# Was the Universe massless in its first fraction of a second?

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Hi everyone. As this is my first post, I should say I am a retired non-scientist/mathematician, so I appreciate reasonably non-technical responses, please.

Richard Muller, “Now” (P.169) says: “In the initial Big Bang, before the appearance of the Higgs, all particles were massless.”

1. Is this the generally accepted view?

2. What about mass that is not dependent on the Higgs, would that have been negated by the extreme temperature?

3. I assume he is referring to a quark-gluon plasma. My understanding is that gluons are massless, but quarks have mass. Would that not apply in a plasma?

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Yes this is essentially correct. As the temperature is increased due to decreased volume. Ie reverse expansion.

The various particles reach a state of thermal equilibrium. They become in essence indistinguishable from a quark/gluon plasma state. Where all particles are massless. This is true of their associated fields.

The Higgs field is one of the earliest bosons to drop out of thermal equilibrium. However prior to electroweak symmetry breaking was also in thermal equilibrium.

Quarks wouldn't have mass prior to the Higg's.

Edited by Mordred

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Thanks Mordred. Wish I'd come here sooner, it's obviously a good place to get the kind of response I need.

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Yes this is essentially correct. As the temperature is increased due to decreased volume. Ie reverse expansion.

The various particles reach a state of thermal equilibrium. They become in essence indistinguishable from a quark/gluon plasma state. Where all particles are massless. This is true of their associated fields.

The Higgs field is one of the earliest bosons to drop out of thermal equilibrium. However prior to electroweak symmetry breaking was also in thermal equilibrium.

Quarks wouldn't have mass prior to the Higg's.

Quark-gluon plasma is hugely dense though isn't it, measured/calculated at some-exponential-number/g? How can it be massless?

Edit: Should have read your last sentence, which doesn't make sense to me because quarks are fundamental, aren't they?

Edited by StringJunky

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Fundamental particles aqcuire mass due to their binding energy with other fields.

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Fundamental particles aqcuire mass due to their binding energy with other fields.

It's a parameter that's added later?

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The next step in my thought process is:

A plasma has an energy structure. An energy structure has mass, (E=mc^2), but the extreme pressure and temperature would ensure that energy to mass transitions could not happen until expansion and cooling had kicked in.

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Your better thinking the full formula

$e^2=(pc)^2+(m_0 c^2)^2$ The reason being is this correlates the total energy of the particle not just the rest mass.

The particles total energy also correlates to the sequence (roughly) that particles drop out of thermal equilibrium due to cooling via expansion. Keep in mind the sequence isn't completely dependant on total energy but it is one of the factors.

Here you can get further details here

http://arxiv.org/pdf/0904.1556.pdf The Algebra of Grand Unified Theories John Beaz

http://pdg.lbl.gov/2011/reviews/rpp2011-rev-guts.pdf GRAND UNIFIED THEORIES

Chapters 3 and 4 in this article though cover the key formulas (Bose-Einstein, Fermi-Dirac statistics)

http://www.wiese.itp.unibe.ch/lectures/universe.pdf:" Particle Physics of the Early universe" by Uwe-Jens Wiese Thermodynamics, Big bang Nucleosynthesis

Edited by Mordred

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Thanks for the links. A quick glance tells me the maths will be way beyond me, but I'm sure I can pick something out.

BTW, I'm not very IT bright, either. The only way I can find this thread is by going via "My Content"; I guess I'm not navigating the forum properly.

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Thanks for the links. A quick glance tells me the maths will be way beyond me, but I'm sure I can pick something out.

BTW, I'm not very IT bright, either. The only way I can find this thread is by going via "My Content"; I guess I'm not navigating the forum properly.

You can click the View New Content button top right. If it's current it will be on the first or second page.

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Thanks; it worked.

