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2answers
91 views

How does measuring redshift make us conclude that rate universe expansion is accelerating?

The universe is expanding in all directions. We can detect this by the redshift of electromagnetic radiation from other galaxies. We detect a larger redshift in galaxies which are further away, and ...
1
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1answer
52 views

Our universe the surface of a 4-dimensional sphere?

The cosmic microwave background that we observe uniformly around us is usually explained by assuming that our universe is the surface of a four dimensional sphere. That way the uniformity makes sense ...
0
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0answers
19 views

total amount of energy in the universe [duplicate]

What is the total amount of energy in the universe? is there the same amount of energy as negative energy, cancelling each other out? Or is it something different?
0
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1answer
29 views

Can we know full complete cycle of universe? [closed]

Can we know whole cycle of universe because without knowing full cycle we can't predict future perfectly so if we know full cycle we can predict perfectly like we know before experiment of chemical ...
0
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0answers
33 views

Is Dark Energy Pushing Us Or Pulling Us? [duplicate]

This may seem silly, but how do they know that the effects we are seeing from dark energy, (which we only assume must be there due to observed acceleration), are not from gravity pulling us out from ...
4
votes
1answer
33 views

Open Big Bang-less universe?

This came up in discussion around a class I'm taking. For a Universe with $\Lambda$ and matter contributions to energy density (and implicitly curvature, but no radiation), can you have a universe ...
1
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3answers
97 views

Is the universe flat?

There are more than one way to view the description of the universe as flat. There is the description of an open, flat or closed universe in terms of it's fate, expansion forever away from gravity, or ...
1
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1answer
52 views

Size of the Universe: Curved vs flat? Finite vs infinite?

I have recently heard the theory that the Universe may be smaller than observed but may be curved to the extent that light rays may have looped past us once already and hence appear to have originated ...
1
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1answer
24 views

Does the rate of expansion of the universe exceed the rate at which the local group is being pulled toward the Great Attractor?

I understand that the expansion rate of the universe driven dark energy exceeds the rate at which the local group is being pulled toward The Great Attractor (Hydra-Centaurus Supercluster). Does this ...
0
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2answers
61 views

How does “space” expand? [duplicate]

According to Big Bang theory and The Red shift theory "space" is "expanding". Keeping this notion of "space" as physically something in and of itself(space -time did not exist before The Big Bang); ...
0
votes
1answer
32 views

Is the Universe Past-Eternal?

Does the Borde-Guth-Vilenkin theorem definitively demonstrate that the Universe cannot be past-eternal, whatsoever? Does it not assume a classical space-time while the real world requires Quantum ...
1
vote
2answers
63 views

Can we observe an edge of the universe? [duplicate]

Firstly, I apologise if my thinking is completely incorrect - I am by no means a physicist (yet!), I have included layman illustrations to hopefully assist in explaining my thinking. I am imagining ...
0
votes
1answer
50 views

What is the mass of the universe?

Working with a flat and infinite model of the universe (which seems to be the most popular serious model these days), the density of the universe is 3e-28 kg/m^3 [1]. When added to the cosmological ...
5
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2answers
305 views

Light takes too long to get here

When looking at the night sky, we see lots of stars. Several places tell you that the light of those stars has traveled to many light years to reach Earth and there may be others where light has not ...
0
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0answers
117 views

If nothing can travel faster than the speed of light, how can there be parts of the universe we can't see? [duplicate]

Assuming we originated from a single infinitely dense point in space time in the big bang, how can there be parts of the universe that we can't see as the light has not reached us yet, if nothing can ...
3
votes
1answer
106 views

Many times speed of light [duplicate]

http://www.huffingtonpost.com/2014/03/24/theory-of-everything-big-bang-discovery_n_5019126.html What does "many times speed of light" really mean in this context? For a layman it's easy to draw wrong ...
0
votes
1answer
112 views

What's the meaning of the age of the universe?

