On PBS tonight- The Elegant Universe-A theory of everything.

[Brimstone]

Airing tonight on your local PBS channel for people living in America, NOVA will have the first part tonight. It's all about string theory.

Here is the PBS homepage

http://www.pbs.org/wgbh/nova/elegant/

 

[CosmoKramer]

Until someone can explain what the dark matter/energy is all these TOEs are just bullshit. Qualified bullshit but bullshit none the less.

 

[Natoma]

I want my warp drive.

Seriously though, I've been looking forward to this special for a while now. String theory is definitely just a tad above my head when it comes to the details, but from what I understand of it, it makes a lot of sense and could end up being the unifier for Quantum Physics and General Relativity.

If someone can prove it's true, it'd be up there with the greatest scientific findings of the past few millenia.

 

[Brimstone]

I want my warp drive.

Seriously though, I've been looking forward to this special for a while now. String theory is definitely just a tad above my head when it comes to the details, but from what I understand of it, it makes a lot of sense and could end up being the unifier for Quantum Physics and General Relativity.

If someone can prove it's true, it'd be up there with the greatest scientific findings of the past few millenia.

Like Cold Fusion.

 

[Ilfirin]

Like Cold Fusion.

 

[pax]

Cool shows... does a pretty good job of bringing us up to date on the state of the art of physics. Ill be following this series ....

 

[bloodbob]

I want my warp drive.

Seriously though, I've been looking forward to this special for a while now. String theory is definitely just a tad above my head when it comes to the details, but from what I understand of it, it makes a lot of sense and could end up being the unifier for Quantum Physics and General Relativity.

If someone can prove it's true, it'd be up there with the greatest scientific findings of the past few millenia.

Like Cold Fusion.

Cold fusion is compeletly valid just u need some pretty high pressures just keep pressurising and removing heat ( so u don't have hot fusion ). U'll either end up fusion or a really wierd quatum state.

 

[Bouncing Zabaglione Bros.]

Re: On PBS tonight- The Elegant Universe-A theory of everyth

Airing tonight on your local PBS channel for people living in America, NOVA will have the first part tonight. It's all about string theory.

Here is the PBS homepage

http://www.pbs.org/wgbh/nova/elegant/

I thought string theory had been superceded by membrane theory a couple of years ago? http://www.bbc.co.uk/science/horizon/2001/paralleluni.shtml

Edit: Added reference URL to BBC Horizon documentary and transcript.

 

[Deepak]

This universe is so complicated.....there are too many questions to be answered...damn

 

[Ilfirin]

Like Cold Fusion.

Just to clarify..

Atoms coming together and fusing at temperatures far less than that of the sun (aka Cold Fusion) is an undeniable fact of experimentation (experimentation that is now approaching 80% in reproducibility), despite whatever the media or a good majority of scientists might tell you. The question is whether or not you get any extra energy at all. It might not be Cold Fusion by the sci-fi standards, or what we've all come to identify with it, but it fits the strict definition of the words (Fusion at relatively 'cold' temperatures).

Also contrary to popular belief, these are NOT "some nuts" on LSD working out of their basement. They're nobel laureates, MIT professors, and some of the best physicists in the world that have come to the conclusion that something is definitely happening with cold fusion, and it's not just experimental error.

But anyway, there was a pretty interesting news story a few months ago on this.

 

[nutball]

Until someone can explain what the dark matter/energy is all these TOEs are just bullshit. Qualified bullshit but bullshit none the less.

Errrr.... huh? :?

You do realise it's quite possible that dark energy is bullshit? Dark energy is a mathematical construct required to reconcile current models of the Universe with current observations. This tells you one of two things: (a) dark energy exists, or (b) the models are wrong.

I'm a betting man, and I have a little inside knowledge on how the scientific process works (specifically the fields of astronomy and cosmology) and my money is firmly on (b).

Look at is this way: the current favourite model superceded the previous favourite model (because the previous one was flawed, ie. "wrong"). The previous model superceded the model before that for the same reason. And so on. It doesn't take a genius to work out where we're going to be in a few years, decades, etc. : with a different model, maybe one which doesn't require novel fabrications such as dark energy.

 

[CosmoKramer]

You do realise it's quite possible that dark energy is bullshit?

