# Tag Info

## New answers tagged space-expansion

0

It isn't said that galaxies don't move, or at least it isn't said by any physicists I know. Distant galaxies are moving away from us, and indeed their recession velocity can be (approximately) calculated using Hubble's Law. The question is why the galaxies are moving away from us, or more precisely is there a theory we can use to explain not only why ...

0

According to relativity and the modern belief in physics, it is said that everything depends on relative motion and nothing else This is not true. In General Relativity there is such thing as pecular velocity, the velocity relative to the local comoving frame. The galaxies have limited pecular velocity but their distance to Earth can increase faster ...

2

This isn't an answer, because I don't think your question has an answer, but it got too long to put in a comment. Anyhow, when physicists try to describe the universe we do it by constructing mathetical models. Then we use these models to calculate what will happen and do experiments to see if we we correct. If we got the correct answer it means our model ...

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The galaxies and (and binded objects) are maintained by gravity. The rest is explained here, Whats left at the center of the Universe after Big bang?

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The metric expansion of space is a fundamentally different phenomenon than the relative motion of two objects in the flat spacetime of Special Relativity: While special relativity constrains objects in the universe from moving faster than the speed of light with respect to each other, it places no theoretical constraint on changes to the scale of ...

4

Because space itself was expanding faster than the speed of light. Which is perfectly acceptable by the way with Special Relativity, because the speed of light is only a barrier for matter traveling through space. There is no such limit for the speed with which space itself can expand (or contract), as far as I know.

4

Gravitational red shift is due to the energy of a photon in a gravitational field. So the photon needs energy to escape the gravitational force and therefore the wavelength increases (redshift). The cosmological redshift is due to the expansion of the universe and thus is not connected to a gravtiational field. The wavelength of the photon stretches like ...

7

This is a rather lengthy answer as I tried to go a bit in depth; there is a short summary at the end. Will we see more or fewer stars with time? The short answer to this is: We see less stars with time, due to the fact that cosmic expansion is accelerating. Although what we really see at the relevant distances are galaxies; single stars are far too far ...

2

This is a really interesting question. I think the easy answer has already been given: Stars require lighter elements (Hydrogen, Helium) in order to generate energy (and hence light) from fusion. There is a finite (but thankfully enormous) amount of these lighter elements in our universe, all (in a "black boxed" sense) of which is gradually heading down ...

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Star formation will slowly start to decrease in galaxies as the universe ages because of the conversion of gas, such as hydrogen, into heavier elements, such as carbon and iron. Essentially the universe is slowly running out of fuel. Stars have a hard time fusing heavier elements. Eventually there will be no stars left. What will remain are black dwarves, ...

-1

If the age of the universe is $1 / H_0$, then as the universe gets older $H_0$ would get smaller. So theoretically the recessional velocity of distant galaxies gets smaller and you should see more. Of course observation falsifies $H_0$ getting smaller and thus the expansion models are falsified. Meaning the universe looks roughly the same at all ...

-1

I am probably sure that you have heard about how the sun is going to become a red giant over the next few billion years and later become a incredibly dense white dwarf.This concept applies for all stars of all the universe, not that they all become white dwarfs, but that they all run out of fuel at some point move into another star phase. There are mainly 2 ...

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Will we see more stars? The big bang blasted matter in all directions, resulting in the particles moving away from each other. These slowed down due to gravitation pull on each other. First forming small clumps due to their proximity, later with the clumps of clumps pulling together. This process keeps going recursively eventually forming stars, planets, ...

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I red some times ago about a scenario in which the number of visible objects is becoming smaller and smaller. This is basically due to the Hubble's law: the further two objects are, the faster they move away from each other and when the speed exceed the speed of light, no news can come from them any more. If you take into account that the expansion of the ...

1

Apart from the fact that the concept of relativistic mass is best avoided, as John Rennie mentioned, it is also a concept of special relativity: it can only be defined in an inertial frame (a Minkowski spacetime) where special relativity is valid. However, the expansion of space is a consequence of general relativity. There is no global inertial frame ...

3

You say: A distant quasar would be less massive in its frame of reference than our observations would suggest and this refers to the notorious expression for the relativistic mass: $$m = \gamma m_0$$ The trouble is that relativistic mass is a troublesome concept that causes more problems than it solves. For example, the gravitational field of a ...

0

To add to Stan Liou's point: No, it's not possible because we don't measure $\pi$ at all; rather, we define it in reference to Euclidean geometry, which is flat. However, Euclidean geometry probably has intuitive simplicity for humans because it closely matches the geometry of space in our environment. Here's one way of understanding explicitly what ...

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I read about Goodwin's "proof" that π = 3.20... Its BS and I know that. What I am wondering is whether his technique may have stumbled on something ( a warped space) years before Einstein. In short, no. Slightly longer, noooo.... Notably, even if Goodwin made some coherent sense (and he did not), doing this before Einstein is not a significant ...

-1

If a star Is 13.82 billion light years away It takes 13.82 billion years for us to see the Image so 13.82 billion + 13.82 billion = 27.64 billion years old because while that Image was flying through space, time was still moving forward also If I set up a camcorder telescope 1 light year away and look at earth then I can see the past on earth the closest ...

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