Questions tagged [observable-universe]
Questions regarding the region of space containing all the objects that we can detect using any method of observation.
146
questions
2
votes
0
answers
84
views
Would we know if the universe was rotating?
I was wondering what we would observe if the universe had a small rotation. My conclusion was that galaxies on the equatorial plane of the universe would be slightly more redshifted than galaxies than ...
- 373
11
votes
1
answer
1k
views
How many individual extrasolar "shiny" objects has humanity identified?
Sorry, if this is a 'stupid' question of a non-expert, but this question came recently up in family discussion of mine and I couldn't give a satisfactory answer:
I know we have good (?) estimates of ...
- 281
-2
votes
1
answer
176
views
Why no Big Bang are happening now?
Why we are not able to see any Big Bang now? There is a possibility, I think.
Is it that Universe is so large that the probability of it's happening in the observable universe is almost zero, or is ...
- 21
0
votes
0
answers
89
views
How can the universe be 13 billion years old, but objects are seen farther away than that? [duplicate]
I keep running into this paradox, and the answers I get seem to be the same and not satisfying.
Most sites say the universe is about 13 billion years old, but we can see objects farther away, like 50 ...
- 109
5
votes
1
answer
799
views
Is there any way to detect the three-dimensional distribution of baryonic gas in our Universe?
As the title suggests, can the current observational techniques detect the 3D large-scale distribution of the baryonic gas, rather than just the gas within groups or clusters?
- 451
13
votes
1
answer
2k
views
As of now how much larger is our practically observable universe compared to just prior to JWST becoming operational
On April 2 2022 I asked for estimates of expected results. How much larger will the "observable by us" universe be when JWST becomes operational?.
As of Jan 27 2024 with JWST operational for ...
- 767
4
votes
2
answers
361
views
Was the Big Bang an event within a preexisting Universe, or did it mark the beginning of the entire Universe, beyond just the observable Universe?
Could it be that the Universe is truly infinite, and the Big Bang was merely a singular, specific event that resulted in the birth of a 'bubble,' i.e. what we perceive as 'the observable universe'? ...
- 51
0
votes
1
answer
50
views
Formula for rate of expansion of the universe vs distance?
How does the distance $r$ scale with the expansion of the universe?For example if $r_{o}$ is the distance between us and a galaxy and $V(r_{o})$ is the rate of expansion of the universe at that ...
- 21
21
votes
3
answers
6k
views
How can telescopes see anything at all?
I'm impressed that we have any telescope imagery at all. Take the images we have from the "Pillars of Creation".
The Pillars of Creation is in the Eagle Nebula, some 7,000 light-years away ...
- 353
0
votes
1
answer
126
views
Is the universe still considered "finite but unbounded"?
The BBC reports in Alien life in Universe: Scientists say finding it is 'only a matter of time' that Scotland's Astronomer Royal, Catherine Heymans, has said
We live in an infinite Universe, with ...
6
votes
1
answer
151
views
What natural astronomical object is rare on a Hubble volume scale?
There are some milestone objects on different scales of the universe.
The star is a notable feature on a solar system scale
The supermassive black hole is a feature on a scale of a galaxy
??
The ...
- 223
1
vote
0
answers
42
views
Has any astronomer/physicist used geometry and trigonometry to calculate where the center of the universe is? [duplicate]
Since we are pretty sure that the universe is expanding at a steady and accelerating rate wouldn’t it be possible to simultaneously observe 4 points (galaxies) that are all, as closely as we can tell, ...
- 21
1
vote
0
answers
75
views
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 ...
- 309
1
vote
0
answers
62
views
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 ...
- 79
3
votes
3
answers
1k
views
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 ...
- 231
1
vote
1
answer
780
views
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 ...
- 121
0
votes
0
answers
170
views
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 ...
3
votes
1
answer
260
views
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)...
- 371
5
votes
2
answers
349
views
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 ...
- 2,264
1
vote
1
answer
71
views
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 ...
- 1,017
3
votes
0
answers
120
views
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. ...
- 1,677
20
votes
5
answers
4k
views
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 ...
- 337
2
votes
1
answer
417
views
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....
- 2,668
3
votes
0
answers
98
views
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 ...
3
votes
0
answers
69
views
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 ...
- 31
10
votes
3
answers
8k
views
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 ...
- 657
5
votes
1
answer
402
views
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 ...
24
votes
2
answers
5k
views
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 ...
- 767
-2
votes
1
answer
105
views
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 ...
8
votes
1
answer
228
views
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-...
- 558
6
votes
1
answer
301
views
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 ...
- 3,926
2
votes
2
answers
145
views
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 ...
- 29
0
votes
1
answer
145
views
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 ...
- 5,307
-2
votes
3
answers
320
views
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 ...
- 123
1
vote
0
answers
49
views
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 ...
- 16.3k
4
votes
6
answers
6k
views
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 ...
- 59
7
votes
2
answers
683
views
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 ...
- 171
2
votes
1
answer
450
views
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 ...
- 5,307
0
votes
1
answer
154
views
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 ...
- 2,640
1
vote
1
answer
75
views
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 ...
- 2,640
4
votes
1
answer
326
views
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 ...
- 1,071
9
votes
1
answer
279
views
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 ...
- 175
6
votes
2
answers
187
views
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....
0
votes
0
answers
153
views
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?
4
votes
2
answers
398
views
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 ...
- 30.7k
2
votes
0
answers
54
views
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 ...
- 451
5
votes
1
answer
351
views
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 ...
- 30.7k
1
vote
0
answers
65
views
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 ...
1
vote
3
answers
619
views
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?
- 11
2
votes
0
answers
96
views
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 ...
- 245