6 ms·
Scale-invariant instantons and the complete lifetime of the standard model
- IIAOPSW 9y agoIf their wrong no one can call them out on it.
- bryanrasmussen 9y agowell if it ends tomorrow with half an hour warning I am definitely going to let them have a piece of my mind!
- jkingsbery 9y agoI bet you $50 that it won't end tomorrow.
- empath75 9y agoWell, since it’s the result of a long chain of logic based on the standard model and measurement of various constants, they could be proven wrong in a variety of ways—their logic could be faulty, their calculations incorrect, or the standard model itself could be flawed.
- empath75 9y ago> Furthermore, since the lifetime is finite and the Universe infinite, there is likely a bubble of true vacuum already out there, far away. It is sobering to envision this bubble, with its wall of negative energy, barreling towards us at the speed of light. It seems the long-term future of our Universe is not going to be slow freezing due to cosmic acceleration but an abrupt collision with one of these bubble walls. It seems like the more interesting calculation is how far away one of these bubbles is likely to be.
- fooker 9y ago'infinity' is more of a logical construction than a physical one.
- smoyer 9y agoI think your question actually raises a key point ... "one of these bubbles". How accurate is their prediction that these bubbles aren't common? And is there somewhere nearby that might be hiding one? On their time-scale, Musk's goal of becoming an interplanetary species seems like a good near-term hedge. Being able to traverse our own galaxy would be a good second step but exponentially harder. People have discussed the almost impossible task of moving between galaxies (without something like a worm-hole). So, assuming the multi-verse theory is correct, I guess we humans need to look into how to get to another universe before this big cataclysm. (It seems pretty easy on "Stranger Things")
- T-A 9y agoGoing with the paper's result: with 95% confidence, more than 10^58 light years. :)
- amelius 9y agoI think that was about the entire Universe, not our local part of it.
- T-A 9y agoThe result reported by this paper is decay rate per unit volume (see Eq. 6.26). That tells you how long it takes for a bubble to nucleate. After that, it expands at the speed of light. How long does it take for a bubble expanding at the speed of light to destroy an infinite universe?
- morelandjs 9y ago...subject to our assumed framework and chosen prior. People always forget that Bayes theorem only marginalizes over the unknown parameters. It assumes the model is otherwise given (true). You can only marginalize over the known-unknowns, not the unknown-unknowns. People like to slip assumptions into their models where the uncertainties are not accounted for. The reason why everyone trusts the LIGO result is that we have an extremely high degree of confidence in general relativity. More generally, what's even the point of placing a confidence level on a non-falsifiable claim? What utility does it serve?
- aalleavitch 9y agoWe might be able to generate hypotheses using it as a premise?
- quietbritishjim 9y agoFor context: This reply was written when the title on here was "With 95% confidence, we expect our Universe to last more than 10^58 years"
- phkahler 9y ago>> More generally, what's even the point of placing a confidence level on a non-falsifiable claim? One can answer questions like: Is it worthwhile for people to attempt to colonize the galaxy? When things like getting to other stars will take lifetimes, and getting across a galaxy 100M light-years across may take more time than has already passed, one needs to have some idea if there is even enough time left for such undertakings. Of course the lifetime of the galaxy will probably be less than 10^50 years, at least it puts the universe as a whole into better context. And really, in spite of any crazy ideas just putting ourselves into context seems to be important to a lot of people.
- deleted 9y ago[deleted]
- lisper 9y ago> The reason why everyone trusts the LIGO result is that we have an extremely high degree of confidence in general relativity. No, that's not true. The reason everyone "trusts" the LIGO results is because we believe the people running the experiment are trustworthy. The results have nothing to do with GR except insofar as they were designed to test a heretofore untested prediction of GR (which prediction they have confirmed). And the reason we want to test a prediction of GR is that we want to try to falsify it, because that is the way progress is made in science. I think you may have meant to say something about how we cannot know for certain that GR is true, that that's right, we can't. But it's not like Einstein just pulled GR out of a hat. It's the only known solution to the problem that fits all of the known data. That doesn't prove it's true, but it is the best explanation we have so we might as well carry on as if it's true until someone proves otherwise or comes up with a better idea.
- xchip 9y agoPhysicist here: I hardly understand this paper so don't worry if neither do you.
- pw6hv 9y agoI don't understand what is the point of your comment, I am a physicist and I understand this paper but this does not mean that others should worry if they don't.
- andrewmcwatters 9y agoI think it's public commentary on the ease of consumption of these papers on HN on a wider scale than just physicists.
- fwdpropaganda 9y agoIn your opinion, what does it say about HN that people have the need to say "this is very complicated, don't worry if you don't get it"?
- AnimalMuppet 9y agoIt says that people here expect to be able to understand things. "I'm not smart enough to understand physics" is not a normal self-image on HN.
- fwdpropaganda 9y agoBingo.
- gus_massa 9y agoNice. Can you ELI25 it? I only skimmed it. I don't understand it now, but I guess that in a week I could get a good enough understanding if I skip the most difficult parts. So my possible wrong ELI25: The vacuum can transform spontaneously in another type of vacuum (like liquid water transform into ice at low temperature). Lucky this is very improbable because otherwise we would be all dead, and the transition is due to quantum tunneling. To estimate the probability of the transition it is necessary to calculate the contribution of the virtual particles in the loops in the Feynman diagrams. A naïve calculation has too many infinite values to be useful. In this article they calculate the contribution of multiple virtual particles, in particular when the Feynman diagrams has many loops. They have a nice pattern and somehow they cancel (most?) of the infinite values. With this new calculation they can estimate how long we should wait until this tunneling effect between the two vacuum destroy the universe and luckily it's a long time. (Perhaps other thing can kill all of us before :).) For this calculation it is particular important the mass of the heavy particles. (Linkbait title: "Scientists say that God's particle may open portal to universe doom at any moment". Sorry. I couldn't resist.) As I said earlier, this short version may be wrong. Any corrections or missing important points are welcome.
- PaulHoule 9y agoTalk about fine-tuning! How is it we are in the metastable area?
- Coding_Cat 9y agoThe anthropic principle, had we been in an unstable region, we wouldn't be able to talk about it now. A completely stable universe might also have some issues that are not immediately clear.
- pw6hv 9y agoThat's actually a very good question. Moreover, if inflation really happened in the early universe, its almost impossible that the Higgs would have remained in the metastable vacuum during that period. Thus only fine-tuning wouldn't be enough to explain our existence. More on this: https://arxiv.org/abs/1505.04825 https://arxiv.org/abs/1505.04825
- Maybestring 9y agoSome systems are self-tuning, perhaps that's what's happening. https://en.m.wikipedia.org/wiki/Self-organized_criticality https://en.m.wikipedia.org/wiki/Self-organized_criticality