when two branes slapped together, there's no reason to think that that had to take place within a single infinitesimal point. If this contact took place over a larger region of space, the diameter of a single hydrogen atom, for example, then "inflation" isn't necessary.
So, replace Big Bang with Big Slap, and get rid of inflation.
The man who does not read good books has no advantage over the man who cannot read them. - Mark Twain
when you said :"I'm just talking from my ass,"
God is Pseudoscience.
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One of the sharpest critiques of string theory is that it isn't really one theory -- it's many, many theories (something like 10^500), depending on how the hidden dimensions are wrapped up. It looks like this study showed that a certain flavor of string theory (IIA) might not be able to accommodate inflation -- but not to worry, the string theorists say, there are plenty of other flavors of string theory that might indeed allow inflation after all! But therein lies the problem: no matter how an experiment turns out, one can cook up a version of string theory that agrees with it! What we really need is a meta-theory (M-theory?) that tells us *which* string theory to use, but so far it doesn't exist. This is why some critics call string theory a "theory of anything."
Cheers,
IT
Power corrupts. PowerPoint corrupts absolutely.
Some say this could even lead to the abandonment of either string theory or inflation
So if the facts don't match the theory, just abandon the facts. Sounds like a neat idea. It should at least make it *much* easier to come up with a "theory of everything".
Opus: the Swiss army knife of audio codec
Because it is ridiculous.
I might as well said it was created by an Invisible Pink Pony that lives on the moon. Then complain no one take me serious.
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If there is indeed a "theory of everything," it may be so far outside the range of our current intellect that the complete development of the theory could take centuries. If we are willing to throw away anything just because it hasn't made a new prediction within 30 years, we might be dooming ourselves to NEVER figure it out.
Exactly.
The main problem many have with the devotion to string theory is that we have a lot of highly-educated thinkers devoted to a theory that may have neither practical applications nor usable physical methods within their own lifetimes.
Perhaps a wiser choice, as a society, would be to limit those studying string theory to a smaller fraction of physicists, while retasking the rest to more rewarding areas of theoretical physics that might have some use to us as a society.
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Some say this could even lead to the abandonment of either string theory or inflation, though no one is ruling out a possible resolution yet.
Actually, I protest. About any decent physics department on earth has more people not working on string theory than people who do. Heck, I even know some universities that don't have string theory group.
Problem is that the other fields are far more difficult to explain and draw little to no attention.
#1) Respect the privacy of others. #2) Think before you type.
String theory is probably the only theory that really supports inflation. If the net energy in the universe is constant, then the net curvature must be constant, therefore it could only appear smaller if curvature were balanced between other dimensions.
We at slashdot are scientists, specialists and kernel hackers. Your FUD will be found out.
If the universe is expanding, what is it expanding into and why isn't that considered part of the universe?
I'm not a string theorist, but I am a cosmologist. Here are some thoughts:
Inflation has not been "confirmed" in away way. It's the best explanation for a very very limited number of datapoints we have on the "early" Universe. Very smart people (e.g., Sean Carroll, now at CalTech) have made convincing cases that inflation is actually incoherent in important ways. I have spent quite a bit of time trying to come up with alternatives to inflation, and it's damn hard -- it "works" very well, in the sense that it solves a bunch of problems all at once that are hard to solve individually. But it does invoke plenty of nonstandard physics we've never seen in the Universe, let alone the lab.
Inflation and dark energy are deeply connected. They both require something called "negative pressure". Negative pressure is bizarre, and actually is from a Newtonian perspective a violation of the conservation of energy (in General Relativity, energy is not conserved -- rather a complicated combination of numbers some of which refer to what we'd measure as energy is conserved.) Negative pressure means that if you take a box of the stuff, and let it expand, at the end of the day there's actually more stuff in there than you started with.
String theory should better be known as "a collection of approaches." It does not have the coherence of, say General Relativity, which is a mathematically closed system. Talking about "giving up string theory" is kind of dumb -- essentially what you are saying is "do not try to do the following large class of calculation." There are definitely competitors to string theory, but none have captured the attention of a highly fractious community the way string theory has.
