Inflaton, Mother of the Universe

quantalm writes "Forget the god particle, we're talking about the universe's particle mother. The theory of supersymmetry has rolled out two new ideas about the particle that puffed spacetime up from smaller than a proton to bigger than a soccer ball: it could be the 'unified particle' of Grand Unified Theories or a smaller-scale version that could be tested at the Large Hadron Collider at CERN."

Comments

inflaton?

[circletimessquare]

i don't know about unifying electromagnetism and gravity, but it seems like someone just unified economics and quantum mechanics

just tell us how to avoid the deflaton particle for the next few years

Re:inflaton?

[Monkeedude1212]

If those two particles meet, they don't cancel out - they actually cause a rift in the space-time continuum that is so catastrophic that it convinces people to take out sub-prime home equity loans.

Re:inflaton?

[istartedi]

So that's where the money went: Into subprime space.

Re:inflaton?

[SydShamino]

There might or might not be a $20 bill in my wallet; I won't know for certain until I look for it?

Re:inflaton?

[metamechanical]

Anyway just .02 cents.

OR PERHAPS $20! You won't know until you look.

Re:I love scientists.

[boowax]

I'm Sparticles!

Inflationary theory

[Kepesk]

I'm not saying that the inflationary phase of the universe is a false concept, but I've always thought that the way the theory came about is a bit sketchy.

Please correct me if I'm mistaken with any of this, but this is my understanding of its history. Earlier versions of the Big Bang theory did not include this rapid inflation in the earlier universe; the universe was said to expand at a more constant rate. However, when the Cosmic Microwave Background Radiation was first observed, there was no way to explain its irregularity based on that model. So physicists decided to plunk down a mysterious inflationary phase into their models of the early universe, a concept with no known cause or explanation, but which made the CMBR fit with the Big Bang theory. However, it's a concept that to this day they're still trying to reconcile with the rest of observed physics, as this article shows.

Could the theory be true? Sure. But if it is, it's because those physicists got lucky with their educated guess on the matter. Other theories with much more solid backing have in the past been roundly disproven.

Re:Inflationary theory

[Bigjeff5]

However, when the Cosmic Microwave Background Radiation was first observed, there was no way to explain its irregularity based on that model.

Actually you have that backwards, without inflation, the CMBR should be extremely irregular. There should be huge blotches of stuff all over. Think of a balloon filled with paint splattering on the floor - it doesn't create a fine coating all over the floor, it creates huge splatters here and there with huge gaps of nothing in between.

The CMBR, however, is extremely uniform. When you look at a picture of the CMBR, the variations in color are artificial (similar to the way the color nebulae from infra-red data) and represent extremely minute changes in radiation (you'll note there are no areas with no radiation, but there should be). The CMBR effectively shows a nice, even "coating" of radiation that covers the universe from one end to the other. This is disturbing, and cannot be explained by any physics we know of.

The only way to explain this is if the big bang wasn't an explosion (huge release, starts fast but decelerates quickly), but actually a controlled inflation - it had to start slow, accelerate, and then decelerate in order to produce the nice, even radiation we see. They had to accelerate the time-line of the Big Bang for a microsecond and then decelerate it immediately after in order to reproduce the uniformity seen in the CMBR. It's completely arbitrary, and has absolutely no grounding in physics, yet it's the only way to fit the physics we do know with the observations we see.

If you think you are disturbed by this, talk to a cosmologist or a physicist sometime. They absolutely hate having to change a model to fit observations without having any idea what is missing in their model to cause that change. It's like Dark Energy and Dark Matter, or the singularity of a Black Hole - cosmologists hate all of them. They use them, because it works, but they hate them all the same. They screw with their nice, neat physics.

Same thing with inflation - there is no known physical property that should cause inflation, yet inflation is the only way to explain the universe as it is now. It means there is something fundamental to the universe that we don't know or understand.

PS: Fun fact: if you tune an analog TV to an unused channel, something like 10% of the fuzz you see is caused by the CMBR.

Re:Inflationary theory

[bjorniac]

There are certainly alternatives to inflation that people do find attractive - ekpyrotic, cyclic or simply oscillatory universes for example can easily bring points into causal contact by extending the past of these points beyond where there would be a classical big bang. Various string models, and Loop Quantum Cosmology have methods for this (LQC has a really neat well understood bounce) and the idea goes back to Lemaitre's 'Phoenix Universe' ideas. However, inflation does more than just explain existing phenomena - it predicted a spectral index between 0.98 and 0.92, and COBE/WMAP bring it in at around 0.96. It also does a really good job of explaining structure formation. Now, that isn't to say that it's necessarily right, and that other theories couldn't do a similar thing, but inflation really does a good job. It's certainly far from perfect, numerous people have objections to it, but so far it fits the data we have.

