Slashdot Mirror
Why We Think There's a Multiverse, Not Just Our Universe
An anonymous reader writes "It's generally accepted that the Universe's history is best described by the Big Bang model, with General Relativity and Quantum Field Theory as the physical laws governing the underlying framework. It's also accepted that the Universe probably started off with an early period of cosmic inflation prior to that. Well, if you accept those things — as in, the standard picture of the Universe — then a multiverse is an inevitable consequence of the physics of the early Universe, and this article explains why that's the case."
But the turtles appear out of nowhere and are very far apart.
Why do cosmological theories of any merit always sound like they were written by Douglas Adams?
Please do not read this sig. Thank you.
or something less stupid, instead?
It doesn't make any sense to say that it's one big thing, but not one big thing at the same time.
Kind of like saying it's not one big cake sliced into wedges, it's lots of little cakes that have nothing to do with each other.
AND YET THEY OCCUPY THE SAME PLATTER.
I know it's karma suicide to post on something like this saying "I don't get it", but, well, I don't get it.
I've been reading about inflation, multiverses, and whatnot for a very long time at this point, and I like to think that I can give a reasonable explanation comprehensible to nontechnical people. I've come across some articles that were a lot of work to get through, and I've given up on some because I don't have the necessary math.
But this article was terrible. Its grammar is good and not overly complex; it doesn't use a lot of obscure words. It's written like a nice popularization piece, with important parts called out in bold and lots of illustrations. But the illustrations are baffling -- what's that "getting closer to a sphere" four-panel diagram credited to Ned Wright, and where does the text refer to it? What the heck is going on with those diagrams from Narlikar and Padmanabhan? What's with the black space-balls rolling around on the mini-golf course at the end?
I'd wonder if this is a Sokol-type troll, but I don't see anything obviously wrong in it -- there's just a bunch of stuff there that looks like explanations, but apparently isn't. Or maybe I'm just having a bad night.
I think the next greatest feat in physics will not be a new discovery, but just figuring out how to explain the current state of knowledge to a high school student. How can the field progress if only a handful of people actually understand the information we now possess?
I'm not sure I understand what you mean. Are you saying we should only pursue theories and bodies of knowledge if the average idiot can understand them? I'm sure you'll agree that if it makes sense for physics, it makes sense for all areas, including... engineering.
So say goodbye to television, GPS (oops, there's some relativity physics in that too), computers of all sorts, and possibly even non-electronic internal combustion engines.
I'm willing to continue relying on people who deal in knowledge I don't understand, as long as I'm satisfied they're constrained by peers who are incented to find flaws in their arguments to keep them honest.
Hell, most people don't understand what *I* do for a living, and I'm just a senior manager in healthcare information systems.
I disagree that he's only defined causally disconnected regions; this story actually has a definition of multiverse beyond regions outside of our lightcone. Note one of his later images: a single level 1 universe contained multiple regions which are not causally connected yet are part of the same clump that moved from the false vacuum to dumping energy into matter and radiation.
Any grouping like that is fundamentally isolated because the boundary region that remains in the false vacuum continues to exponentially expand, quickly isolating the clump. Even if the clump itself triggers a conversion of the false vacuum around it, it sounds like the isolation proceeds so much faster that it will be forever isolated by expanding false vacuum regions. With time, we could reach places that are not currently causally connected. It doesn't sound like we could overcome this expansion so easily.
There's no mystery about that. The party that's in power always wants more power and the opposition always opposes it. In that the Democrats and Republicans are exactly the same. The teabaggers you're so unfond of are the only ones in the nation who want the government to have less power even when their guys win.
Violence is like duct tape. If it doesn't solve the problem, you didn't use enough.
They won't suck like our current politicians.
They will suck in interesting new ways.
-
- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
Rising health insurance prices were doing that anyway, with or without Obamacare.
Really? How odd that the number of uninsured was at a pretty much constant level. Now with the ACA, you have people who can't get insurance at all, have people who's policies have been fully cancelled and can't get insurance at all, and even more people who's rates have climbed to a point where they could afford insurance, they now no longer can.
I'm sure that you also believe that you can keep your insurance, and your doctor too...well...if you can find a doctor.
Om, nomnomnom...
"Give me a phone book and a week and I'll improve on every nationally elected official just picking names at randomâ¦"
You don't need a whole week.
