The universe tag has no wiki summary.
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1answer
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Questions about the Jeans length
I have a couple of questions about the Jeans length. Suppose the universe has a homogeneous energy density, except there's a spherical region that is overdense.
I understand that if the region is ...
6
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1answer
136 views
Our Universe Can't be Looped? [duplicate]
With reference to the Twin-Paradox (I am new with this), now information of who has actually aged comes from the fact that one of the twins felt some acceleration. So if universe was like a loop, and ...
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4answers
298 views
Is there anything physically infinite?
I can't think of a single thing that could be infinite.
Because the universe is expanding, isn't it? But there is an ever-changing barrier, so why could there be anything infinite, both ...
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2answers
89 views
Is it possible that universe might not be speeding up expansion?
I'm not sure but I was thinking of galaxies shrinking with time while still moving apart from each other at almost a constant speed or less (i.e: uniform/slightly decelerating expansion). This may ...
0
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1answer
80 views
Is the underlying pattern of all dynamical physical processes in the universe actually chaotic? [closed]
After studying and pursuing research interests in chaos theory since the mid-1980s, I have to question whether standard physics (including all physical theories we currently use at all scales of size ...
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2answers
71 views
If everything in existence were increasing in size at some rate, would we be able to detect it?
Would our eyes observe any changes?
What about electronic measurement devices?
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2answers
84 views
Are all points in the universe connected?
Is it true that every point in the universe is connected or could be so theoretically? If so how is this mediated?
Is it through the quantum nature of the fabric of space or is it through the ...
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0answers
39 views
Has Time in the Universe been found to be Discrete or Continuous? [duplicate]
I have a question, has the Universe been found to come in Discrete Quantum, like Quantum Physics or is it Continuous in Nature?
I was wondering if time was like a Continuum, like the fluid in a soft ...
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0answers
62 views
Do we expect that the universe is simply-connected? [duplicate]
I heard recently that the universe is expected to be essentially flat. If this is true, I believe this means (by the 3d Poincare conjecture) that the universe cannot be simply-connected, since the ...
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1answer
47 views
Would the universe get consumed by blackholes because of entropy?
Since the total entropy of the universe is increasing because of spontaneous processes, black holes form because of entropy (correct me if I'm wrong), and the universe is always expanding, would the ...
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1answer
43 views
Could the outer structure of the Universe be made from Antimatter?
Cern recently stated that antimatter may be repelled by matter, much like the opposite effect of Gravity. So is it possible that antimatter is actually repelled to the edges of the Universe to create ...
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2answers
112 views
A question to the theory of multiverse
Guys I couldn't catch a point of multiverse theory..
Theory: If space-time goes on forever, then it must start repeating at some point, because there are a finite number of ways particles can be ...
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3answers
81 views
Acceleration in the rate of expanansion of the universe due to weakening gravity?
Could the acceleration in the rate of expansion of the universe be due to the weakening of gravitational forces, as the distance between objects continues to increase?
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0answers
24 views
If we find a way to simulate a universe, are we likely to be living in a simulation? [closed]
If we eventually find a way to use quantum computers to simulate the creation of a consistent universe, does that prove that we are extremely likely to be living in a simulation?
0
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1answer
49 views
Is dark matter expanding the universe, and creating the structures within it?
If dark matter repelled other dark matter, as well as regular matter(atomic or celestial), and regular matter were repelled by other regular matter "less" than by the dark matter, would not this ...
0
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3answers
113 views
Cosmological redshift interpretation
Can the cosmological redshift be interpreted as atomic frequencies increasing by the scale factor as the Universe expands?
This explanation seems closer to the truth than the popular idea that a ...
0
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1answer
90 views
What is the curvature of an empty universe?
My calculations tell me an empty universe has hyperbolic curvature. Is this correct? If it is, can anyone help me understand why this is intuitively?
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1answer
66 views
How fast did hydrogen atoms travel when they were first formed in the early universe?
I can't seem to find any data on this, is it a known value?
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2answers
70 views
can we have a parallel earth made of dark matter?
In the sense that the two planets move together and has intelligent beings with their own forces and particles, but they just do not interact with (are invisible to) us?
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3answers
148 views
Can space expand with unlimited speed?
At the beginning, right after the Big Bang, the universe was the size of a coin. One millionth of a second after the universe was the size of the Solar System (acording to ...
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3answers
125 views
Universe to energy
Would it violate any known laws of physics to construct a universe containing no mass, only energy?
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2answers
124 views
If the universe is 3D, how is space-time like a “fabric”? [duplicate]
I have been taught that space-time should be viewed as a fabric and that objects with a large gravitational influence indent that fabric. My question is, if the singularity of a black-hole punctures ...
3
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2answers
174 views
What's the avarage temperature of the Universe?
I'm sorry if this was asked before but with all the stars and dark matter and all the other stuff, curently in the Universe, what's the avarage temperature of the Universe? Is it like extremely high ...
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0answers
58 views
Total positive charge in the Universe
In their last homework, some of my students miscalculated a charge to be $10^{20}$ C over a squared meter and I was wondering if there was as much positive charges in the entire Universe. It would do ...
2
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1answer
128 views
What determines the end of space (universe)?
What determines the end of our universe?
Is it defined by the farthest out physical object or is it defined by the farthest out form of energy like light?
3
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3answers
179 views
How do we know for certain that space is expanding?
How do we know for certain that space is expanding?
Let's say that in the year 1950, we observe that galaxy 1 is 5 billion light years away from us and galaxy 2 is 10 billion light years away from ...