Anything is possible but the evidence is certainly not getting weaker...
http://www.newscientist.com/news/news.jsp?id=ns99994314

Note that the above is empirical evidence. Unlike any string theory.

Dark energy is a mathematical construct required to reconcile current models of the Universe with current observations. This tells you one of two things: (a) dark energy exists, or (b) the models are wrong.

Exactly. (waiting for the penny to fall down)

You don't think it's a wee bit premature/moronic to declare a Theory of Everything when important observational phenomena have no explanation?

I'm a betting man, and I have a little inside knowledge on how the scientific process works (specifically the fields of astronomy and cosmology) and my money is firmly on (b).

That's very interesting and I hope you're right. Do I need to repeat myself about the stupidity of naming a theory the TOE again...

Look at is this way: the current favourite model superceded the previous favourite model (because the previous one was flawed, ie. "wrong"). The previous model superceded the model before that for the same reason. And so on.

I don't share your "linear" view of science - I suggest you read Karl Popper. Everything seems to be shaping up for a major paradigm shift in physics.

It doesn't take a genius to work out where we're going to be in a few years, decades, etc. : with a different model, maybe one which doesn't require novel fabrications such as dark energy.

If there is a paradigm shift in physics in the coming years I think you'll be surprised...

 

[nutball]

Look at is this way: the current favourite model superceded the previous favourite model (because the previous one was flawed, ie. "wrong"). The previous model superceded the model before that for the same reason. And so on.

I don't share your "linear" view of science - I suggest you read Karl Popper. Everything seems to be shaping up for a major paradigm shift in physics.

It doesn't take a genius to work out where we're going to be in a few years, decades, etc. : with a different model, maybe one which doesn't require novel fabrications such as dark energy.

If there is a paradigm shift in physics in the coming years I think you'll be surprised...

Well, firstly I hate the phrase "paradigm shift", it sounds like the title to a crappy sci-fi movie.

But anyway, it won't surprise me at all, and indeed I am expecting it. That was what I was saying (perhaps an obscure way). The current model is wrong (almost by definition), and will change. A totally new model will come along. In between are the paradigm shifts you're after. Well, what I mean by paradigm shift, anyway. It's quite possible that something will come totally out of left-field, and have the same impact on current physics that Relativity and Quantum Theory did at the turn of the 20th century.

If by "paradigm shift" you mean that physicists are going to change the way they work and somehow, magically, start coming up with models which "right", rather than some horrible abstraction of reality, then I just don't agree.

From a philosophical stand-point I just don't think a model can ever be more than just a model. I guess what I'm getting at is that philosophically I draw a distinction between a model that happens to correctly predicy any observable, and The Truth(TM). They aren't the same thing IMO.

 

[Fred]

Right.. First off Brian Greene is one of my proffessors, and a very smart man. Unfortunately, dark energy and dark matter are FACTS, that won't change now, in our lifetime or ever. The probability that our experiments were wrong is something like 1 in 1000 at this stage. Whether or not our models are wrong, is irrelevant. Any new model of General relativity or whatever, will have to accomodate the data.

Two, Dark matter is not a problem for String theory, or any other current quantum gravity theory. Its more a problem for astronomers, and regular particle physicists. The current majority feel its the lightest supersymetric superpartner, which will be observed in about 4 years at CERN. If its not observed and/or doesnt exist, its not a big deal for quantum gravity theories, it just means whatever is causing the anomolous gravity is something else (there are many candidates).

Dark energy otoh, is a serious problem for our current understanding of physics and quantum gravity. Its really a big problem, for it is the state of absolute nothing that we don't understand. Current vacuum state calculations from quantum field theory gives an estimate that is either infinity, or with an additional likely assumption about 120 orders of magnitude off. I challenge anyone here to make a theory that gives a worse prediction.

Nearly everyone believes its the quantum gravity sector that is throwing things off.

String theory in its current form seems to give values for the cosmological constant (the simplest model for dark energy) that are negative, not positive. Everyone knows these are just toy models, and not realistic, however the general trend seems to indicate that things get 'negative' far easier than they get positive.

Since String theory is not really a 'theory' yet, but rather an ongoing program that studies quantum gravity, its unfair to dismiss it on this point.
When they get things ironed out mathematically, and parts start to get constrained and it still produces a bad prediction, then yes, its falsified.