Not sure if anyone's still reading this thread, but I'm happy to talk more about it. Reply with questions if you like!
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Smolin, Wolfram and others consider evolving graph-theoretic networks as a more likely base model for a theory of everything.
... an interesting experience which helped inspire my OSDC 2004 'Design on the Fly' paper (PDF) and slides (S^5 HTML).)
My first, and to-date only, experiment with a simplest-of-class evolving graph very soon produced a good analogy of inflation.
(Before I figured out what was going on, this 'inflation' had the side effect of making my puter seem to 'go away' even when I capped the clock at ten ticks
-- Our systemic servants do not good masters make.
I don't supposed that inflation is just the perceived rate of expansion, looking faster in hindsight because it was occurring within a very tiny pocket of terrifically distended spacetime. Then again, IANANuclearPhysicist. :)
I remember some Australian dude finding some discrepancies in light observed from far far way galaxies. and his conclusion was that either the electron-proton mass ratio or the speed of light has changed over the course of time. if c has changed (slowed?) over the life of universe then faster-than-current-c travel does not seem mysterious at all.
The article seems to be sorely lacking in details, and when it finally does mention the specific models, it seems that they only actually tried to get inflation out of toroidally compactified Type IIa String Theory, claiming that this was generic. If anything, this is the opposite of a generic situation. Toroidal compactifications preserve far too much supersymmetry to be generic, and as the article mentions, there are other reasons to expect that inflation won't be visible in the IIa theory. Additionally, the article fails to mention that there are a number of inflationary mechanisms in string theory that seem to be quite generic. Included in these are KKLT, KKLMMT, Brane Inflation, DBI Inflation, and many more stringy inflation models which I haven't mentioned. In fact, if anything, the problem currently seems to be that there are too many viable inflationary models in string theory.
There's no sig like SIGSEG
inflation is a feature of the big bang theory to explain observed phenomena. It is not an observed phenomena itself and need not be explained. String theory doesn't need to have the same features as big bang - it just needs to explain the same observed phenomena.
It seems science really *is* dead after all.
Cosmologists are finding that it is impossible to square string theory with Einstein's theory of General Relativity after all. Some say this could even lead to the abandonment General Relativity...
... if only to ensure that string theorists
around the world do not lose their jobs.
For example there has been ongoing debate for many years now between people who are searching for dark matter and proponents of MOND.
Just some questions about the above:
a) If MOND is about an extremely small acceleration in F=MA, couldn't that be experimentally verified rather quickly by putting a paperclip a certain distance from the moon or the earth? Or something like that. MOND is something like I would have hacked in CMP252 and seems like it can't possibly be right.
b) I'm assuming that they measure the rotation of a galaxy by looking at its stars red shift? But, what if, for whatever reason, stars farther out from the center of the galaxy just happened to be older / younger, so that, they would have a different color of light but not necessarily be doppler shifted? Or is my understanding of red shift completely wrong - like you know that there ought to be a hydrogen line at a certain spot, but if its moved over, you know what the shift is? Is star light that precisely measured from millions of light years away?
This is my sig.
I mean, it has already been determined that 42 is the Ultimate Answer to the Ultimate Question of Life, The Universe, and Everything, right? The real question of inflation should be "Can the Ultimate Answer to the Ultimate Question of Life, The Universe, and Everything be expanded into the Ultimate Answer to the Ultimate Question of Life, The Multiverse, and Everything?"
Anybody want my mod points?
flying apart but they're all knotted again and that's the part the string theorists don't like; being in a strange, topless/bottomless joint without any charm at all.
MSBPodcast.com The opinions expressed here are my own. If you don't like 'em... Think up your own stuff.
And just get rid of both string theory AND inflation.
I scream. You scream. I assume that means we're both acquainted with the problem. We proceed.
Inflation is only a tentative theory, that has no evidence in favour of it. People only believe it because it is supposedly a 'simple' explanation of some things that we can observe today (e.g. uniformity of the microwave background). However it is not so simple; e.g. there is no firm theory of what caused inflation to start in the first place.
