Questions tagged [matter]

Questions regarding a substance that takes up space, has volume, and has mass. Matter usually occurs in 5 forms, namely plasma, gas, liquid, solid, and bose-einstein condensate.

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1 answer
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How is observable matter distributed in the universe?

The observable matter in the universe is distributed and arranged into various structures, including black holes, stars, nebulae, and the much more diffuse regions of the inter-stellar and inter-...
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Stars, planets and galaxy motion [duplicate]

Is there any known planets or star systems in interstellar outer space that exist though not in motion?
2 votes
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Question re distribution of the baryonic matter in the Universe

In https://phys.org/news/2021-09-universe.html it says:"Scientists thus discovered some of the universe's missing baryons, thereby confirming that 80–90% of normal matter is located outside of ...
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What's the percentage of strange matter inside a star at any time?

Is there any amount of strange matter (or "top matter"?) inside stars? By strange matter I mean matter made out of flavours of quark other than up/down.
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Because the Universe is expanding, what is it taking up?

It is my understanding that the universe is expanding and that matter takes up space. While the universe only contains small percent of matter, wouldn't expansion indicate that the universe is ...
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1 answer
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What do "overdense" and "underdense" mean in cosmology?

“Overdense" and "underdense" often appear in various documents to refer to high density and low density respectively. And I know that "overdensity" is defined as $$ \delta(x)=\...
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Is the dark matter just regular matter out of the observable universe?

Could it be that darkmatter is actually the gravitational influence of regular matter that is situated out of the observable universe?
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Could matter be infinite?

Perpetual motion and Big Bang theory seem to allude that the universe can’t last forever because matter and energy are dispensed. Is it plausible the Universe has infinite matter?
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How does Hawking Radiation work exactly?

I know that a particle and anti particle, virtual particles, spawn at the edge of an event horizon, and one particle falls into the black hole, and the other goes out, but how does the other know how ...
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1 answer
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density of dark matter halo

I was surfing the net for knowing the actual density of dark matter halo for a particular Mh(Mass of the halo) and finally, I got two equations: for pseudo-isothermal halo and by NFW-profile So, ...
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3 answers
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Absorption of light by matter

What determines whether or not photons can be absorbed by matter? Intuitively, the answer is that a charged particle can absorb photons (whether it's positively or negatively charged), and neutral ...
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Transition of Domination in the Universe

While deriving the epoch of matter-radiation equality, we assume the transition from radiation dominated universe to matter dominated universe as instantaneous. But how instantaneous is this ...
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1 answer
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At the Big Bang, when everything was close together, why did it not "collide", violating Planck length or Pauli Exclusion Principle?

How could so much matter, or "all" in fact, have been concentrated in a smaller universe without being in the actual same place? Why did this not result in undercutting the Planck Length or ...
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How is the big bang a plausible theory? [duplicate]

In the Big Bang Theory, it is said that it started with a small speck of matter, yet we have an unimaginable mass of expanding universe which is assumed as immeasurable. If the theory of "Matter ...
2 votes
2 answers
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The Matter Anti Matter Asymmetry

The matter anti matter asymmetry is still a mystery that still can't be explained. But what if there wasn't an asymmetry? Isn't it possible that there was exactly equal amounts of matter and anti ...
2 votes
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Is the atmosphere of neutron star solid, liquid or gaseous state? [duplicate]

Neutron star has a thin layer of atmosphere consist mostly of hydrogen and helium and is about less than a metre thick on average, but what wasn't stated in many articles I read is the state of matter ...
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Formula to Compute sigma8 for correction in non-linear regime

I try to explain my issue on this forum since it seems to be appropriate. I need to apply a correction on $\sigma_{8}$ between linear and non-linear regime to keep it fixed (I make change the values ...
5 votes
3 answers
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Why isn't the black hole white?

I recently saw the first image of a black hole. As I understood, it is covered with bright, hot matter. In this case, how can we see the black disk (event horizon), instead of a bright disk due to the ...
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1 answer
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Scenarios: Abusing a black hole

So a black hole is this large, sphere-blob shaped fluid thing that distorts space and time, making a weird hole in space(even after 5 years, I still don't exactly get what a black hole is exactly and ...
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1 answer
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What was the process of calculating how much darkmatter/matter/dark energy the observable universe consists of and how did it come at this conclusion

In 2015 the Planck satellite consortium released an analysis of data collected by the Planck satellite that showed this percentage break down of the universe’s mass/energy. Ordinary matter: 4.9% ...
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Why more matter still left after collision with anti-matter?

Question implies all, why is that? Why we exist even after equally creation of matter and anti-matter, any possible exception?
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2 answers
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What explains the existence of energy/matter if it cannot be created or destroyed?

If the energy/matter that was contained in the singularity before the Big Bang had always existed, and if it’s true that energy/matter cannot be created or destroyed, then what explains its existence?
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6 votes
1 answer
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Do we know how old the matter that makes us is?

