I was at a meeting in Princeton a short while ago, a small and focused workshop for people who are working on fundamental questions in inflationary cosmology. I hope to talk more about the meeting once the website is up (talks were not recorded), but here’s a simple question: what is the likelihood you would attach to the idea that some form of cosmic inflation occurred in the early universe?
My answer was 75%, which I thought was generous. It’s very hard to give a high probability to a speculative theory about what happened at energy scales to which we currently have no experimental access. But I found myself on the low end of opinions at the meeting, where the median was about 90% confidence. Of course, these are people who work on inflation professionally, and have chosen to do so. When I came home to ask the same question of my lunch crowd at Caltech, the answers were more like 25%.
An interesting glimpse into the non-unanimity of scientific opinion when it comes to untested theories. So, just for fun, let’s ask what your personal likelihoods are for the following theoretical ideas.
- Inflation
- Supersymmetry
- String theory
- Some form of Higgs boson
- Large extra dimensions
- WIMP dark matter
- Any non-cosmological-constant explanation for cosmic acceleration
I’m not defining these very carefully, and let’s posit that we’re not interested in weaseling about what the definitions mean. We’re asking what you think the probability is that, if you were to ask an omniscient being who knew everything about the workings of Nature whether these ideas were part of how the world works, would they answer in the affirmative. What do you think? (It’s helpful if you say a bit about what kind of perspective you are coming from.)
10% 1. Inflation
10% 2. Supersymmetry
1% 3. String theory
80% 4. Some form of Higgs boson
1% 5. Large extra dimensions
5% 6. WIMP dark matter
30% 7. Any non-cosmological-constant explanation for cosmic acceleration
undergrad in physics masters computational finance
Adam,
I think you are confusing supersymmetry with grand unified theories. Supersymmtry by itself has nothing to do with proton decay, although this is a generic feature of GUTs. Of course, there can be SUSY GUTs, where supersymmetry can play a role in the proton lifetime.
@Greg: Good job, thanks !
Looks like “popular opinion” is pretty much in synch with practitioners’ – though I guess readers of this blog would be much better informed than the “average layman”.
Inflation is very much top of the charts – which is great. In my (unqualified) opinion, its the only real advance in the cosmology & hep domain in the last 30 years.
Its interesting to see the huge standard deviation on string theory.
Looks like a case of “anybody’s guess” !
Honours Bsc physics student (final year)
1. Inflation – 80% for the general concept, much lower scores for any particular model
2. Supersymmetry – 60%, not necessarily low energy
3. String theory – 0% (rounded down from exp(-mass of the sun/planck mass)) as a final theory of everything (what does it even mean to say that, anyway?), 90% as a useful mathematical tool
4. Some form of Higgs boson – 99% if by some form you mean anything that does the Higgs’ job; whether its a single field with the mass and quantum numbers of the standard model Higgs I give more like 40%
5. Large extra dimensions – 2%, just because RS models are neat
6. WIMP dark matter – 33% (+33% axions + 33% sterile neutrinos + 1% modified gravity)
7. Any non-cosmological-constant explanation for cosmic acceleration – 5% – show me a model that is less pathological than a cosmological constant
1. Inflation 65%
2. Supersymmetry 0%
3. String theory 30%
4. Some form of Higgs boson 55%
5. Large extra dimensions 5%
6. WIMP dark matter 90%
7. Any non-cosmological-constant explanation for cosmic acceleration 90%
I’d rather a theory getting something from nothing or maintaining nothing for awhile from virtual somethings, than admitting things like singularities and the concept of infinity. Why? I know of somethings and absences of things but I have no experience of the infinite in any form. I am for emergent things and varieties and quite against infinite things or varieties. This is in the context of a physical theory, so I treat any sort of conclusion reached by taking limits or carrying out procedures ‘forever’ as being at best an approximation to a fact. I believe in space and time but not infinite space infinite time or infinitely divisible space and time. There is no such thing as the cardinality of the continuum in the real world, but there seems to be something like but, not exactly, the axiom of choice.
In the above light, inflation at least acknowledges the problem of something starting from a point of infinite density, and seems to be more of an emergent, i.e., familiar, explanation.
Supersymmetry. Borges said that the people of Uqbar abhorred mirrors for they multiplied the numbers of man. I think ultimate answers are way more subtle.
String Theory. I have no idea about it except that it seems to show a lot of possible ways to get around problems with infinities and singularities. Way more subtle than anything I can think of.
Higgs Boson. Yeah it’s out there in some form, but its discovery will do for particle physics what the arrival of the Phantom Menace did for Star Wars fans.