You have to understand, in many ways, if you follow the logic of quantum field theory (the most successful theory of all times) according to String theorists, there is absolutely no alternative. All roads lead to string theory, is the popular saying. Its not exactly rigorous, but you can for instance change a whole slew of assumptions, and think your changing much of the dynamics of your theory. Yet in the end, almost miraculously, you end right back with String theory in disguise.

Thats why its been worked on by the smartest people on the planet for twenty years, despite formidable mathematical and conceptual barriers. Lines of problem solving that ask questions like 'well what else could it be?' all point strongly in favor of it.

 

[Saem]

I thought the show was too watered down and they tried to make it too hip and cool in some lame attempt to appeal to kids.

I was rolling my eyes through a lot of it, since they would state many things but rarely go futher than saying, "THIS IS THE WAY IT IS." I was hoping for more of. "This is how it works."

BTW, the host came across as being very intelligent; however, he was a poor host and every now and then I had the urge to hit mute because his voice bothered me.

 

[DemoCoder]

Fred, don't you see the apparent circular reasoning going on here?

1) you observe universe
2) GR doesn't fit the observations, instead of assuming GR is wrong, you instead assume GR is correct, and that your observations are wrong: that is, there is matter you can't see, dark matter.

Yes, GR is a successful theory, and most observations have matched it's predictions very well , but perhaps the assumption that it can be universally applied is incorrect. Perhaps on even larger scales of mass and distance there is another force at work.

Cosmology seems to be a series of hacks that theorists keep inserting into GR to make the data match up with the theory: Inflation, WIMPs, MACHOs, etc. You think WIMPs are an elegant theory? Sure, let's postulate that 90% of the universe is made up of a very small, but super massive particle that hardly ever interacts with anything and for all intents and purposes, is undetectable. That's a fudge factor if I ever saw one.

 

[Natoma]

Indeed. As we found out with newtonian physics.

 

[Vince]

MOND?

 

[Fred]

All science reasoning is circular.. And thats fine, so long as it matches experiment (which GR does).

Not to get into too much nitty gritty detail, but the Einstein-Hilbert action in General relativity is mathematically the simplest form that you can write down.

You can replace it of course, as you choose, and it has been done many times. In fact, there are GR modifications that fit the data. But the underlying framework is pretty much accepted, it really is nothing more than a system by which you describe a topology in a diffeomorphic way, and one that looks locally flat. The field equations will change, but the language will stay the same.

Likewise, you can write down different spacetime metrics for cosmology (replacing FRW), but again, it is the simplest thing you can write down.. And more importantly, you can treat it as a first order approximation in a perturbation series to most sensible alternatives. And thats the key, b/c no matter what, the cosmological constant 'concept' stays there to first approximation.

The global symmetry group that characterizes our universe is Desitter, not the Poincare group, any new theory will have to at least contain it as a subgroup.. Thats what these experiments tell us!

 

[DemoCoder]

Problem is, you are taking the success at GR "curve fitting" some experiments successfully, and extrapolating that as if it must describe the topology of the entire universe.

Right now, we have a disconnect if you try to use GR at quantum scales. That's what this whole TOE discussion is about.

Could there not be a similar disconnect when you try to take GR beyond just looking at solar systems, stars, and galaxies, and to the level of clusters, superclusters, and the universe at large? What if there is a another effect that acts over tremendously huge distances and time scales that is completely separate from GR, an effect that won't manifest itself at smaller scales of time, space, and mass? Perhaps universe scale topology works differently.


To me, all these theories are WIMPS, MACHOS, and other exotic forms of unobtanium invisibilum that are needed to explain why GR's predictions don' fit observations are a violation of Occam's Razor.

These undetectable particles don't seem to offer any new testable predictions nor any new explantory power.

I'm not an expert on GR, but it seems to me, if observations don't fit the theory, then something is wrong with the theory. This is the opposite situation from QM, where we don't have observations that violate the theory, instead, we have nearly unobservable in principle speculative entities (strings) that don't explain any observations we can make in a laboratory.

Seems to me, we need a new theory when observations don't fit it. Perhaps instead of looking at particle physicists for some wonder particle that will fill the holes in their theory, cosmologists should look at their own models and assumptions.

Perhaps GR is just the 20th century's own version of Ptolemy's Epicycles.

BTW, empircal science isn't circular. Deduction is, Induction isn't. Physical science is based on induction.