Questions tagged [early-universe]

Questions regarding the universe shortly after its formation, up to the CMB or even as far as the formation of the first galaxies

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Do black holes "store" ancient light?

The way I understand it, black holes have extreme gravity, and time moves more slowly in high gravity. For outside observers, it would seem that time would stop at the event horizon. Does this mean ...
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If Looking Into Space is Like Looking Back in Time, Why is it the Same in Every Direction?

After seeing the James Webb space picture, in which a tiny sliver of the sky the size of a piece of rice from our perspective here on Earth was examined and revealed contain, as expected, an abundance ...
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2 votes
1 answer
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Why is the CMB's redshift so high?

It is pretty well-established that the CMB was originally emitted around 380,000 years after the Big Bang, at a redshift of ~1100. The most distant known object is HD1, the light from which was ...
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Earendel and HD1; identifying population 3 stars and galaxies

Will JWST be able to tell if Earendel, a 12.9 billion year old star, is a population 3 star? Or do we already know from the current Hubble observations that Earendel is a population 3 star? I've read ...
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3 answers
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Gravitational time dilation

Did clocks run more slowly in the early universe due to gravitational time dilation? Or, alternatively, do they appear to be running more slowly when observed from today, if that is not the same thing?...
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How did pressure evolve in the (early) universe?

I am trying to derive how the cosmological pressure $p(t)$ evolved over time in the universe, especially in the radiation and matter dominated epochs. There are some very nice explanations how $H(t)$ ...
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Are features in the CMB correlated with features in the SDSS map of the most distant galaxies?

This is a follow up to an earlier question to which @pela gave an excellent answer. Apparently the statistics of the length-scales of the CMB fluctuations are similar to those obtained from other ...
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8 votes
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Is there any correlation between the Cosmic Microwave Background (CMB) and the distribution of distant galaxies?

The Cosmic Microwave Background (CMB) is remarkably isotropic but does exhibit a distinct dipolar Doppler shift and also much smaller but measurable fluctuations in intensity and polarization. ...
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2 votes
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How can a very old star be formed among Population III stars?

After looking at some articles about old stars, (this, that, and this Wikipedia article), I thought about how such an old and small star could have formed. As the early universe had very massive, ...
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3 votes
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What came first: Galaxies or Stars? [duplicate]

In Stephen Hawking's A Brief History Of Time, the book mentions that "in regions that were slightly denser than average...galaxies were born." (pg 123). However, according to many other ...
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What was there before the big bang [duplicate]

we know that our universe is expanding, but we must agree to the fact that it has a limit. It just cant expand till infinity. Eventually there will be a end to time. I thought alot about this and i ...
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2 votes
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430 views

What was the size of the universe around 400 million years after the Big Bang?

I was trying to find out how large the universe was around 400 million years after the Big Bang as this is when some of the first galaxies were formed but I am having trouble finding out the answer or ...
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1 vote
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657 views

Why is the Cosmic Microwave Background at the same distance no matter the direction we look?

I've read from different sources that: The CMB is visible at a distance of 13.8 billion light years in all directions from Earth, leading scientists to determine that this is the true age of the ...
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What was the absolute limit to the possible sizes of the first stars formed from "primordial material with no metals"?

This answer to Why don't or (can't) stars be more than 325 or so times the mass of the sun? What limits their size? includes the following: ...The upper limit you refer to is for compositions similar ...
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7 votes
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Cosmic Microwave Background Map

When a satellite takes measurements of the radiation from different patches of the sky to construct a map of the thermal radiation of the universe on the surface of a sphere, it would also contain ...
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Why is the Cosmic Microwave Background evidence of for a hotter, denser early Universe?

In his book Gravitation and cosmology, Steven Weinberg says that CMB makes it "difficult to doubt that the universe has evolved from a hotter, denser early stage". In my understanding, the ...
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2k views

Size of the Universe before the Big Bang [closed]

I can't understand how all the matter contained in the Universe, was contained in an area the size of a grapefruit before the Big Bang ? How could so much matter have been compressed in such a tiny ...
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11 votes
1 answer
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Will James Webb see Population III stars?