Re:Inflationary theory

[bjorniac]

I should be clear: My experience is with scalar field inflation with a quadratic potential - the simplest models that are most common. Hybrid inflation can do almost anything, it's true.

My references for that statement:

Tegmark: http://arxiv.org/abs/astro-ph/0410281
Steinhardt: http://arxiv.org/abs/astro-ph/0507455

I believe Mukhanov and Turok both talk about it too, though I can't find the references easily at the moment.

Re:Inflationary theory

[h4rm0ny]

I should be clear: My experience is with scalar field inflation with a quadratic potential

The world needs a lot more people who say things like this. :D

Re:Freudian slip

[ruiner13]

Your mom is so inflated, your dad had to roll her in flour and find the wet spot.

Re:Has anything to come out of string theory ...

[sgt101]

I think that there are some really interesting predictions of how gravity should behave on a submicron scale which could rule out (or in) large number of potential string theories.

Of course, while I can imagine that gravity could be tested on a submicron scale when I start to try and imagine what kind of experiment could be constructed that actually did that I start to flail about and gape and make little clucking noises. I expect there are a fair number of physics fellas doing the same.

Re:Freudian slip

[Quiet_Desperation]

Your mom is so inflated, your dad had to roll her in flour and find the wet spot.

Nah, you need to go full on physics here.

"You mom is so inflated, your dad had to roll her up like a Calabi-Yau manifold and look for the Casimir effect!"

Thank you! Am I right? Huh? Huh? Am I? Huh?

Oh, shut up.

Brief(!) Explanation of Inflation

[bjorniac]

The "inflation" we're talking about here is the accelerated expansion of the early universe. So, first off why do we need it?

It turns out that parts of the observable cosmic microwave background are 'causally disconnected'. This means that you take two patches of sky as observed at the time the CMB formed (300k years after the big bang, we now think - approximately 15 billion years ago) and track their behavior back to the big bang. In the normal models where the universe is full of dust or radiation they never were in contact in the past: Light from one area could never reach another. Why is this a problem? Because they are remarkably similar. They appear to have come into thermal equilibrium (same temperature) yet this shouldn't be possible if they were never in contact. So we need to have a method by which the universe expanded faster before this period.

There are a few ways to do this - one is a cosmological constant. But the problem with a constant is that it's constant - we should still see it today, and we don't. The universe is not expanding that fast anymore - the bounds we can place on the cosmological constant today put it well below the effect we want from inflation. What we need is something that acts like a cosmological constant for a while and then drops away. This is what inflationary models are all about. The inflaton is a theoretical particle that starts off behaving like the comsmological constant, but eventually decays into the matter we see today. We model this by a particle moving in a potential - think of a ball rolling on the side of a hill. How the inflaton behaves is all about the ratio of its kinetic to potential energy - high potential energy looks like a cosmological constant, high kinetic energy looks more like normal matter. (I can explain this in more detail if anyone's interested). So the ball rolls down the hill, losing potential, gaining kinetic (there's also friction from the expansion of the universe so it loses 'energy' overall) and hence our inflaton does exactly what we need - slowly changing from looking like a cosmological constant to normal matter. In theory too, it decays once it reaches the bottom of the hill, but no-one provides much of a model for this.

This is old (20-30 years old is old in theory standards) stuff from Linde, Mukhanov etc. No-one would take it seriously, except that when you calculate things from it, it works incredibly well - it's the source of http://xkcd.com/54/ - it's still controversial. Some people love it, others think it's a fudge and doesn't do much for you. The new stuff here is that there is a method being proposed by which a multiplet of supersymmetric particles (again, I can say a bit more but it's not my field) is shown to be able to act like the inflaton. Ie a stable state of multiple particles bound together could act this way, and could be found at the LHC. Now, that's a lot of 'could' - the usual inflaton mass is set to around 10^12 GeV - way above what the LHC can reach, and this is the same across most inflationary models. But if the LHC can see evidence of supersymmetry (again, another discussion, but it is thought to be likely that if supersymmetry is real then the LHC will see it) it might be able to at least give some credibility to some of these models of inflation.