It gets talked up a lot more than it is actually worth.
>> Noodles are weak, wimpy string posers unable to carry...
It's "poseurs", you big brutish freedom-fry eating macho pirate!
And while we're at it, I always preferred the term "Flying Pasta Monster" - so much more an elegant
label for an elegant theory.
.
- aqk
F U
Yeah, I bet "string theory" can accomodate not only inflating universe, but stable universe, contracting universe, break-dancing universe, drunken-style kung-fu universe, you name it.
/. crowds).
Perhaps it's time to switch the terminology - stop using the umbrella term "string theory" and the theoreticians won't be so ridiculed by lay public (e.g.,
String theory can accomodate any observation, because it's a Chimera: Just dicker with the dimensions and any empirical inconsistencies evaporate like a fart in the wind. Add or subtract a dimension, change the way the "strings" curl around all the phantom dimensions, and nearly any conclusion is possible. That's why string theory is unable to make a single falsifiable prediction: It makes lots of them, and then when they turn out to be false, the theorists just twist the strings in a different direction.
Mmmm the comment above reminds me of a discussion with a colleage that had a major in physics.
He just finished a book about string theory that indeed supported this point of view:
The author (don't ask me the name, I am unable to remember) worked on early string theory himself. However, he later doubted his very work as no experimental proof could sustain it. He also mentioned the mathematical beauty of string theory and the fact that people became enamoured with it rather than looking for experimental proofs. This hypnotism lead a number of proeminent physiscist to accept this as the Truth and the author says that it is now very difficult not to "believe" in string theory in labs as you would be catalogued as outsider and therefor have more touble to get researtch funding.
Not beeing in the field, I would not be competent to judge this. However, fundamental physiscs is pretty intersting as an amateur.
One of this out of the boxes ideas was that he would introduce another limitation beside the c speed limit and the quantic physics uncertainties ( speed / position) : he states that space itself is not a continum but dimentions cannot be lower than the planck constant and that any system that is smaller to this dimensions is outside physics laws and cannot be understood because such a system would be below an event horison that would bar every attempts for any measurement.
Doing that he make the supposition that black may be systems where matters collapses below this limit and then could be the singularity that COULD trigger another big bang in another dimension.
Seems to be very wild to me but the ideas are fascinating.
...maybe AnsiString will accomodate inflation!
The book sounds like Lee Smolin's The Trouble With Physics which I read a couple of months ago.
Then again, it also sounds like Peter Woit's Not Even Wrong which I've not read.
There is a growing trend of slagging off string theory and string theorists :)
I say we take-off and slashdot the site from orbit... it's the only way to be sure
30 years is not a long time. Be patient little rabbit.
Although this story begins with the proposition that string theory isn't adding-up, inflation itself is susceptible to some probing criticism. For example, neither the relative uniformity of the present universe nor its "lumpiness" (required for matter to form galaxies) are in any way required results of inflation; even the slightest variation in the initial quantum fluctuations thought to be responsible for the non-uniformity produce wildly different outcomes. That our universe came out the way it did, with physical laws and characteristics necessary for galaxy formation (and hence life), is statistically highly improbable. In fact, some inflationists have posited that there is a perhaps an unlimited number of expanding regions of space where these characteristics have not obtained, regions that will never intersect because space itself expands faster then the edges of these individual pockets. Further, inflation doesn't say much about the enormous amount of energy that is required to drive inflation; how does a force that acts so powerfully suddenly disappear and give way to the cause of today's much slower expansion?
An alternative to inflation that preserves much of string theory (at least M theory) is put forth in a book by Paul Steinhardt and Neil Turok called "Endless Universe." http://www.amazon.com/Endless-Universe-Beyond-Big-Bang/dp/0385509642/ref=pd_bbs_sr_1/102-2736756-6626517?ie=UTF8&s=books&qid=1189688680&sr=8-1 The book details some of the intellectual and experimental hurdles in the development of inflation and advocates a cyclic universe with periodic collisions between closely-spaced dimensions. Although the book is non-technical (and I surely would not understand the math if it were included) the authors claim that every prediction inflation makes is equally well predicted by their theory. Additionally, some of inflation's more problematic results are avoided. According to the authors, the WMAP team has predicted that future experiments will be sufficiently sensitive to make measurements of phenomena that have different predictions under inflation and the cyclic model.