I have heard that James Webb will see the first stars that our universe produced. Can I assume that we may see galaxies that are so young that all of the stars in them are population III?
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16 votes
2 answers
672 views

Characteristics of the first planets in the Universe?

What would have the very first planets looked like, based on their most likely chemical compositions? For example: Were they mostly grey gas giants with atmospheres of hydrogen and helium, ...
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3 votes
1 answer
186 views

Could the Universe really be 12.5-13 billion years old?

My initial reaction is that "this must be wrong" and apparently that's a lot of people's initial reaction according to the article. https://www.nbcnews.com/mach/science/universe-may-be-billion-years-...
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3 votes
1 answer
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Question about expansion of space time

Was the expansion of space time during big bang uniform if so how come the stars and planets be formed because and matter as well as gravity would have been same everywhere
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1 vote
2 answers
203 views

How does science knows what is the early universe?

I've read about Hubble seeing the brightest quasar in the early universe. Question is, how does science knows what is early and what is late? Please correct me if I'm wondering, but after the big ...
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-1 votes
1 answer
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Field excitement in quantum field theory? [closed]

How at the beginning of this universe the fields as proposed in quantum fields theory get excited?? How exactly these fields originated?
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1 vote
2 answers
230 views

Why do we presume that the universe has always expanded?

When I read about the universe having always expanded from a 'singularity', I can't help but wonder if that is perhaps not the case. If a singularity is a point at which everything is infinite and is, ...
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9 votes
1 answer
198 views

Does the CMB pattern evolve in a human lifetime?

I was thinking, as CMB is a snapshot of a slice of the Universe during recombination, how much the cmb is changing with time ? I mean as we progress in time we look a CMB a bit more faraway each time, ...
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1 vote
1 answer
91 views

Who discovered the relation between CMB fluctuations and large-scale structure formation?

I haven't been able to find a reference to the first who showed that the small density fluctuations in the cosmic microwave background led to the formation of large scale structure as we know it.
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6 votes
1 answer
212 views

Portion of universe visible if gathering image from inflationary epoch

Apologies in advance for my over-exposure to pop science. I want to propose a telescope powerful enough to collect imagery from 10^-32 seconds after the “Big Bang”, or as soon as the end of the ...
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-3 votes
1 answer
157 views

Estimates VOLUME of the ur-Supermassive Black Hole of this universe

Assuming Prof. Poplawski's "universe in a black hole" ( and at Arxiv here ) concept is true--that our universe is the result of a nonsingular Big Bounce from a supermassive black hole (SMBH) under ...
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2 votes
0 answers
66 views

Question about finding energy density of a fermionic-bosonic gas

We know that energy density is given by this formula: $$u = \frac{1}{V}\int_0^\infty\epsilon_pf(\epsilon_p) g_s V/h^3 4\pi p^2 dp$$ Where $\epsilon_p=pc$ for relativistic particles. also $f(\...
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2 votes
1 answer
250 views

Primordial supermassive black holes. How old are they?

I know that astronomers have detected supermassive black holes in the early universe. What was the age of the universe at which these black holes were detected? In other words how long is it thought ...
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1 vote
2 answers
104 views

Expanding universe

If the first stars in the universe were formed 400 million years after the big bang, and the universe is expanding, should that stars at that time not been in our cosmic backyard? And should their ...
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6 votes
2 answers
443 views

Could the big bang have created super massive black holes?

I understand that space was compressed to a single point and that during the big bang all points within that expanded away from each other at phenomenal speeds. I also have heard that during this the ...
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2 votes
1 answer
143 views

Ionization Fraction of Helium in alternate, He dominated early universe

I'm asked to verify an expression for the ionization fraction of helium in a universe in which helium dominates baryonic matter. I'm given that the ionization fraction $X = \frac{n_{He^+}}{n_{He^+}+...
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7 votes
2 answers
832 views

How were the first stars formed?

