What is Early universe: Definition and 111 Discussions

As of now, it appears the ΛCDM can accommodate this new data but new data is needed to be sure. https://www.quantamagazine.org/standard-model-of-cosmology-survives-jwsts-surprising-finds-20230120/

I'm really curious about this, but I want to know how wrong I am. I've seen in a lot of content recently about how observations of early supermassive blackholes are observed to be more massive than they should be. If I understand it correctly it has to do with the maximum rate a super massive...

I have a question related to the uncertainty principle in QFT and if it is related to the early universe conditions. Do we still have four-vector momentum and position uncertainty relation in relativistic quantum theory? I have been following the argument related to the early universe and the...

Referencing this posted on the Webb thread: https://www.quantamagazine.org/two-weeks-in-the-webb-space-telescope-is-reshaping-astronomy-20220725/ So will they able to do spectroscopy on GLASS-z13, the galaxy dating 300M after the big bang? Do they expect to see any heavier elements in a galaxy...

In the detection of Cosmic Microwave Background Radiation I understand there's still some low frequency radio astronomy left to do before hitting the 'opaque universe' boundary where/when light could not propagate. What, if anything, can we still hope see?

Hi, Never done much cosmology but reading around I have found several sources saying the early universe (pre roughly 300,000 years) the early universe was full of gamma radiation. Since the universe has expanded this gamma radiation has been red shifted into the microwave region. Other sources...

Cumrun Vafa and colleagues have recently posted a new theory of the early universe in the paper: https://arxiv.org/abs/2009.10077 If anyone could explain the main themes of the paper in laymen friendly manner that would be really appreciated. In particular what is topological gravity ? how is...

I came upon a realization recently. The early universe is always described to have begun in a state of extremely low entropy and it's been increasing ever since. But the same amount of stuff exists now as it did back then. Only thing that's changed is how big the universe is now vs then. So...

It has been reported [http://www.astro.yale.edu/larson/papers/SciAm04.pdf, https://www.scientificamerican.com/article/the-first-stars-in-the-un/] that scientists have observed spectra of radiation emitted by quasars that date from about 900 million years after the big bang. Others have observed...

During the Planck Epoch was the universe in a pure state prior to the Grand unification epoch?

If in the early Universe the matter density was density so large causing an intense gravity field, was the time at that epoch running much more slowly compared to the actual time according to the GR? If so then, would any reference frame in the early Universe see the light apparently traveling...

Hello. Wannabe sci-fi writer here with what may be a simpleton's question. From Google et al: "It took 380,000 years for electrons to be trapped in orbits around nuclei, forming the first atoms. These were mainly helium and hydrogen, which are still by far the most abundant elements in the...

I came across this video today: Which summarizes this new paper from University of Tokyo: https://arxiv.org/pdf/1907.02273.pdf I get that the video is just an explainer for primordial black holes, but I was hoping to get a better explanation on exactly when conventional wisdom says density...

I don't think there is a thread on this? R Gusten et al, Nature, 2019, DOI: 10.1038/s41586-019-1090-x

A few years ago I became intrigued by articles reporting the discovery of stars very close to the purported Big Bang; 400 million years seems an awful short time for a star to evolve. Then more recently the discovery of 2nd generation - hydrogen, carbon stars - in the same proximity, supposedly...

I've been reading up on inflation, and have arrived at the so-called slow roll conditions $$\epsilon =-\frac{\dot{H}}{H^{2}}\ll 1\; ,\qquad\eta =-\frac{\ddot{\phi}}{H\dot{\phi}}\ll 1$$ I have to admit, I'm having trouble understanding a couple of points. First, how does ##\epsilon\ll 1##...

Does the relative density of the early universe contribute to the red-shift of distant galaxies? If so, by how much? How would this be calculated? Asked another way : Assuming both the early universe and the current universe are flat, could the relative difference of their space time metric...

What are the effects considered by the presence of sterile neutrinos and the early universe, and the neutrino decoupling era?

I have read that the early universe had a very low entropy. I don't understand why. A giant ball of plasma at billions of degrees K with particles moving in all directions. It seems like the definition of total disorder. Why is the entropy considered low?

Penrose's CCC model posits a mapping between our big bang and a future one. This is based on the idea than in the far future there will be no mass and at the big bang there was no mass. So in both cases the universe looses track of scale. I am aware that the idea of there being no mass in the...

Hi, I am new here. A while back I read articles about observations of supermassive black holes in the early age of the universe. What are the hypotheses that would explain how these black holes grew so large and so fast so soon? Could inflation play a role here? Like how inflation would be able...

Is knot theory taken seriously by the sconce community , This seems to be a novel theory which explains why our world is three dimensional. https://www.sciencedaily.com/releases/2017/10/171016190308.htm An international team of physicists has developed an out-of-the-box theory which proposes...

It is said that the imbalance of matter versus antimatter in the present universe implies CP violations at very high energy. It seems to me that it most directly implies baryon number nonconservation: If we assume (and I'm not exactly sure why this is a necessary assumption) that immediately...

Is there any comparison between the characteristics and the state of the QGP in collider experiments and in the early universe? Can one compare properties like temperature, pressure, specific heat, viscosity etc. using standard or non-equilibrium thermodynamics? Can one compare the...

In the early stages of the universe, before the formation of the first particles, did mass exist? If yes, what had mass? If no, can one say that the early universe was massless?