I'm not asking about how we worked backward from an expanding universe to the age of the big bang, but rather what is the meaning of time in a near infinitely dense point in the context of general ...
2
votes
1answer
72 views

Where do our 4 macroscopic spacetime dimensions reside in multidimensional models of the universe?

In models such as M-theory with 7 'higher dimensions' plus the 4 macroscopic spacetime dimensions, where do our 4 macroscopic spacetime dimensions reside ordinally? My reason for asking is TV shows ...
-3
votes
3answers
155 views

What is the scientific view of creation? [closed]

Can space be created or destroyed? Is space conserved? I am not asking for matter,energy and time. Its just a question about conservation of space PS: I am asking for what was there before big bang. ...
0
votes
2answers
54 views

Direction of expansion of the universe

From what I understand the expansion of the universe has no "center". If we're flying through space away from the "center of the big bang", there's basically no way to tell. Every two given points in ...
0
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2answers
220 views

Did the singularity really existed in the begining of the universe?

I read in Hawking's brief history of time the following: The final result was a joint paper by Penrose and myself in 1970, which at last proved that there must have been a big bang ...
-4
votes
1answer
60 views

Is the universe a perpetual motion machine? [closed]

Is the universe a perpetual motion machine?
-1
votes
1answer
128 views

Can we have a static point in the universe? [closed]

Big bang theory states that the universe began from a single point (which we may consider as a central frame of reference for the objects in the Universe). In 1929, Edwin Hubble confirmed that the ...
1
vote
0answers
48 views

According to Penrose, Weyl Tensor=0 is the start/end of the Universe. Must it =0?

If I understand Roger Penrose's theory, as the Universe expands and cools, matter is consumed by black holes. Eventually the black holes collide and evaporate so that there is only energy and the Weyl ...
-3
votes
4answers
244 views

Was Einstein wrong when he said nothing can go faster than the speed of light? [duplicate]

If the universe is constantly expanding faster than the speed of light, how could Einstein be right?
3
votes
1answer
88 views

Is it possible that the universe in its entirety is discrete rather than continuous? [duplicate]

Since electric charge is comprised of discrete units and and mass is formed by discrete units is it possible that space-time itself is discrete as well?
1
vote
2answers
107 views

Initial conditions of the origin of the universe [duplicate]

I'm not quite sure this question fits the format of this site but I try to word it the best I can to comply the rules. The question is simple: How far can we go talking about the origin of the ...
0
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0answers
24 views

How is the scale factor from the FLRW equation used with Volume?

I'm trying to put a spreadsheet together that shows the co-moving volume of the universe from the time soon after the Big Bang through the present and then as predicted into the future. I am pretty ...
1
vote
1answer
55 views

Acceleration of the Expansion of Universe

Is the acceleration of the expansion of the universe (AEU) uniform in direction? Meaning that if a particular direction in the sky is chosen and the AEU is measured and then other directions are ...
1
vote
2answers
114 views

How can space expand?

How can space expand when it is only a perception of the separation between at least 2 objects. Isn't saying "space expands" implying it has properties?
-1
votes
2answers
64 views

A way to determine the exact location of the Big Bang?

See What is our location relative to the Big Bang?, which contains the following: The conclusion is that the Big Bang happened everywhere, all at once. Phys.SE users Ali and WernerCD reached this ...
2
votes
1answer
69 views

If we were able to double the mass of the ordinary matter in the universe it will recollapse?

What will happen if we suppose to be able to add mass at the universe? For example doubling the mass of the ordinary matter?
3
votes
1answer
99 views

Can a simulated Universe simulate Special Relativity

I know there are theories (or postulates) that hold that our Universe could be a simulation. I was wondering, if Special Relativity states that two events which are not causally linked can be judged ...
1
vote
2answers
62 views

Is there any mathematical structure modelling parallel universes (multiverse)?

