Excerpt from huffingtonpost.com
I am a huge science enthusiast and an unabashed science fiction fan. There are tons of really cool stories out there that fire the imagination and even inspire young people to go into science. (I know they did me.) But I also know the difference between fiction and fact and there is a clear distinction between the two. Fudging that boundary cheapens real science.
If you're a science geek and internet denizen like me, you've encountered a lot of stories over the last few days with titles along the lines of "LHC scientists poised to discover parallel universes." And that's just wrong. It completely misrepresents an otherwise reasonable physics article published in the eminently reputable journal Physics Letters B.
"Absence of black holes at LHC due to gravity's rainbow," written by Ahmed Farag Ali, Mir Faizal and Mohammed M. Khalil, describes a speculative idea to explain why black holes haven't been observed at the LHC. But to understand their paper, you first have to understand why black holes at the LHC were a possibility.
One of the biggest mysteries in modern physics is why gravity is so much weaker than the other known fundamental forces (electromagnetism and the strong and weak nuclear forces). While we have no real idea why this is true, one idea was proposed is that there exist more dimensions of space than the familiar three in which we live. If the other three forces are constrained to three dimensions, while gravity can spread into others, then maybe the weakness of gravity is an illusion. Maybe gravity is just as strong as the other forces, but appears to be weak just because it "has more places to go." I made a video that explains this better.
Now we know that this idea has issues, because Newton's Law of Gravity tacitly presupposes three dimensions and we are able successfully launch probes to distant planets. Ordinarily, that would kill this whole idea, but there is a loophole. Suppose that these additional dimensions of space were just very small, say smaller than an atom. Then the astronomy argument wouldn't hold and maybe the extra dimension idea is saved.
So how would you demonstrate these extra dimensions? Well the easiest way would be to study very small things. When you started studying things that were about the size of the extra dimensions, then you'd be entering the realm where gravity is strong. And if gravity is strong and you concentrate enough energy, you will make a microscopic black hole. Thus searching for microscopic black holes is a serious scientific proposition because if we find them, we've also found extra dimensions.
Scientists looked for black holes in the data taken by LHC scientists during the 2010 - 2012 running period and none were found. From that observation, scientists were able to set limits on the maximum size of additional dimensions.
The paper of Ali et al. explores how one can retain "bigger" extra dimensions (where bigger still means subatomic in size), given the non-observation of black holes. What they argued was that an effect was overlooked in which a deformation of space by quantum gravity would change the size at which black holes would form. If their idea is true, it might be that we have to look for objects smaller than the new dimensions to see black holes.
Now this paper might be right or wrong, however the connection with parallel universes is entirely misleading. People think of parallel universes like the Dr. Who episode "Doomsday" in which the Doctor and his companion were marooned in separate, but parallel, universes. (See, I told you I was a science fiction geek.) And that's just not true.
Black holes are the signature of subatomic extra dimensions, not parallel ones. Plus remember that these extra dimensions are ones from which electromagnetism and the strong and weak nuclear forces are excluded. So there is no possibility of making atoms there. Further, since these extra dimensions must be smaller than a proton, that's another strike against the possibility of anything resembling ordinary matter in them.
In short, the title of these articles is entirely misleading. And that's a shame, because the idea of extra dimensions is already incredibly exciting. It would mean that we would have to rewrite our textbooks. But there is no reason to cheapen such a momentous discovery with sensationalist and incorrect science.
These articles will eventually disappear, hopefully into oblivion. In the meantime, don't get caught up in the misleading hype. Instead, keep your eye open for >>real<< scientific measurements from the LHC. They will be exciting enough.