New Idea Solves Three Physics Mysteries at Once: Post Quantum Gravity

for the first time in four decades physicists have found a new approach to solving a problem which is almost a century old how to combine quantum physics with gravity I told you about this new approach called postquantum Gravity from Jonathan oppenheim briefly Before Christmas he and his collaborators are now saying that the idea also explains dark matter and dark energy let's have a look this video comes with a quiz that lets you check how much you remember quantum physics and gravity don't get along with each other very well quantum physics is what we call a non-deterministic theory it has a random element it has buil-in uncertainty and it sets limits to what you can know and do we often say that Quantum particles can be in two places at once but really what the math says is that it doesn't make sense to say there in any particular place gravity on the other hand is described by Ang 's theory of general relativity it assigns a time and place to everything it's deterministic the future follows from the past and the only uncertainty it has is that stemming from our own lack of knowledge there have been many attempts to unify the two and create what's known as a theory of quantum gravity the best known approaches give Quantum properties to gravity and include String Theory Loop quantum gravity and ASM totically safe gravity the path less taken is to leave gravity a non-quantum theory or to change something about quantum physics these ideas have not worked out all that well so far oppenheim's new idea post quantum gravity now is to combine gravity and quantum physics by giving a random element to gravity this Randomness doesn't come from anything it's the fundamental ingredient it's the starting point this is just like the randomness of quantum mechanics does not come from anything else it's fundamental a starting point just a property of nature The Innovation that opheim brought in now is that he found a way to combine the mathematics of both types of Randomness into one framework in this postquantum Theory Quantum remains non-quantum and particles remain Quantum however these two sectors communicate with each other because particles have gravity and that gravity in return influences the particles in oppenheim's theory this works without contradictions because these two Randomness fit together in the new paper now opheim and his co-author Russo say that this Randomness changes the law of gravity under certain circumstances and those circumstances are when the acceleration of an object is very small if you followed the debate about Dark Matter then this will immediately ring a bell because because the major competitor of dark matter is a modification of Einstein's gravity known as modified Newtonian Dynamics or mon for short and that becomes noticeable wait for it at small acceleration the reason this modification at small acceleration can appear as if there was dark matter is that the acceleration on average depends on the strength of gravity if you're near a planet or a sun like most of you probably are then you experience a noticeable pull of gravity from those heavy objects if you interpret that as a force then that gives rise to an acceleration the further away you are from heavy objects the smaller the acceleration however the overall gravitational pull coming from the entire galaxy gets smaller the further away you are from the center this is just because most of the mass of the Galaxy sits in the center it now turns out that if you assume that ground gravity gets stronger at small acceleration then that can explain the observations attributed to dark matter in galaxies this is in a nutshell the idea of M opheim now says that when they look at the changes that they get to the law of gravity from this Randomness they see a similar Behavior the smaller the acceleration of an object the more it's affected by the randomness they derive an equation that's similar to Newton's law of gravity for the Newtonian potential and then they have some unusual contributions they show that these extra contributions seem to be similar to those of modified nutonian Dynamics which is dark Matter's competitor and for good measure they also get a term that they say looks like dark energy on Twitter opheim writes folks something seems to be happening we show that our theory of gravity can explain the expansion of the universe and Galactic rotation without dark matter or dark energy okay but you didn't come to hear what the authors say about their own paper at me guess you came to hear what I say all right I actually don't like doing this but here we go I think it won't work the reason is that the equation they have is linear in the Newtonian potential to make modified gravity work you need an equation that's nonlinear in the potential I haven't had time to think about it much but I expect that if you look at the scaling of the asmic Velocity with the mass of the galaxies it won't come out correctly the only differential equations that get this right have a rather peculiar nonlinear form with a 3 over2 exponent so yeah I kind of wish it had work but I don't think it will but you know I'm just an old grumpy woman who thinks she's seen it all before so maybe it turns out that what I just said in front of some 100 thousand people was complete nonsense and if that turns out to be so you don't want to miss my public embarrassment so stay tuned if you'd like to learn more about recent scientific developments I recommend you have a look at Nautilus magazine Nautilus is a Science magazine that keeps you up to dat on the most relevant topics that are being discussed today they frequently have scientists writing for them who will tell you the inside stories I've written a few contributions for them myself most recently about John oppenheim's theory of postquantum gravity Nautilus comes with a digital an a print version and it's just a pleasure to read they really put a lot of effort into writing and the graphic design is top what I particularly like about Nautilus is that they cover all areas of science from astronomy to economics history Neuroscience to philosophy and physics if you use our custom link join nautilus.com Saina you get 15% off your membership subscription so go and check this out thanks for watching see you tomorrow

Channel: Sabine Hossenfelder

Views: 449,721

Keywords: science without the gobbledygoook, hossenfelder, science humor, science news sabine, physics, physics news, postquantum gravity, post quantum theory, post quantum gravity, post quantum classical gravity, dark matter, dark energy, quantum gravity, new physics theory, astrophysics, science news

Id: PBA9ac3vg1w

Length: 6min 59sec (419 seconds)

Published: Tue Mar 12 2024