Questions tagged [observable-universe]
Questions regarding the region of space containing all the objects that we can detect using any method of observation.
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What Parts of the Observable Universe have we Observed?
Everyone talks about how big the observable universe is, all of the complexity, etc... But what parts of the observable universe have we actually seen? What Parts are hidden in relative shadows? Is ...
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Can the gravity of objects entering the observable universe be detected?
As time passes, we will be able to see objects that are further away, as their light eventually reaches us. Since gravity also travels at the speed of light, would we be able to detect when a super ...
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Could the redshift of all incoming photons be explained by a massive ring of distant masses pulling the sources of the photons away?
ChatGPT and wikipedia have informed me that the primary evidence for the theory that the universe is expanding is the fact that photons that arrive to our planet from all directions are being ...
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What is the rarest stable element in the universe? [closed]
I am making a hard sci-fi game with a focus on realism, in this game there is a need for a hard element to base money off of. Similar to how gold is used on earth.
I know there are lots of elements ...
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where are we in the universe as compared to the observable universe? [duplicate]
For distant galaxies to be accelerating away at equal speed in every direction, Earth would have to be at the centre of the universe. Since it is not, some region of the distant galaxies should appear ...
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Conditions in the Early Universe
I am interested in how the large-scale properties of the Universe change over time.
Does anyone know a trusted website which gives the temperature, density and radius (distance to the particle horizon)...
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Size of the whole universe if it were spherical
Suppose the universe is spherical and its density ratio is
$\Omega \leq 1.00125$
$\Omega = 1.00125$ is approximately the maximum possible value of the density ratio according to the Planck Mission ...
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Other Hubble spheres with no Lorentz symmetry?
Perhaps this may be a stupid question but anyways here it goes...
If the Lorentz symmetry is not global but rather local, wouldn't that mean that is possible that other Hubble spheres outside our ...
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When Only 50% percent of the sky will be filled with stars?
Answers to Approximately what percent of the sky has nothing in it? seem to suggest that with enough depth, we will finally hit something hence the sky is basically 100% full for any given resolution. ...
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Approximately what percent of the sky has nothing in it?
From my persepective here on Earth, the sky seems to look like a few large-ish things and a bunch of tiny things. Hubble teaches us that even the apparent void between the tiny things has many very ...
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Would an observer standing at the edge of the "observable universe" perceive the expansion of space-time?
I got this bizarre idea in my mind, after reading SCP-3321
There, as a person gets teleported through a wormhole, ends up at the edge of the Observable Universe, 46 billion light-years away from Earth....
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Are there any binary red supergiants?
I wonder if we ever have identified or observed a pair of binary stars (red supergiants). And I also wonder what would happen if they exploded, (theoretically) as we haven’t observed it. Also, would ...
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How do we know universe is expanding and not light slowing down? [duplicate]
We tend to take some things for granted, for example the light of speed is constant, but what if it isn't? How can we know that light is not slowing down at great distances for example, or that light ...
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Is there anything currently 46 billion light years away from Earth that we can see?
If the oldest galaxy ever discovered, i.e GLASS-z13, is at a present proper distance of around 33 billion ly from Earth, why then do we define the observable universe to have a radius of around 46 ...
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Does "Angular Diameter Turnaround Point" solve the Great Wall Problem?
According to Wikipedia,
The Hercules–Corona Borealis Great Wall is the largest known structure in the observable universe, measuring approximately 10 billion light-years in length.
But since it's ...
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How much larger will the "observable by us" universe be when JWST becomes operational?
Right now, using all our various current means of observing, we can "see" a sphere of X diameter around us. Webb will increase that to Y diameter. So our observable volume will increase by ...
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Is the solar system the only survivor of cosmic evolution? [closed]
A question has entered my mind, we know that all the phenomena in the universe are several thousand light years away from us, so the light we see from them is related to the past few years, now my ...
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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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Can we consider the Universe to be some kind of 3-sphere?
This is probably a naive question. I'm learning a bit of cosmology and I've recently covered the so called angular size-redshift relation, which states that in an expanding Universe the angular size ...
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How can the JWST telescope detect matter “shortly” after the big bang?
Since space is expanding, and accelerating, with distant locations accelerating at such a high rate that they are receding at greater than the speed of light, how can the Webb detect these distant ...
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If the ratio of actual total mass to critical mass (Ω) in the universe is only about 0.3, why do cosmologists believe it is flat, as far as we see?
What about astronomical observations makes scientists believe our universe is flat, at least as far as they can tell? Despite the critical Friedmann density being less than one, plus the existence of ...
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If we could fly off edge of observable universe what would happen? [closed]
If we could be at the edge of expanding universe in a fast space ship such that we could go beyond the edge, what does the science think we might experience?
Would we still be floating in space?
Would ...
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Can we observe galaxies after their recession velocity exceeds the speed of light? [duplicate]
It doesn't make sense to me that light could ever reach us from a galaxy moving away from us faster than the speed of light. But this video says that it can happen. Is this true? Could someone ...
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Logically, how can the universe be infinite in size?
Many people have told me that the “universe doesn’t care what you think” in my regards to it being infinite in size, and I know something that seems logical doesn’t mean anything when measured by ...
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Can we estimate the number of stars which have died in the observable universe?
We know there are currently between 10^22 and 10^24 stars in the observable universe, but can we make an estimate of how many stars have died so far? Or, in other words, how many supernovæ have taken ...
