Hubble Law & SR: Does Velocity Increase Mass?

In summary, there is a concept of relativistic mass, which is now considered deprecated, and the more commonly used concept is that of invariant or rest mass. In a flat universe, distant objects appear to have a recessional velocity due to the Hubble law, but this does not necessarily mean they have gained mass relative to us. In fact, in the limit of a zero-mass density universe, relativistic mass is not a relevant concept. In the real world, the mass density is not zero and the use of Einstein coordinates means that relativistic mass is also not applicable.
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Arman777
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This question will sound mostly stupid but anyways.

We see that galaxies have some velocity due to the Hubble law. Let's take an object that has a recessional velocity of ##v##. In SR case assuming the universe is nearly flat, can we say that the galaxy gains mass relative to us ?

I guess in this case the velocity will be low so there won't be any relativistic effect ?
 
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Velocities can be high.
 
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Relativistic mass is a deprecated concept nowadays - "mass" is taken to mean "invariant mass", also known as "rest mass", unless otherwise stated.

The limit of a zero-mass density FLRW universe is Minkowski spacetime, equipped with a rather unusual coordinate system (Milne cosmology). In that case, distant test objects "at rest" in this system would be receding, but since you aren't using Einstein coordinates relativistic mass isn't a relevant concept (even if it weren't deprecated).

And in the real world, the mass density isn't zero, so you have curved spacetime and again you can't use Einstein coordinates. So once again, relativistic mass isn't really applicable.
 
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I understand it thanks for your reply
 

1. What is Hubble's Law?

Hubble's Law is a fundamental principle in cosmology that states that the farther away a galaxy is from us, the faster it is moving away. This relationship between distance and velocity is described by the equation v = H0d, where v is the velocity, d is the distance, and H0 is the Hubble constant.

2. How does Hubble's Law relate to the expansion of the universe?

Hubble's Law is evidence for the expansion of the universe. As galaxies move away from each other, the space between them is also expanding. This expansion is described by the Hubble constant, which is a measure of the rate at which the universe is expanding.

3. What is special relativity and how does it relate to Hubble's Law?

Special relativity is a theory proposed by Albert Einstein that describes how objects behave at high speeds. It states that as an object's velocity approaches the speed of light, its mass increases. This concept is relevant to Hubble's Law because as galaxies move away from each other at high speeds, their masses also increase.

4. Does the velocity of an object affect its mass?

According to special relativity, the velocity of an object does affect its mass. As an object's velocity increases, its mass also increases. However, this effect is only significant at speeds close to the speed of light, and is not noticeable in everyday objects.

5. How does the increase in mass due to velocity affect the understanding of Hubble's Law?

The increase in mass due to velocity has important implications for our understanding of Hubble's Law. It means that as galaxies move away from us at high speeds, their masses also increase, which affects the overall dynamics of the universe. This is an important factor to consider when studying the expansion of the universe and the behavior of galaxies.

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