Are branes valid science or just fancy math?

[physorguser]

I can't get my head around it when theoretical physicists talk about types of branes and how these branes could be described in order to account for a cause of the initial creation event as it is now posited.

It seems to me that because it is obvious that we will never be able to get enough energy in particle accelerators to probe anything near the Planck length as it is, then it seem that a concept of coming up with a cause that could explain the cause of the original postulated Planck length and time creation event seems less than pointless as it is logically impossible to ever being subject to testing of any kind whatsoever.

So it seems that it can only be a mathematical exercise with no basis as all in any empirical reality, however anyone cares to define reality.

Yet in spite of this, theoretical physicists seem to talk about stuff before the initial creation event as if it can be known in the future as a scientific 'fact'.

Is there any point to it other than clever math for maths sake? I mean can anything before the creation event be seriously regarded as science?

 

[bapowell]

Yes, theories of Planck scale physics are beyond the grasp of modern experimental science. As a result, all such theories (like string theory, loop quantum gravity, etc) are really more bodies of conjecture and hypothesis than theories, as they have not been empirically verified. That said, I don't know why you call testing such theories "logically impossible" -- what's logically impossible about it? Practically impossible, yes -- but in principle, testing such theories are not even physically impossible let along logically impossible.

Given that we can't test these theories yet, are you suggesting we just stop developing a physical framework for potentially understanding these theories in the future? Why? The history of science is full of theories that made predictions at the bounds of technological and practical possibility -- think of particle physics in the latter half of the 20th century. Think of the Higgs boson -- it was predicted some 50 years before humans could harness power sufficient to discover it. Should we have waited until the technology became available before science began to develop an understanding of symmetry breaking in the Standard Model and the origin of particle masses in gauge theory?

I agree that proponents of quantum gravity sometimes evangelize a bit too much. And, yes, it can be argued that applying these speculative theories to real-world problems (whether it be through braneworld conjectures or something else) is premature and a little presumptuous. But, that's how science ultimately works: you make a prediction based on conjecture or a hypothesis and then you direct experiments to verify it. The problem today is that these speculative conjectures are way ahead of the experimental enterprise, and so there is a lot of speculation going on that is lacking empirical verification, like water backing up in a clogged drain. I attribute much of that development to the "publish or perish" paradigm of professional academia -- people have to write stuff, even if it's totally tenuous and fantastical, so that they can stay in the field.

 

[physorguser]

Thanks for your reply. You have slightly misunderstood probably due to my clumsy sentence construction. I agree with your last paragraph. I was of the impression that to probe the Planck scale would require a particle accelerator the size of the Galaxy or some such nonsense, but anyway I was not referring to that as 'logically' impossible, I was meaning 'before' that. Which is what it seems to me that all this 'brane' stuff postulates, some sort of 'cause' prior to, (notwithstanding that there is no 'prior to') the moment of the initial creation event.

So yes I fully agree and support and expect that we will be way ahead of how small we can probe, but I'm particularly talking not even of strings which are mathematics to do with events on this side of the big bang at least. It's this brane stuff, you know like two branes colliding and then our universe popping into existence, or millions of universes popping into existence or whatever the speculation it doesn't matter the point being that it's all on the wrong side, as it were, of the big bang. It is that stuff I was referring to as 'logically impossible' to ever test.

My question is, is the fact that it can never be tested even in principle mean that it should be talked about as science rather than just maths? It seems like some sort of Victorian type frivolity like ingesting nitrous oxide. Coming up with plausible math to explain the cause of the creation event, I mean.

You see what I can't wrap my head around is that even though that string theory is as you described it, it can still legitimately be in the realm of science because there remains in principle future tests, events before the BB are not. Are they? There never seems to be a separation. We get smaller and smaller in the scope we speculate about, then we get to this very nebulous area around the Planck length, then it's as if while no one is noticing someone just goes that little bit further and suddenly we are in this impossible 'before the big bang era', that very era that cannot be spoken of if for no other reason the concept of 'before' is supposed to be nonsense.

 

[bapowell]

I see. Thanks for clarifying. I guess the only point I would offer is that in these colliding brane theories and other "pre-big bang" models, the big bang is simply not *the* moment of creation -- it's just the beginning of expansion in our *observable* universe. Since there's nothing special about "t=0", these theories can have physical effects on the CMB, our modern day universe, or whatever. But, certainly -- we need to consider these theories within whatever context they prescribe for the universe, the big bang, pre-big bang, etc. If they describe a cyclic universe that was somehow past eternal, well then there's is nothing at all special about our big bang and there's no problem -- logically or scientifically -- with theorizing about them. If, however, they describe the birth of *the* universe, as in "all there is", and in so doing describe dynamics that are in some sense "outside" physicalism or objective reality as most sane people understand it, then -- yes. Those theories are nonsense of the highest pedigree.

My understanding is that brane theories and most other pre-big bang proposals in physical cosmology are safe, as in they treat our big bang as nothing particularly special -- as just one event in a larger spacetime manifold with an extensible past beyond our "t=0".

 

[Tanelorn]

I just took M-Theory, where all possibilities are contained in 11 dimensions, as one possible solution or idea or description for something greater than the Universe, something which we will probably never be able to know.

M-theory - Wikipedia, the free encyclopedia

For me the biggest reasons for believing in the possibility of something greater, is that the Universe appears to be temporally finite, and quite young, at least compared to something eternal, and so there almost certainly has to have been something which caused the BB to happen. So I look forward to reading of more similar possibilities in the future.

 

[mjacobsca]

You seem to be under the impression that the only way to test these theories is to probe the universe at the Planck Scale. That is one way to go about it, but certainly not the ONLY way.

Theorists are working on ways to explain large scale structures based on these theories, and certainly those large scale structures are visible with current technology. Effects on background cosmic radiation, dark matter formation, and gravity waves are all things that may be testable, should a theory need them.

So yes, if we only stick to smashing things apart, we may never be able to probe anything of value at the Planck Scale. But if we continue to let the field advance, we may yet find things we CAN test. So in my view, string theory and loop gravity and others do have the possibility of becoming more than just fancy math.