Large extra dimensions. Would be cool but cool’s not much of a criterion. Experiments so far negative on support for these rabbit holes, right?
WIMPS. These make some sort of sense since there are a lot of precedents.
Regarding 7, I think that once stars formed after the decoupling era, they generated plasmas of which not all constituents recombine. That is, more and more electrons escape into the intergalactic medium and more and more protons and heavier ions get stuck to electrically polarizable neutral matter in galaxies. The consequence is that galaxies are net positive charges that are repelled by each other through weakly screened Coloumb potentials, and this repulsive force grows so long stars burn in galaxies. So at present, the universe is in an electromagnetically dominant phase, and this phase began sometime after the formation of stars and not before their formation. This idea does not challenge General Relativity or nix the possibility of dark matter.
Inflation: 80%
Supersymmetry: 0%
String theory: 0%
Some form of Higgs boson: 20%
Large extra dimensions: 50%
WIMP dark matter: 20%
Any non-cosmological-constant explanation for cosmic acceleration: 50%
Inflation: 80%
Supersymmetry: 0%
String theory: 0%
Some form of Higgs boson: 20%
Large extra dimensions: 50%
WIMP dark matter: 20%
Any non-cosmological-constant explanation for cosmic acceleration: 50%
I’m a physics grad student.
Inflation: 20%
Supersymmetry: 1%
String theory: 1%
Some form of Higgs boson: 80%
Large extra dimensions: 1%
WIMP dark matter: 10%
Any non-cosmological-constant explanation for cosmic acceleration: 20%
I’m a physicist but not a cosmology or particle specialist. Working now in publishing, so with a broad rather than deep view – my answers are very much “intuitions”.
Great question Sean – maybe someone can do some “data visualization” on the replies! 😉
hep-ex postdoc.
Inflation: 90%.
Supersymmetry: low-scale, 40%. Some scale, 80%.
String theory: 70%.
Some form of Higgs boson: Some additional fields that trigger electroweak symmetry breaking, 100%. A remnant detectable scalar, 80%. A non-composite scalar, 75%.
Large extra dimensions: 2%.
WIMP dark matter: 40%.
Any non-cosmological-constant explanation for cosmic acceleration: 10%.
@TomC #138
Ha! How is the snow at chicago treating you and family?
Honestly though, I do think that rating “belief” by % is kinda hard, since I think a lot of stuff is a lot more nuanced that putting a hard and fast number on things. However, I totally do believe in putting a number in “Would you write a paper on these topics”, and the answer will be 100% for all!
(I blame Dan too.)
Inflation: 60%
Supersymmetry: 75%
String theory: 25%
Some form of Higgs boson: 80%
Large extra dimensions: 35%
WIMP dark matter: 75%
Any non-cosmological-constant explanation for cosmic acceleration: 50%
So who’s going to sum these all up?
I’m a layman who reads a fair amount of science “popularization” books and science blogs, and also forms my own opinions. (justified or not)
1. Inflation 35%
2. Supersymmetry 25%
3. String theory 5%
4. Some form of Higgs boson 35%
5. Large extra dimensions 10%
6. WIMP dark matter 50%
7. Any non-cosmological-constant explanation for cosmic acceleration 50%
The large extra dimensions seemed too vague to really answer. I mean the Standard Model has extra dimensions, right? And how large is “large”? I think it’s a certainty that any final theory will involve higher dimensional spaces – but whether or not they can be detected at scales larger than say, a hydrogen atom – that’s what I’m basing my 10% on.
Recovering elementary particle theorist here. The correct answers are:
1. Inflation – 75%
2. Supersymmetry – 10%
3. String theory – 0.01%
4. Some form of Higgs boson – 99.9%
5. Large extra dimensions – 0.0001%
6. WIMP dark matter – 80%
7. Any non-cosmological-constant explanation for cosmic acceleration – ??
Explanation at my website.
Physics teacher
Inflation – 80%
Supersymmetry – 90%
String theory – 50%
Some form of Higgs boson – 90%
Large extra dimensions – 1%
WIMP dark matter – 80%
Any non-cosmological-constant explanation for cosmic acceleration – 5%
Observational astronomer
Inflation – 20%
Supersymmetry – 20%
String theory – 1%
Some form of Higgs boson – 70%
Large extra dimensions – 1%
WIMP dark matter – 50%
Any non-cosmological-constant explanation for cosmic acceleration – 10%
So who’s going to sum these all up?
me, apparently 🙂
maybe someone can do some “data visualization” on the replies!
done!
likelihood of all the theories as given by all commenters
likelihood of all the theories as given by commenters with education/professional background in physics and/or astronomy
PhD hep-ph student
universal truth is not measured in mass appeal
http://www.youtube.com/watch?v=Igt-jW4e8ts
Graduate student: Theory group @ University of Texas
Also not sure why people have more confidence in String theory than in SUSY.
