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from the unterminated-strings-cause-inflation dept.
Submitted via IRC for SoyCow1984
Our universe: An expanding bubble in an extra dimension
According to string theory, all matter consists of tiny, vibrating "stringlike" entities. The theory also requires there to be more spatial dimensions than the three that are already part of everyday knowledge. For 15 years, there have been models in string theory that have been thought to give rise to dark energy. However, these have come in for increasingly harsh criticism, and several researchers are now asserting that none of the models proposed to date are workable.
In their article, the scientists propose a new model with dark energy and our Universe riding on an expanding bubble in an extra dimension. The whole Universe is accommodated on the edge of this expanding bubble. All existing matter in the Universe corresponds to the ends of strings that extend out into the extra dimension. The researchers also show that expanding bubbles of this kind can come into existence within the framework of string theory. It is conceivable that there are more bubbles than ours, corresponding to other universes.
Journal Reference:
Souvik Banerjee, Ulf Danielsson, Giuseppe Dibitetto, Suvendu Giri, Marjorie Schillo. Emergent de Sitter Cosmology from Decaying Anti–de Sitter Space. Physical Review Letters, 2018; 121 (26) DOI: 10.1103/PhysRevLett.121.261301
(Score: 2, Interesting) by Anonymous Coward on Sunday December 30 2018, @09:20PM (9 children)
I'm a physicist with a PhD.
i want money to go into fusion research and building a colony on Mars, not string theory and a bigger version of the LHC.
I want intelligent young people (i.e. grad students) to work on making technology more energy efficient, food production cheaper, and climate change mitigation schemes. I want them to build a space elevator so we can get off this rock already and establish self-sustaining colonies that won't be wiped out when asteroid/nuclear bomb or whatever happens.
I DON'T want them wasting their energy and getting high on highdimensional imaginationland.
I agree that the theories are beautiful and worth studying, but we have limited resources.
general relativity and quantum mechanics are incomprehensible to most people, and they are beautiful imaginationland births, but they were generated because there were EXPERIMENTS pointing to problems (photoelectric effect and conceptual contradictions between Newtonian gravity and special relativity). If your theory makes predictions that are, in practical terms, out of reach of experiments, then it's not a theory. it's just pretty math.
I will not agree to giving money for polock's "paintings", and I will not agree to giving money for string theory research.
if you as a private person want to work on it with your resources, or fund someone to do it, go ahead.
but I think society has better things to focus its money and labor on.
(Score: 4, Insightful) by johnlongjohnson on Sunday December 30 2018, @09:47PM (3 children)
Clearly you're not.
First off a physicist with a PhD would understand the applicability of fundamental research to each of the topics listed as "want".
Secondly you're posting AC.
Thirdly if you had anything above a high school diploma, you'd understand that the general public doesn't have to understand a theory in order to reap it's benefits. For example GR is why GPS shows you being home rather than several miles away. And you'd understand why QFT is absolutely fundamental to modern solid state electronics and upcoming spintronics. This list is actually endless so I'll leave it with those two.
Fourthly your definition of a theory without practical experiments being "just pretty math" is flat wrong. Math itself is an experimental tool. It is a way of exploring and experimenting with things that are beyond our current tech and it is precisely how we devise tests that might be physically realizable either now, in the past or in the future. For example Bell's inequalities in the 1960s leading to us being able to prove entanglement via Aspect et al in 1982 which has lead to huge advancements in everything from fiber optics to information theory.
The fact is string theory, M theory etc currently serve to inform modern QFT and GR researchers about which directions to look to expand their theories. And yes we do get predictions that are unrealizable or intractable under certain formulations of QM without tossing in M theory. For example AdS/CFT correspondence has been instrumental in solving the black hole information paradox. In that way, these theories serve as a short cut through the endless math in much the way that Feynman's path integral formulation and perturbation theory have served as shortcuts through the intractable infinities in earlier theories.
So yes it's math, and yes it's pretty.
But deciding you don't like a theory because disregarding it to focus on immediate practical applications, is now the cool hipster thing...
Well it just shows you're a hipster, and the inability to think beyond the now and perhaps the immediate future, shows you're probably a millennial.
Sorry to break it to you but fundamental research doesn't work that way.
(Score: 0) by Anonymous Coward on Sunday December 30 2018, @10:13PM
I made a point in distinguishing between GR and quantum mechanics, on one side, and string theory on the other.