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Why would a quantity like the 'Hubble contrast' be squared, then have its square root taken?
From Sabine Hossenfelder's recent video, New Evidence AGAINST Standard Cosmology:
And her source....
Figure 2. The variation with increasing void radius of the variance of the Hubble parameter, the ...
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What defines Universe's Boundary? [duplicate]
We consider Heliopause as our solar system's boundary, Galaxy has its own boundary, certain theories says that there can be lots of universes, only when we define a boundary we can distinguish a ...
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Universe is a cluster of orbiting Galaxies?
Like planets orbiting stars, solar systems and other celestial objects orbiting a blackhole in the center of a galaxy, are the Galaxies and Galaxy clusters orbiting the centre of a universe (for ...
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Is quasar 2M1310-1714 outside the observable universe?
This Einstein ring
Image credit: NASA / ESA / Hubble / T. Treu / Judy Schmidt
shows multiple images of the quasar 2M1310-1714. Its distance is quoted at 17 billion light years and although the age ...
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How distant were the furthest currently-observable cosmic events when their currently-observed radiation was emitted?
(Edited for clarity. Thanks to James K and Connor Garcia.)
This question about the most distant, observable cosmic objects made me wonder if we know the distance that was between us and them at the ...
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How does the hypothesis of the "inconstant Hubble constant" solve the current crisis in cosmology?
It was published in a paper more or less like two months ago. I'd like to know also if more accurate measurements are necessary to close the gap between the model of the universe and the data reported....
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Volume of the observable universe [duplicate]
What about the volume of the observable universe?
Can we find it?
And what is the result in cubic light years?
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Is it "nonsense to even talk about" objects outside the observable universe not having gravitational influence on us? (finite speed of gravity)
In this supplemental answer to Is the zero gravity experienced in ISS the “artificial” kind? in Space Exploration SE I said:
Gravity moves at the speed of light so nothing outside out observable ...
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What are the one-dimensional observables that can reveal the matter clustering properties of the Universe?
As we all know, the distribution of galaxies, which depend on the spatial coordinates, can help us understand the large-scale structure of the Universe. We can measure the distribution of galaxies ...
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If we watched extremely red-shifted galaxies near the edge of the observable universe for a very long time, how would they change? Would more appear?
I have understanding sphere eversion as #1 on my bucket list (if I ever get a round tuit) but understanding metric expansion seems to be a rapidly receding possibility :-)
Question: Suppose it takes ...
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Can the other side of the observable universe be seen as a black hole?
When looking at the objects near the horizon of the observable universe, the objects seem to emit radiation that is red-shifted. Time seems to advance at a slower rate than our own and at the horizon ...
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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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How many galaxies are predicted in the observable universe? Does it contain dwarfs? Is there any size-ratio diagram?
According to quite recent research the observable universe contains about 2 trillion galaxies ($2 \cdot 10^{12}$). But what is counted there? Does this number also contain dwarf galaxies? According to ...
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Rotation of far away and near by galaxies
Do the far galaxies rotate the same as does the milky way and the near by galaxies?
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Eccentricity of Exoplanets
The field of astrobiology specifically discovering other planets that revolve around the sun-like star (also known as Exoplanets) has risen since 1990, but certain orbits of exoplanets are observed to ...
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How long does it take for a galaxy (or other object) to disappear behind the cosmic sight horizon?
After looking at this question, I am wondering, how long does it take for a galaxy or other space object, to disappear from our view from the Milky Way due to the expansion of the universe? Assume GN-...
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Is the age of the Universe really 13.8 billion years?
Ok, I know this has been asked by a lot of people, but my reason for asking this question is a bit different. Please read further.
I was watching a video by Fermilab (Start at 6:30, at 8:30 he ...
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Computing the over-density of Lyman-alpha emitters
Let's assume that I have observations of $N$ galaxies in a projected area $A$, within a redshift range $\Delta z = z_{max} - z_{min}$. What is the correct way of computing their number volume density? ...
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How far away are objects whose light will never reach us, because of the expansion of the universe?
I thought I had read this question on Stack Exchange before, but now I cannot find it... In fact, I thought I had posted this question before, somewhere, on Stack Exchange...
I believe the answer ...
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Why can't we point the centre of the universe from inflation graph we see?
This question is not about whether it makes sense to have a centre of the universe or not instead, it's about the inflation graph we used to see while describing the Big Bang. From the inflation graph ...
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Are the most distant known objects in the universe more than 14 billion light years away? [duplicate]
When I hear about the most distant objects in the universe, such as the recently discovered galaxy GN-z11, their distances are usually stated to be a little under 14 billion light years away....
But, ...
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How do scientists know that the distant parts of the universe obey the physical laws exactly as we observe around us?
How do scientists know that distant parts of the universe obey the physical laws exactly as we observe around us?
The question might look a bit odd but I am really stuck on my head. We know, ...
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How are younger objects outside our observable universe when the older CMB is an observer's temporal "edge"?
We know the observable universe is limited to objects whose light has had time to reach us and that an observer very far away will see a slightly different (assuming cosmological principle) observable ...
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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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How did we measure the mass of the universe?
In an wiki article, observable universe, it was mentioned that,
Mass (ordinary matter) 1.5×10^53 kg
I wonder how did we measure the mass of our observable universe?