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In looking for information on this topic I came across the “Yukawa potential”. I went to Wiki and the maths scared me! However, there is clearly a link between the Yukawa potential and the mass of quarks, but I suspect I’m out of my depth there. Is there a “hitch-hiker” level explanation?

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Unfortunately there is a lot of preliminaries to fully understand Yukawa couplings. Probably the best direction is to fill in the missing pieces. Unfortunately that will require study.

This article will help fill in the gaps as well as cover Yukawa coupling.

A more basic site though related but directly on Yukawa potential is

https://profmattstrassler.com/articles-and-posts/the-higgs-particle/the-higgs-faq-2-0/

Make sure you study each hyperlink in particular "What is a particle" and its wavefunction relations.

I'll try to dig up simpler approaches outside of textbooks (Quarks and Leptons) being a good one.

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Thanks for the links. I'll see what I can extract from the first one. Time is not in plentiful supply, so it will take a while; or I'll give up.

The link to Matt Strassler is familiar. In fact the "Responses" include an exchange we had a few years ago. I probably owe most of my knowledge of the Higgs to Matt.

If you do find anything at "idiot level", I would welcome it, but don't spend too much time/effort on it. There are going to be other questions.

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No worries, on my time lol, I always keep an eye open for entry style articles on advanced topics. Not for myself but to assist others.

The guidelines I use is to search similar styles to the introduction level textbooks which I lost count on how many textbooks I own Whether intro or advanced.

The unfortunate truth however is particle physics style is usually intense on math level. Particularly if you aren't good at calculus, Lie algebra (gauge groups), and differential geometry.

Which unfortunately 99% of the laypersons on forums simply aren't.

So even if you give up before I find those good articles on the topic, others may find it useful. So if you happen to find articles that work for you please share. Others may find them useful.

Edited by Mordred

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I have for some time been uncomfortable with the idea that the arrow of time is driven by increasing entropy.

Richard Muller, “Now” (2016) says:

“The key point is that in the early universe, the entropy of all matter was massless, thermalized particles, so it wasn’t increasing. If time’s arrow were truly being driven by the increase in entropy, there would have been no arrow. Time should have stopped. We never should have left that era. With stopped time, the expansion would stop (or never proceed in the first place).”

It was this that drew me into thinking about the entropy of the very early Universe. My thought was that time must have “existed” from the first instant, if not earlier, or there would have been no opportunity for the Universe come into being. It seems that Muller would agree with that, but is it in line with general thinking?

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It was the fact that I was also uncomfortable with Sean Carroll’s insistence on a boundary condition for the start of the Universe that I felt I needed a closer look at the start of it all.

If the Universe is evolving towards ever increasing entropy, it must have started in a low entropy state, and if so, how likely is that? Is Sean Carroll right that we have to assign some sort of boundary condition to the birth of the Universe, without which we cannot justify applying any kind of logic relating to the evolution of entropy?

The FLRW model describes the Universe in its first instant as a single quantum, containing all the matter and energy of the Universe, and completely filling the tiny space it occupied. When it expanded, it was not a case of the matter/energy exploding and moving outward. Its contents remained stationary relative to space, but became further apart as the expansion took place. In that first “quantum” matter/energy occupied all the available space; there was no room for manoeuvre; entropy could not have started evolving until more space became available.

Wouldn't that mean that entropy must have been at its maximum, and we don’t have to account for a mysteriously low entropy start?

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Hi everyone. As this is my first post, I should say I am a retired non-scientist/mathematician, so I appreciate reasonably non-technical responses, please.

Richard Muller, Now (P.169) says: In the initial Big Bang, before the appearance of the Higgs, all particles were massless.

1. Is this the generally accepted view?

2. What about mass that is not dependent on the Higgs, would that have been negated by the extreme temperature?

3. I assume he is referring to a quark-gluon plasma. My understanding is that gluons are massless, but quarks have mass. Would that not apply in a plasma?

I go with the others. Have no id about boson quarks and more

Edited by Tahir Gorgen