Last weekend, I had the pleasure of visiting an observatory where there was a series of lectures to cover up the fact that there was too much cloud cover to actually observe much at all. One of these ...
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6 votes
1 answer
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Why Helium could be produced in first minutes of big bang but not heavier elements

At what extent could be sure that no heavier elements than helium could be produced, if we know that matter in universe today is about 25% composed on helium, why could be so sure that the kind of ...
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Finding equation for energy density of matter

I'm trying to get an equation for the energy density of matter of the universe $\rho(t)$, assuming the number of particles is conserved and rest mass energy is much greater than kinetic energy. $\rho(...
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Is normal matter always accompanied by dark matter and vice versa?

Is normal matter always accompanied by dark matter and dark matter by normal matter? Was ever observed effect of gravity lensing without normal matter?
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What percentage of the hydrogen today has never been in a star

It stands to reason that some of the hydrogen and helium that formed directly as a product of the big bang might never have fallen into a star to re-ejected when that star explodes. My question is, ...
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Is there any proof of space being created?

Is there any proof for space being created? Because I guess an explanation for the dark energy (dark = our understanding of it) could be that there is a gigantic amount of matter/dark matter that we ...
1 vote
2 answers
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Are we made of stars we're seeing? [duplicate]

a fresh astronomy enthusiast here. Recently I've been reading upon how immensely far other stars are from our solar system and how is it possible that we may be seeing stars that are already dead. My ...
2 votes
1 answer
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What does an Einstein-De Sitter universe look like?

I know an Einstein-De Sitter universe is a "flat" universe, i.e. with a K ("bendiness", sorry, don't really know what to call it in English) factor of 0, but does that entail anything as to its ...
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1 answer
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TIME TRAVEL-Can it be really done? [closed]

Is it posssible for us to time travel? Is light essential factor or the dark matter and dark energy?
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3 answers
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Conversion of matter into antimatter

Is it possible that the intense gravity of a black hole converts matter into antimatter? Does this mean that matter or energy that goes inside the black hole is converted to antimatter?
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3 answers
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Could there be dark matter black holes?

Could dark matter compress and form black holes? Since dark matter is even more abundant than normal matter, a dark matter black hole should not be rare...right?
2 votes
2 answers
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If oxygen were pumped into space where would it go? [closed]

If an astronaut went into space with a sealed container of oxygen and opened it up in space and let all the oxygen go, what would happen to it? would it all just dissipate into some other particle or ...
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2 answers
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What are the differences between matter, dark matter and antimatter?

I thought dark and anti matter were kinda the same, but after saw a video, they mention that dark matter is not antimatter but their explanation is a little fast so I got doubts. What are the ...
3 votes
2 answers
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How much larger would a star have to be to cause thermonuclear reactions if it was made out of mostly rock like Earth, instead of gases?

I assume it would have to be considerably larger since rock isn't as flammable as gases are? But it's also more dense to begin with.. Do we know of any suns that are made like this? Is it even ...
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How does gravity interact with a photon?

If photon is mass-less and gravity can interact only with matter, then how does gravity alter the trajectory of light?
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3 answers
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When the universe expands does it create new space, matter, or something else?

I am wondering what exactly is meant when it is said the universe expands. Does it simply create new space for matter to fill, does it also create new matter/dark matter to fill that space, or am I ...
3 votes
1 answer
364 views

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 ...
49 votes
8 answers
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Does matter accumulate just outside the event horizon of a black hole?

My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last ...
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9 votes
1 answer
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Can a black hole reach a limit where it can no longer attract more matter?

Can a black hole reach a limit where it can no longer attract more matter? If so, what happens with that black hole? Does the black hole die? Does the black hole decrease its size?
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1 answer
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Black Hole, Object or Portal? [closed]

Some say that a black hole is a rip in space-time, a portal linking two points in the universe as one. How sound is this? I've read that when a giant star collapses, what is left behind (a massive ...
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2 answers
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Expansion again: where does the energy come from?

Is it sensible to ask for the overall increase in potential energy when looking at the baryonic mass in the universe moving away from each other, that is, moving against the direction of the force ...
9 votes
2 answers
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Neutrino interaction with dense molecular structures

Would dense molecular structures on heavier planets (crystalline or other compounds which are generally unknown to us) allow neutrinos to pass through as easily as on Earth?
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1 answer
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Where is all the antimatter?

The universe supposedly started off with equal parts matter and antimatter and they are said to annihilate each other. Also, nature is famous for it's balance between everything. So all we see is ...
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1 answer
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Are there any alternative explanations for the gravitational force we attribute to dark matter?

It always seemed counter-intuitive to me that we observed an measured a gravitational force and since the universe has not enough mass to account for it, the conclusion was to say there's a different ...
23 votes
7 answers
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Do we know the exact spot where big bang took place?

If you rewind the universe back 14,7 billion years, all matter were in one spot, and then started expanding. Do we know where this is in reference to our own solar system? And is there anything there? ...
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15 votes
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How does interstellar matter density vary?

Answer to my question partially answers this one, about density of intergalactic matter and matter within galaxy: But it is mostly a hot, ionized void. How void? The density of the intergalactic ...
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21 votes
1 answer
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Dark Matter Particle Candidates

Dark matter appears to dominate the matter component of the universe as compared to luminous, or baryonic, matter. Though it does not interact electromagnetically (it doesn't absorb, scatter, or emit ...
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