A long time ago, in a galaxy far, far away ...
Here it comes the new film of the saga Star Wars, The Force Awakens. Ready to make us enjoy and dream. Full of technology, adventures, and ready to show us the Galaxy. All united with the force.
The force, ... Where is the force in Nature?
Can the Jedi can fell the force, if they can use it, our devices should be able to detect them. Shouldn't they? In order to try to understand what should be the force in the landscape of Science I will remind the definition Master Obi Wan gave to Luke in the first movie.
"The force is what gives the Jedi its power. It's an energy field created by all living things. It surrounds us, it penetrates us. It binds the galaxy together."
He is talking about an energy field that surrounds us, penetrates us and binds the galaxy together. There are two things in the Universe that could respond to that description, and both come from the dark side: dark energy and dark matter.
These two dark concepts are not really well known nowadays. But we do know that they constitute 69% and 27%, respectively, of the content of the Universe. The dark side rules the Galaxy They both are distributed all through the Universe, although dark matter is attractive gravitationally, therefore forming lumps, while dark energy is uniformly distributed and repulsive.
In any case, neither of them has been directly detected yet. Dark energy was postulated in the late XX century in order to explain the accelerated expansion of the universe, observed in 1998. It should be some sort of repulsive pressure that pulls the Universe apart, making it grow faster and faster. But dark energy does not bind the galaxy together. If it continues as it is doing now, dark energy will pull the universe so intensely that it will break it apart, tearing galaxies apart. Dark energy can not explain the force.
In the case of dark matter, the most likely candidate are the so-called Weakly Interactive Massive Particles (WIMPs). These are described as very heavy particles that don't interact through the electromagnetic force. This lack of interaction makes dark matter be almost undetectable (it has not been up to date, although there are efforts in this direction). Neutrinos were candidates for dark matter at some point, but they can only account for 1% of the content of the Universe. Just as neutrinos are doing right now, dark matter should be penetrating us without us noticing it. Dark matter is attractive gravitationally, unlike dark energy. Indeed, this was the first clue to identify its existence in the 1930s. The movement of galaxies, for example, can't be explained with the amount of matter we observe from stars, and it is needed the existence of extra matter to explain it satisfactorily. Also, dark matter is necessary to explain galaxy formation. Without it , probably galaxies wouldn't have formed the way they did.
So, yes, dark matter surrounds us, penetrates us, and binds the galaxy together.
Is dark matter the Jedi force?
Well, if dark matter exists, which a few astronomers do not agree, it should penetrate the ordinary matter that we all are made of: atoms. But it should penetrate living creatures as well as water, rocks, or even stars. Or, ... Obi Wan could be referring to baryonic matter (made out of atoms) when he said living. In a poetic form he could be talking about the matter that we can see, the matter that can create living things (4.9% of the content of the Universe) as living things.
May a Jedi use the force?
The way we interact with things is through the forces, that is right. But these forces are the electromagnetic force, the gravitational force, the weak nuclear force and the strong nuclear force. The two first are long range interactions while the two nuclear forces are very short range, just the size of atoms. But we are all made out of atoms, so whatever sensor the Jedi has to detect the force (if it is dark matter or not) we should be able to build detectors made out of atoms to detect it too. And we can't detect dark matter (if this is the force), yet.
In the Fantom menace, Qui-Gon Jinn talks about midiclorians, some microscopic creatures that live inside us and are the link between the Jedi and the force.
It doesn't matter how long ago and how far the galaxy is, the laws of Nature work here and there, now and then. We should be able to detect it here, in our laboratories. If you want to imagine that dark matter was detectable millions of years ago, and it then decoupled from electromagnetism, we should have already seen it in our laboratories, and there should be signatures of that in the observable Universe, which is not the case. The Universe needs about 7 million years to create life as we know it (or as the one that appears in Star Wars). When the Universe was that age, the temperature of the Universe was very similar to the one we have now. Nature was following the same rules it follows now, and the conditions were the same we find now. The more exotic situation of the first minutes of the Universe had passed long before.
Lots of efforts are focussed nowadays to detect dark matter, and most groups think they will detect it in the next decade or so. Maybe they should include biologists in their ranks to find it earlier.
In any case, may the Science be with you.
Physicist, working in quantum optics and nonlinear dynamics in optical systems. Loves to communicate science.