Each of these proposals confront real problems with current models. If any of them were really right, I think the horse would be in the barn by now. Since I am a member of the ultra-conservative fringe, I will give them all Easter eggs:
1.Cosmic inflation 0% – A new constant velocity solution for gravity perhaps
2.Supersymmetry 0% – Watch Olympic diving, easy to have multiple types of spin in one body
3.String theory 0% – Not a theory, an area of study that is not relevant to 3D space + scalar time
4.Higgs boson of any type 0% – find out in a few years, http://bit.ly/GEMtshirt says no stinkin Higgs
5.Large extra dimensions 0% – 3D space + time is MUCH richer than it is given credit
6.WIMP dark matter 0% – see 1, same solution would apply
7.Explanations of accelerated expansion not based on the cosmological constant 0% – GR is good, and will be replaced by something better, a variation on the only field theory better than GR, that of Maxwell.
I’m a layman with a lifelong interest in science and physics.
1. Inflation – 66%
2. Supersymmetry – 60%
3. String theory – 33%
4. Some form of Higgs boson – 55%
5. Large extra dimensions – 5%
6. WIMP dark matter – 5% I hate the idea of dark matter of all types
7. Any non-cosmological-constant explanation for cosmic acceleration – 15%
Question – are not inflation and string theory (in the form of M Theory and the hypothesis of an ekpyrotic universe) mutually exclusive?
I want to study Physics, I’m finishing high school and starting college this year 😀
1. Inflation 30%
2. Supersymmetry 10%
3. String theory 10%
4. Some form of Higgs boson 40%
5. Large extra dimensions 0%
6. WIMP dark matter 10%
7. Any non-cosmological-constant explanation for cosmic acceleration 0%
I am a lowly lay person with a math degree and an long time interest in physics.
To TRM (item 126), I wonder if John (item18) is John Moffat (and John’s book was interesting)
1. Inflation – 30%
2. Supersymmetry – 50%
3. String theory – 10%
4. Some form of Higgs boson – 80%
5. Large extra dimensions – 0%
6. WIMP dark matter – 50%
7. Any non-cosmological-constant explanation for cosmic acceleration – 0%
Nice poll, but the devil may be in the detail of definition. I know people who say inflation means the production of superhorizon perturbations, by which definition it is observed to be true beyond reasonable doubt. But did the universe go through a phase of vacuum domination, the physics for which requires no quantum treatment of gravity? That seems much more questionable, and certainly has little observational support. If we see significant tensor fluctuations in the CMB, consistent with the tilt of the scalar spectrum, that would be impressive – but the best-fit tensor fraction seems stuck at zero, so I think the probability of inflation must struggle to get to 50%. String theory seems a flexible enough theory that it too may end up true by definition (didn’t Schwarz say that any alternative theory would get called “string theory”?). But Bayes tells you you should adopt 50:50 odds in cases of ignorance, and that covers my knowledge of the maths of string theory.
1. Inflation – 30%
2. Supersymmetry – 60%
3. String theory – 50%
4. Some form of Higgs boson – 80%
5. Large extra dimensions – 1%
6. WIMP dark matter – 60%
7. Any non-cosmological-constant explanation for cosmic acceleration – 5%
Professor of cosmology, and textbook author.
1. Inflation – 95% (explains a lot, and just the kind of thing the universe would do at start)
2. Supersymmetry – 70% (in some form)
3. String theory – 80% (even if strings/branes are not “fundamental” but resonances of swarms of dissipating/regenerating “4-atoms” a la Anastassov & Petkov [see “What is the Electron?”, V Simulik ed, 2005] )
4. Some form of Higgs boson – 1% (hope not, or I lose a $500 bet with a well-known string theorist 😉 )
5. Large extra dimensions – 1% (their effects would have been observed by now)
6. WIMP dark matter – 1%
7. Non-CC explanation for cosmic acceleration –90% (in that a number on its own is not a satisfactory explanation, as others above have pointed out)
I’m not qualified to judge the likelihoods. I’m a multidisciplinary engineer. However, it seems to me that sufficient evidence exists to seriously doubt everything on the list.
Let’s start small and with impending evidence: I doubt the LHC will find evidence of the Higgs, and will thus set off a golden age of theoretical physics as the Standard Model is ripped to shreds.
Don’t take me for a creationist, though. The very fact that the Standard Model exists proves that humans can conceptualize beginnings without mysticism. Rock on, physicists who are smarter than me.