In class, we read a Scientific American article, "Cloudy with a Chance of Stars" that explained how the cores and the dust around them formed stars(he called them eggs for a chicken/egg analogy, where ...
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0 votes
2 answers
208 views

What is the probability that we are the first ever intelligent life in the whole universe? [closed]

What is the probability that we are the first ever intelligent life developed all over the universe? Everything starts somewhere, Is there any probability that we are the beginners to be part of ...
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4 votes
1 answer
426 views

What existed before the big bang [closed]

What existed before the big bang? What all thing are there inside big bang object ?.
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30 votes
1 answer
6k views

Why didn't the Big Bang produce heavier elements?

Shortly after the Big Bang, temperatures cooled from the Planck temperature. Once temperatures lowered to 116 gigakelvins, nucleosynthesis took place and helium, lithium and trace amounts of other ...
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2 votes
1 answer
322 views

What is the meaning tiny bundle of energy smaller than an atom

At the beginning of a video on youtube titled "history of the world in 2 hours", it is said that "every thing begins with this tiny bundle of energy smaller than an atom". I want to know what it means....
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2 votes
1 answer
348 views

How could lithium burning take place in a quasi-star?

According to Begelman et al. (2008), one of the most distinguishing features of the hypothetical quasi-star is that it's supported by radiation pressure from the accretion disk of the black hole in ...
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4 votes
1 answer
194 views

Is it possible to get a glimpse of the Big Bang through gravitation waves?

I read in an article announcing the detection of gravitational waves by LIGO that it will be possible to detect them from the Big Bang. Is this true?
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0 votes
1 answer
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What was the entity/particle/state at the time of the Big bang?

At the time of the big bang if there was an original entity, what were it's attributes(if applicable) - mass, electric charge, color charge or spin? Can the current matter and dark energy together ...
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1 vote
2 answers
331 views

What happened just before the Big bang? [duplicate]

Does the CMB contain any clues to what caused the Big Bang? Does a mathematical model theorize it?
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3 votes
2 answers
627 views

Is time itself speeding up universally?

Time moves more slowly near a mass than in relatively empty space. For example, I get that an observer would see someone falling into a black hole to appear to move more slowly and get "stuck" on the ...
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2 votes
1 answer
111 views

How come, in our lifetime, we will see the first stars which ever formed?

Isn't it an unlikely coincidence that we live in such special times, that we will have observatories (JWST) that see all the way back to the first starlight in the universe? Are we dreaming, and is it ...
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3 votes
1 answer
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Mass distribution in the early universe

The latest big quasar find at ~12.8 bn LJ with an estimated mass of 12 bn M☉ (see e.g. http://www.newscientist.com/article/mg22530104.000-ancient-black-hole-had-an-inexplicable-growth-spurt.html) puts ...
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4 votes
1 answer
997 views

Big Bang / Big Crunch cycle?

I've been reading some of Stephen Hawking's work on the theory of the expansion (and ultimate contraction) of the universe and was curious if anyone has every hypothesized that the universe has ...
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2 votes
2 answers
256 views

Matter and Antimatter Interaction in the early Universe

Well it is said that during the Big Bang, things were created in pairs: one matter and one anti-matter. I think its a part of the Big-Bang Theory. It is also said that matter + anti-matter - Energy ...
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  • 123
2 votes
1 answer
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Time-density and time-temperature functions of the Universe since the Big Bang

I am looking for these... functions. I want to be able to say, "at a 1873. second there were around 54230000000 K temperature and 0.00435 kg/m^3 density". On the net I could find only tables or ...
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1 vote
3 answers
160 views

Could the universe have evolved differently?

Given the initial conditions at the Big Bang, could our universe have evolved any differently? In other words, did the initial conditions predetermine every stage in the evolution of the universe to ...
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-5 votes
1 answer
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Astronomy questions I wondered for hours [closed]

I read a question posted by a community member in my community that shocked me, I think it contains some pretty cool astronomy questions that I cant wait for you scientists to answer. I am asking this ...
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