Sociopaths rise to the top disproportionately (politicians and other power seeking people). Sociopaths make up about 3-5% of the population. Picking 10 names at random (forget even asking them any questions) would statistically get you at the very least a more decent set of human beings.
http://www.rootstrikers.org/
Isn't it hubris to use the word observable? I mean if we've learned one thing by now, it's that just because we haven't observed it, doesn't mean it's not observable. What if one day we figure out how to conduct/observe/measure one of the particles that only shares one dimension with us, and we're able to make circuits/optics using these particles instead of conventional matter to make instruments that can observe a whole different band of matter/energy...such as 'antimatter'. It's quite possible then once we overlay that data the universe won't look so flat or even to be expanding.
Sociopaths rise to the top disproportionately (politicians and other power seeking people)
You're quite correct. It's a phenomenon almost akin to some sort of natural law:
“Society is like a stew. If you don’t keep it stirred up, you get a lot of scum on top.”
Edward Abbey
It seems to me that we have the vote as our only real method of agitation. No surprise then, that our vote matters less and less as society marches on.
..Mullah or Pope, Preacher or Poet, who was it wrote: "Give any one species too much rope and they'll fuck it up"?
Scientists are not so naive as to simply think "it is expanding now, therefore it has always been expanding." The main reasons why we think there was a big bang are (http://en.wikipedia.org/wiki/Big_Bang#Observational_evidence):
1) The universe is not just expanding, it's expanding in such a way that the relationship between distance and speed matches up neatly along smooth curves.
2) We can see (in microwave telescopes) the cosmic background radiation just where it should be, at just the frequency that was predicted if there had been a big bang (note the prediction was made in 1948, but the microwaves were not measured until 1965).
3) We can see gas clouds in the far distance (12 billion light years), which we see as they appeared 12 billion years ago, which are made of hydrogen and helium in the proportions that we expect would have been made in the big bang, and without the heavier elements that we think would not have been made in a big bang, and there is no other theory that has been able to explain the proportions of the light elements.
4) The way galaxies and quasars are distributed and the way they appear to have developed over time matches what we think would have happened if there had been a big bang (and rules out other ideas such as a steady-state universe).
You also asked:
You suggest we should be believers in this everything from nothing theory without the least bit of skepticism?
No scientist would suggest that you believe any theory without skepticism. Certainly, be skeptical! But skepticism is not the same as refusing to accept an idea just because it sounds far-fetched. If someone does come up with a better theory (where "better" = "makes predictions that match what we actually observe more closely and more efficiently than other theories"), then by all means, out with the old theory and in with the new. And it's certainly fine to attempt to poke holes in the current theory -- indeed, there is surely a Nobel Prize waiting for the person who proves that there was no big bang! But poking holes in the theory has to be done by either finding out that the theory contains contradictions, or finding that it fails to explain something that we can see happens in reality. One doesn't get the Nobel Prize for saying "that doesn't sound right."
Nobody has measured what a photon looks like even at 1 AU, much less at a light year.
We collect photons from millions of light years away every night -- they're called stars. Not to mention we've collected pictures of the outer planets (all are well more than 1 AU from us) both at distance via telescopes and up close via probes -- and yep.. photons still look like photons out there.
Now you could go ahead and try to claim that we have no 100% proof that those stars and planets are as distant as they appear to be but your argument would have to be strong enough to counteract standard candles, gravitational lensing measurements and even simple triangulation (the earth's orbit around the sun is wide enough to triangulate plenty of the nearer stars' distances) and any other distance measurement techniques I'm not thinking of. Oh, and you'd have to account for the probes managing to go where we told them in the case of the outer planets having different photons.
"gee, the experiment doesn't match our prediction, so our prediction was wrong."
That's exactly what they do say. But its generally preferred to modify an existing somewhat working theory to match the new data over dumping it all and starting from scratch. In this particular case, adjusting certain factors in the less well known areas of our theories (expansion rate of the universe) was a hell of a lot simpler than trying to rebuild things that are fairly well measured experimentally (the speed of light, for example.) Not that it doesn't happen (string theory isn't a direct take off from quantum mechanics for example -- they share properties of course because they're trying to describe the same things but the math of strings is pretty different from that of points) but outright replacement is not usually the first choice.
Overall, its absolutely true that cosmology still has a long way to go. But to claim that they're total crap for not having figured out 100% of everything yet is kind of missing the whole point of research.