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3answers
119 views
Looking out into the universe means looking back in time - how does that work?
This is a question that has been gnawing on me for many years now. Back a long time ago, as I recall in reference to a scene in a popular science show on TV, I was asked the following.
The claim is ...
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1answer
75 views
Is there a relation between supersymmetry and entropy?
Considering that entropy denotes the level of order/disorder in a system, would it be possible for entropy and supersymmetry to exist at the same time? Or, are they entirely unrelated?
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1answer
171 views
Size of the Observable Universe [duplicate]
I wanted to know what the observable universe is so I was thinking and I thought, it must be age of the universe times 2.
Well I was wrong. I found on one website that it is 46B LY across in each ...
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1answer
51 views
Why there is so much “nothingness” in the Cosmos?
I mean look how big is the Cosmos and hof few planets and suns are outthere, compared to the vast "nothingness" between them.
With "nothingness" I mean no standard particles like atoms, electrons ...
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1answer
78 views
Speed of Universe Expansion [duplicate]
How much is the universe expanding every second (Earth second)?
If you could be a bit simple in the answer that would be good.
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0answers
46 views
Flung out of the galaxy
I watched a video by Dr. Michio Kaku, in which he states a theory about Dark Matter.
This theory says that Dark Matter could be just ordinary matter from another parallel universe, which would be ...
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1answer
63 views
What is the age of universe? [closed]
As we know at the time of big bang as mentioned by the scientist the universe expanded faster than the speed of light. So does it mean that at that time all the particles present travelled in the time ...
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1answer
72 views
Antimatter in the universe [duplicate]
Is it possible that some parts of the universe contain antimatter whose atoms have nuclei made of antiprotons and antineutrons, sorrounded by antiprotons? If yes what can be the ways to detect this ...
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2answers
100 views
How/why can the cosmic background radiation measurements tell us anything about the curvature of the universe?
So I've read the Wikipedia articles on WMAP and CMB in an attempt to try to understand how scientists are able to deduce the curvature of the universe from the measurements of the CMB.
The Wiki ...
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1answer
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In the big crunch theory, when the big crunch singularity forms, can the resulting black hole decay through hawking's radiation?
I've been pondering about this and I couldn't really find the answer for this. The big crunch theory postulates that the universe will eventually stop expanding and reverse back in on its self into a ...
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25 views
Where is universe expanding? [duplicate]
According to many physicist space, time and universe came to existence after the big bang. The universe is now expanding since after the big bang continuously. So my question is where our universe id ...
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2answers
115 views
Is this a great flaw in big bang theory? [duplicate]
Einstein said that, Time & Space cannot exists without one another. Big bang says, time didn't exist before the big bang. So the Primordial ball referred in the Big Bang theory didn't had any ...
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0answers
44 views
Is the speed of light the ultimate speed limit? [duplicate]
As we all know nothing can go faster than the speed of light as mentioned by most of our pioneer's in physics. But as I was listening to one of the statements of Sir. Stephen Hawkins he stated that at ...
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1answer
109 views
acceleration of the universe
Moments after the Big Bang, the universe was expanding at an incredible rate, (I've heard) faster than the speed of light. Due to dark energy, scientists predict the rate of expansion will pick up ...
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3answers
282 views
Could a universe with purely Newtonian mechanics exist?
I've heard about the fine-tuning principle and how if the fundamental constants of the Universe were changed even a slight bit, life could not exist as we know it.
However, study on this subject ...
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1answer
109 views
Finite amount of matter and space
(Please bear with me.)
If the universe included multi-universes, and black holes transferred matter between them, AND yet there was a large, but FINITE amount of matter and space, How would that ...
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1answer
114 views
Universal expansion faster than the speed of light
If the universe is expanding faster than the speed of light, and force carrier particles move at the speed of light, wouldn't this cause infinite universal expansion? Since no forces would be acting ...
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1answer
99 views
How would it be to look at the sky if the earth were near the edge of the universe?
By looking at this picture:
http://earthspacecircle.blogspot.com/2013/01/earths-location-in-universe.html
The earth is near the center of the universe. I've read that the universe look the same no ...
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1answer
127 views
Is the idea of dividing the universe into particles anything more than an untrue convenience? [closed]
In theory, we speak of a particle as having properties.
In reality, the measurement of any property is just an interaction between the target to be measured, and the measuring apparatus, where the ...
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5answers
481 views
Does the amount of gravitational potential energy in the universe increase as it expands?
It seems to me that extra gravitational potential energy is created as the universe expands and the distance between massive objects such as galaxy clusters increases; this implies that energy is not ...
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0answers
37 views
In the αβγ cosmology paper, how do the authors assume the integral of density over time in the early universe?
In the famous Alpher-Bethe-Gamow paper, the authors say: "it is necessary to assume the integral of $\sigma_n dt$ during the building-up period is equal to $5 \times 10^4 \frac{\text{g ...
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2answers
158 views
Total Energy of the Universe?
I've heard the total energy is zero, but I've also heard it cannot be said to be zero since there's so much unknown stuff in the universe. Is that true?
8
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1answer
170 views
Dumbed-down explanation how scientists know the number of atoms in the universe?
It is often quoted that the number of atoms in the universe is 10$^{70}$ or 10$^{80}$.
How do scientists determine this number?
And how accurate is it (how strong is the supporting evidences for ...
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1answer
162 views
Parallel universe and Infinite monkey theorem [closed]
Is the Infinite monkey theorem helpful for determining the existence of the very same our universe somewhere else?