In any event, the book is a stimulating read.
Well I know inflation is at least partly to blame for my shoe-string budget...
Where is Gary Larson when you need him?
I wonder if string theory can explain why people feel the need to share any interesting or debatable fact they come across with slashdot, even if the information is multiple years old...
One of the sharpest critiques of string theory is that it isn't really one theory -- it's many, many theories (something like 10^500), depending on how the hidden dimensions are wrapped up.
That's not a critique of string theory, and it's not true either.
String theory is one theory, but with many, many ground states.
This doesn't make it any worse than existing physics such as the Standard Model, which really is one theory out of the infinitely many possible quantum field theories you can write down.
But therein lies the problem: no matter how an experiment turns out, one can cook up a version of string theory that agrees with it!
That's not true. In fact, it's harder to cook up a string theory to explain an experiment than it is to cook up a quantum field theory: there are low energy effective field theories you can write down that can't be obtained from any string theory.
What we really need is a meta-theory (M-theory?) that tells us *which* string theory to use, but so far it doesn't exist.
It would be nice, but we don't really "need" it. There is no such meta-theory which tells us that the Standard Model is the "right" quantum field theory, but that doesn't make the Standard Model or QFT useless. It just means that you have to do experiments to determine which one is right (or rather, which ones are not wrong). Welcome to science.
There once was a race, who, despite the laws of the universe,
tried to compute chaos, putting it into mathematical systems.
They are now known as "The race that used too many resources on too little,
and hence became extinct".
I think it is commendable to try and figure out that which can't be figured out,
but in the end, "the abyss also gazes into you".
You live and you learn; some just choose not to...
Read all about it on Bad Astronomy, http://www.bautforum.com/against-mainstream/61876-gem-rank-1-unified-field-proposal.html. I know I should put it up on the physics archive, but they don't let fringe folks toss pdf's up there about a rank 1 field theory for gravity and light (yes, I figured out how the spin 2 graviton lives in the charge coupling term, if anyone here groks that issue). The test is to measure bending of light around the Sun, but six orders of magnitude better than needed to show Einstein was right, Newton was wrong. The GEM theory predicts 12% more bending, 0.8 microarcseconds, than the Schwarzschild metric. If we detect gravity waves, and measure them along 6 different axes, GR predicts the waves are transverse, and GEM predicts they would be longitudinal or scalar waves. Let the measurements decide!
doug
quaternions.com
Working on new views of old physics at http://VisualPhysics.org
Sound like you are trying to have it both ways. Inflation theory was developed to account for observations about the universe. So if string theory cannot support inflation, then it is not going to be consistent with those observations. Which indicates that observations of the universe can be used to test string theory.
There is such a meta-theory, and it's called experimental science. Since IIa is inconsistent with both dark matter and inflation, progress is best served by allocating investigative resources to other theories. Thus, this is a practically useful result. Moreover, it may form the template from which other results, which eliminate larger classes of string theories, can be derived by abstraction, generalization, or clever virtuoso tricks. Ultimately, some number of string theories will remain without a sufficient refutation to discount their investigation. The number may be large, small, one or zero. If the number is over-unity, they may admit abstraction, such that a single formalism can be used to make all measurable predictions of any/all theories. This is sheer speculation, but it is consistent with the history of the theory. But even if such an abstraction never emerged, and we were stuck with multiple multually inconsistent theories, each consistent with all practicable observations, this would not be a terrible thing. There's no reason to think that science can determine all physical truths unambiguously -- quite the contrary.
-I like my women like I like my tea: green-
for expansion, strings are fine. For inflation (rapid expansion), a stringbuilder would be better.
Could someone explain to me what the justification behind unifying all of the fundamental forces is? I'm sure that it would be nice from a physical standpoint to have all of the forces be different facets of one fundamental force, but what if they aren't? Is there any groundbreaking research going on that assumes differently?