How the Universe Ends

[Speakpigeon]

Don't know how the universe ends, this thread seems to be infinitely expanding.

Q
Queue untermensche.

Cue?

Curlicue?

Curly Q?

Are straight queues even possible?

Just expanding a bit on the idea.
EB

 

[Cheerful Charlie]

Sighhhhhh. Again. The Universe is expanding. Really expanding, that is space is increasing at galactic scales. Because of that for an observer, there is a limit beyond which anything observable, like photons would have to travel faster than light to reach said observer. So nothing beyond a certain distance can ever be observed. We can have infinite stars but we can never see but a paltry sample of them. Not even in principle.

Is space expanding or is C changing? There is no way to know.

https://en.wikipedia.org/wiki/Expansion_of_the_universe

....
These situations are described by general relativity, which allows the separation between two distant objects to increase faster than the speed of light, although the definition of "separation" is different from that used in an inertial frame. This can be seen when observing distant galaxies more than the Hubble radius away from us (approximately 4.5 gigaparsecs or 14.7 billion light-years); these galaxies have a recession speed that is faster than the speed of light. Light that is emitted today from galaxies beyond the cosmological event horizon, about 5 gigaparsecs or 16 billion light-years, will never reach us, although we can still see the light that these galaxies emitted in the past. Because of the high rate of expansion, it is also possible for a distance between two objects to be greater than the value calculated by multiplying the speed of light by the age of the universe. These details are a frequent source of confusion among amateurs and even professional physicists.[3
...

Understanding why cosmologists think there is strong evidence for this is left as an exercise for the reader.

 

[Jokodo]

Sighhhhhh. Again. The Universe is expanding. Really expanding, that is space is increasing at galactic scales. Because of that for an observer, there is a limit beyond which anything observable, like photons would have to travel faster than light to reach said observer. So nothing beyond a certain distance can ever be observed. We can have infinite stars but we can never see but a paltry sample of them. Not even in principle.

That's the obvious conclusion. And one of the things that lead to it, excluding (at least) a static universe of which the visible universe is a fairly typical, or at least not entirely untypical, sample, is Olber's paradox.

- - - Updated - - -

Sighhhhhh. Again. The Universe is expanding. Really expanding, that is space is increasing at galactic scales. Because of that for an observer, there is a limit beyond which anything observable, like photons would have to travel faster than light to reach said observer. So nothing beyond a certain distance can ever be observed. We can have infinite stars but we can never see but a paltry sample of them. Not even in principle.

Is space expanding or is C changing? There is no way to know.

C changing wouldn't have the same observed effects.

 

[Loren Pechtel]

Sighhhhhh. Again. The Universe is expanding. Really expanding, that is space is increasing at galactic scales. Because of that for an observer, there is a limit beyond which anything observable, like photons would have to travel faster than light to reach said observer. So nothing beyond a certain distance can ever be observed. We can have infinite stars but we can never see but a paltry sample of them. Not even in principle.

Is space expanding or is C changing? There is no way to know.

C is changing.

(doesn't like ad blockers)
https://developerinsider.co/c-programming-language-version-history/

 

[bilby]

Sighhhhhh. Again. The Universe is expanding. Really expanding, that is space is increasing at galactic scales. Because of that for an observer, there is a limit beyond which anything observable, like photons would have to travel faster than light to reach said observer. So nothing beyond a certain distance can ever be observed. We can have infinite stars but we can never see but a paltry sample of them. Not even in principle.

Is space expanding or is C changing? There is no way to know.

C is changing.

(doesn't like ad blockers)
https://developerinsider.co/c-programming-language-version-history/

c, on the other hand, is constant BY DEFINITION.

Both c and the second are defined as constants; So the only one of the three fundamental units of measure used in the measurement of speed that can vary is length; The length of the metre is known only to the accuracy of our ability to measure. Getting a more accurate measure of the length of the metre is (confusingly) often referred to as 'measuring the speed of light', but the speed of light is exactly 299 792 458ms^-1, and the second is exactly 9 192 631 770 times the period of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. Only the metre can vary (although as its length is already quite accurately known, it can't vary by much).

One metre is by definition one 299 792 458th of the length of the path travelled by light in a vacuum in a second, so however long it is, c remains constant.

 

[steve_bank]

If everything changes in scale there is no way to detect it with SI fundamental units.

 

[steve_bank]

Sighhhhhh. Again. The Universe is expanding. Really expanding, that is space is increasing at galactic scales. Because of that for an observer, there is a limit beyond which anything observable, like photons would have to travel faster than light to reach said observer. So nothing beyond a certain distance can ever be observed. We can have infinite stars but we can never see but a paltry sample of them. Not even in principle.

Is space expanding or is C changing? There is no way to know.

https://en.wikipedia.org/wiki/Expansion_of_the_universe

....
These situations are described by general relativity, which allows the separation between two distant objects to increase faster than the speed of light, although the definition of "separation" is different from that used in an inertial frame. This can be seen when observing distant galaxies more than the Hubble radius away from us (approximately 4.5 gigaparsecs or 14.7 billion light-years); these galaxies have a recession speed that is faster than the speed of light. Light that is emitted today from galaxies beyond the cosmological event horizon, about 5 gigaparsecs or 16 billion light-years, will never reach us, although we can still see the light that these galaxies emitted in the past. Because of the high rate of expansion, it is also possible for a distance between two objects to be greater than the value calculated by multiplying the speed of light by the age of the universe. These details are a frequent source of confusion among amateurs and even professional physicists.[3
...

Understanding why cosmologists think there is strong evidence for this is left as an exercise for the reader.

That seems to be the gist of what I read. Space is not changing, space-time changes.

 

[Loren Pechtel]

C is changing.

(doesn't like ad blockers)
https://developerinsider.co/c-programming-language-version-history/

c, on the other hand, is constant BY DEFINITION.

Both c and the second are defined as constants; So the only one of the three fundamental units of measure used in the measurement of speed that can vary is length; The length of the metre is known only to the accuracy of our ability to measure. Getting a more accurate measure of the length of the metre is (confusingly) often referred to as 'measuring the speed of light', but the speed of light is exactly 299 792 458ms^-1, and the second is exactly 9 192 631 770 times the period of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. Only the metre can vary (although as its length is already quite accurately known, it can't vary by much).

One metre is by definition one 299 792 458th of the length of the path travelled by light in a vacuum in a second, so however long it is, c remains constant.

Note that what I was quoting used an uppercase C.

 

[bilby]

C is changing.

(doesn't like ad blockers)
https://developerinsider.co/c-programming-language-version-history/

c, on the other hand, is constant BY DEFINITION.

Both c and the second are defined as constants; So the only one of the three fundamental units of measure used in the measurement of speed that can vary is length; The length of the metre is known only to the accuracy of our ability to measure. Getting a more accurate measure of the length of the metre is (confusingly) often referred to as 'measuring the speed of light', but the speed of light is exactly 299 792 458ms^-1, and the second is exactly 9 192 631 770 times the period of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. Only the metre can vary (although as its length is already quite accurately known, it can't vary by much).

One metre is by definition one 299 792 458th of the length of the path travelled by light in a vacuum in a second, so however long it is, c remains constant.

Note that what I was quoting used an uppercase C.

Note that I said 'on the other hand', signifying that I had already noted that.

 

[steve_bank]

C is defined in a vacuum. It will be slower in a medium it travels through. Propagation of signals in a cable or on a circuit baord will be less than C in accordance with the dielectric constant of the material.

Send an RF pulse through a block of teflon and it slow down then speed back up when it exits the block. Relative to an observer outside the block.