I often find that in books or lectures discussing the arrow of time and entropy and trying to explain how we have such complexity that the explanation is that when the universe was in it's early stage and was just a relatively small ball of apparently high entropy gas that it was in fact very...

Homework Statement Why does Thomson scattering occur in the early universe? Homework Equations $$ e^{-} + \gamma \rightarrow e^{-} + \gamma $$ is a Thomson scattering process if: $$ E_{\gamma} << m_{e}c^{2}$$ (Electrons are essenitally stationary) The Attempt at a Solution [/B] Very confused...

I've heard it said multiple times on here and elsewhere that as we "wind back the clock" of our Universe and the Big Bang that our laws of physics kind of begin to fall apart, in a sense. If this is true, can anyone explain exactly which laws become more difficult to work with, and why? Thanks.

https://phys.org/news/2017-01-cosmologists-closer-quantum-gravity.html Researchers from the University of Portsmouth have revealed quantum imprints left on cosmological structures in the very early Universe and shed light on what we may expect from a full quantum theory of gravity. Dr Vincent...

Will eLISA have the potential to detect early universe gws?

I have seen several estimates that the period during the early universe in which almost all the protons, neutrons, anti-protons, and anti-neutrons (P, N , AP, AN) were annihilated occurred about 1 second after the big bang. I conceptualize this as a period in which as the temperature cooled...

Dear All I have a project related to the early universe and general relativity. Can anyone suggest me a book to start with? Thank you

I was reading about the first few Planck seconds and noticed no mention of general relativity other than the horizon problem. I some googling and only came up with some 1979 research that took the assumption that gravity was less powerful in the past, which I find suspect and Was developed...

Why do quantum fluctuations of fields arise at high energies and temperatures? What is the mathematical formulation of these quantum fluctuations? Why are the sizes of these quantum fluctuations approximately the Planck size?

As I understand it, in string theory the constants of nature can taken on a huge different number of possible values and when the universe cools after the big bang these constants of nature get locked in as it were and become , well constants. My question is, what if we discard string theory -...

I have been reading through Mukhanov's book "Physical Foundations of Cosmology" and have reached the section where he discusses the process of reheating. In it he mentions that the decay of the inflaton into bosonic states can be "Bose enhanced", i.e. that if ##n## previously created particles...

I would like to study more about the notion of time in modern physics. In particular, I would like to understand better the following question: how does one measure the time in the early universe? To measure time one needs to have clocks. A natural choice to be used as clocks would be particles...

I just learned from an Astronomy course that when the sub atomic particles were not bound together, they were moving around freely, but after the universe expanded and cooled, they began to combine to form Hydrogen atoms. Now, before this combination period, the photons couldn't pass through...

We already observed it; it's too late to say it is too improbable. A particle from a star that exploded billions of years ago just went into my glass of water. But, if we ask the question before our sun blows up if a specific particle from it will land on the highest point of a planet 50 light...

I have heard before that for every 1 billion antiparticles there are 1 billion and 1 particles of normal matter. Has this been observed directly or just predicted? Have we only observed antimatter through its creation on earth?

A good year ago, quantum corrections have been proposed to the very early Universe. It was concluded that these quantum corrections contain a precise estimation for the cosmological constant and the so-called radiation term. The authors even have interpreted the latter as evading the big-bang...

Has the expansion of the Universe caused less clustering? If the expanding Universe is causing volume of space to increase, to me it would make sense that clustering would be impacted as a result of this.

I have on several occasions on PF flagged up examples where it appears that there is an age problem in the early universe, in other words highly evolved objects have been observed whose existences are difficult to explain at their high red shifts in the standard \LambdaCDM cosmological model...

Hey PF, Since there are stars that can be powered predominantly (>50%) by the CNO cycle, which requires carbon as a catalyst, and i understand the core temperatures of these stars is about 106 K. Does this mean that stars where the triple-alpha process is dominant (108 K) had to exist and die...

I do not have any education in particle physics, and I am trying to read the paper http://www.helsinki.fi/~hkurkisu/cosmology/Cosmo6.pdf . I would much appreciate some help regarding the specific questions below. The following is from the first page of the article. I gather that g is a count...

Dear all, Can anyone give me a time scale/ redshift range as an estimate for the formation of magnetic fields in the universe?

An interesting discussion at this conference here: http://physics.princeton.edu/cmb50/videos/20150612_session6_2.mp4 David Spergel said the next project should be to look for something called f and L or is is FNL? Can someone explain what this is and what its significance is? What did you guys...

All particle species are in equilibrium at early times of the universe. But I didn't find any book that makes the difference of kinetic and chemical equilibrium clear. I have some of my own opinions and I hope to get your comments: (1) kinetic equilibrium means the distribution function obeys...

Anyone have any insight concerning the latest research underway at Heidelberg University... concerning the "smaller than once thought" earliest stars? Any thoughts on why these 'smaller than once thought stars' also contain carbon, when at this early stage of star formation in a very young...

When temperature of the universe falls below nucleon mass ##T<<1## GeV, the number densities of nucleons (proton and neutron) which are in kinetic equilibrium can be obtained as ##n_i=g_i (\frac{m_i T}{2\pi})^{3/2} e^{\frac{\mu_i-m_i}{T}}##. Since baryon number should be conserved, then I...