Is there any mathematical structure modelling parallel universes (multiverse)? If we established such structure, is it science or science-fiction?
0
votes
3answers
121 views

Space and the size of infinity [duplicate]

If you could build a spaceship and keep travelling in one direction, what would finally happen? One answer is that you would never ever reach the end. But this sounds purely platonic space and comes ...
2
votes
1answer
30 views

Status of time in a Universe at maximum entropy

In billions and billions (thanks Carl Sagan) of years I have heard that atoms will lose energy and their temperature will approach absolute zero and thus their entropy will approach a minimum level. ...
14
votes
1answer
2k views

How can stars make up 0.5% of whole universe?

I was reading Wikipedia article about universe and stumbled upon pie chart which represents what universe contains. It says that stars make up 0.5% of whole universe. I tried to find average ...
2
votes
2answers
709 views

Can Flow of time become still?

According to theory of time dilation, flow of time slows down significantly at the speed of light.Is there any conditions practically or theoretically when flow of time is reduced to zero means it ...
1
vote
1answer
41 views

Ultra Deep Field 3D camera speed

I guess most of you saw Ultra Deep Field 3D video. In the end it shows camera moving in 3D perspective through all the galaxies. My question is, how fast is the camera moving in that video? I couldn't ...
5
votes
0answers
70 views

What coordinate system is used to describe planets positions in the universe?

How are planets positions described in the space and in respect to what? For example is Sun the origo and right now at this moment Earth has [coord_X, coord_Y, coord_Z]? or maybe [lng, lat]? ...
0
votes
1answer
50 views

Is there there is another universe which is made up of antimatter, in large amounts like ours is made up of matter?

Can it be possible that in the big bang, not one, but two universes were formed, one formed of matter, and the other formed of antimatter? It seems logical to me that since our universe is formed of ...
0
votes
2answers
96 views

What is the best explanation for the fine tuning of the Universe? [closed]

In my view, this is one of the most profound unsolved mysteries of Science. How to explain the fine tuning of the Universe without recourse to saying that a God/Designer did it. Examples of fine ...
1
vote
0answers
64 views

Modelling a matter dominated universe collapsing into a black hole

With the FLRW equations we can get solutions for a matter dominated closed universe in which the finale is an ultimate collapse, but this is only in terms of $a$ (the scale factor) and $t$ (time) and ...
1
vote
3answers
148 views

Does the Universe have finite number of particles? [duplicate]

I read that the number of atoms in the entire observable universe is estimated to be within the range of $10^{78}$ to $10^{82}$. Does the Universe have finite number of particles? If so, how could it ...
1
vote
2answers
229 views

Experimental proof for Conservation of Total Energy

In physics, the law conservation of energy states that the total energy of an isolated system cannot change—it is said to be conserved over time. (Source : wikipedia(conservation of energy) And ...
3
votes
1answer
240 views

What is the universe 'expanding' into? [duplicate]

We say the universe is expanding, and by expanding we mean the distance between objects gets larger over time. We call that "Metric Expansion of the Universe". So far so good. I kind of get the idea ...
1
vote
1answer
105 views

What arguments are in favour of an atomic structure to space-time?

The atomic theory as first theorised by Democritus has been successfully applied to matter and to energy (quanta). Space-time is still generally seen as a continuum. What arguments are there (if any) ...
1
vote
0answers
26 views

CMB radiation and holography

If in principle someone have the exact data of the CMB of our universe and unlimited computability power, to what extent it is possible to determine how the universe should look like? Does it fully ...
1
vote
2answers
60 views

Expanding universe and the peculiar velocity

Hubble's law states that the universe is expanding with a velocity equals Hubble's constant*distance from earth. But, recent findings show that the Andromeda galaxy is actually blueshifting towards us ...
3
votes
0answers
93 views

What is the theoretical geometry of bubble universes?

My research has led me to look into the idea of bubble universes which I don't know very much about. The first thing that I am looking for is understanding or visualising how could many bubbles ...