I didn't decide I don't like string theory (in fact I would love to have the time to learn it properly). I am saying that we have limited resources, and currently our best and brightest are busy trying to solve a nonproblem. They have beautiful math that can describe everything, and absolutely no empirical method to pin down the description enough in order for it to be useful.
Either come up with a theory that is descriptive, or start working on other problems (that humanity is having), because the theory you have now does not describe the real world. At best, it describes many worlds and ours is one of them (and we have no way of telling which) --- which essentially means it's not a theory of our world.
Here's a different way to put it. It's wrong in the particulars, but mainly right: I have a opaque box with billiard balls inside.
You can make an infinity of correct theories of how the balls interact based on their color, all of them correctly predicting how the box reacts to outside inputs, all of them incompatible, all of them predicting different things that will happen when we finally have a knife sharp enough to cut the box. But if nobody is working on sharpening the knife, all of those theories are useless.
(Score: 0) by Anonymous Coward on Sunday December 30 2018, @11:16PM
You sound like the posters above who don't understand string theory so they claim it is false.
If you disagree with the PhD then mod the post "Disagree". But you can't claim the poster is not a PhD because s/he posted as an AC and you don't like their opinions.
(Score: 1) by khallow on Monday December 31 2018, @08:01AM
I have a PhD in math (area was QFT) and I mostly agree with AC. There's a difference between fundamental research and useless research.
WRT string theory, there's two things to keep in mind. First, it's incredibly cheap as far as research goes and does have some utility on the math side. On the former, the world-wide effort of string theorists is probably a couple of orders of magnitude cheaper than the LHC. Even if it never pans out as a physical theory, it's still making a positive contribution to our understanding of math approaches to this situation.
Second, where's the testable predictions? It's not fundamental physics research, if it doesn't have those predictions!
If only that were true. The cool hipsters seem to be on the other side of that particular argument. I've never seen a lot of people criticize the way science is done. It should be more than it is.
Back at you on that. This is the "throw money at the wall and find out in a few decades whether any of it stuck" strategy.
My view on this is that if you can't show any sort of near future benefit - which can include merely bettering our understanding of the problem, its math, etc. - then you're not doing research, fundamental or otherwise, you're just cashing checks.
(Score: 0) by Anonymous Coward on Sunday December 30 2018, @11:24PM (4 children)
"but I think society has better things to focus its money and labor on."
The amount of money society "wastes" is truly monumental.
Did you know some people consider space exploration a waste of money while others consider the whole sports industry a waste. Why not go after one of the huge wastes ... Like plastic shopping bags... Ban them and save $4billion/year
https://conservingnow.com/plastic-bag-consumption-facts/ [conservingnow.com]
(Score: 0) by Anonymous Coward on Monday December 31 2018, @12:18AM (2 children)
Clearly, people value having plastic shopping bags at more than $4billion, otherwise they wouldn't spend that on them.
That there might be externalities that you don't like and which would be mitigated by a legal ban doesn't mean you are saving $4billion, if just means you are using legal means to control other peoples' behaviour.
The correct method is to determine the cost of the externality and charge it to the people making and using the plastic bags, and then to use that money to correct the problem. That is the important bit.
If it is not enough money to fix the problem, you raise the tax on bags until it is. At some price point people will start using less plastic bags. At some further point in the ratcheting tax, the money collected will be enough to fix the problem.
(Score: 1) by khallow on Monday December 31 2018, @08:03AM
And if that change of behavior doesn't happen at a price point that reflects the real externality, then it's a solid indication to move on, the problem doesn't need to be solved any further.
(Score: 0) by Anonymous Coward on Monday December 31 2018, @02:18PM
You are going to need 1000% tax on a 10 cent bag to even get people to notice. It is incandescent lights all over again, the current inefficient product is just too cheap and as long as it is even available people will keep using it. The alternative is to bring your canvas bags or re-use the store's boxes (from incoming shipments). other countries like the Philippines have done bans and just like incandescents, the US will be one of the last countries to implement a ban.
(Score: 2) by RandomFactor on Monday December 31 2018, @02:11AM
Cost to retailers of $4 Billion/Year does not mean that eliminating them will save $4 Billion a year and could easily result in highers costs, pollution and carbon footprint.
More details here on Paper vs Plastic
http://www.allaboutbags.ca/papervplastic.html [allaboutbags.ca]
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