how big is universe ?

https://www.space.com/24073-how-big-is-the-universe.html

about the size of a cell.

we just live in it 😉

@beowulf said
about the size of a cell.

we just live in it 😉

Well, you know, there is something to that.

We could measure the diameter of the universe to an arbitrary degree of accuracy, and still in the end we would need to ask ourselves whether our universe is "big" or "small" -- there is no basis of comparison except ourselves, but we are part of the universe itself.

@ogb said
https://www.space.com/24073-how-big-is-the-universe.html

Nobody knows.
That is the concise answer.

Redshift is not only caused by a galaxy moving away from our galaxy, it could also be caused by the movement of our galaxy away from that other distant galaxy. Redshift alone could not possibly result in an accurate measurement of distance. The measurement of both galaxies movement relative to one another is needed to accurately measure distance using redshift.

All galaxies move relative to one another.

@metal-brain said
Redshift is not only caused by a galaxy moving away from our galaxy, it could also be caused by the movement of our galaxy away from that other distant galaxy.

Wow - how could you miss the point of relativity so very badly!?

@shallow-blue said
Wow - how could you miss the point of relativity so very badly!?

WOW. How could you make up something so irrelevant and expect people to think you know what you are talking about?

@metal-brain said
WOW. How could you make up something so irrelevant and expect people to think you know what you are talking about?

He's right, you're wrong. End of.

@suzianne said
He's right, you're wrong. End of.

None of you can explain why I am wrong but you are the last word. Right.
Tell us again why you think time dilation is the result of gravity.
Simply tell us all why gravity would cause time dilation.
We are all waiting.

@Metal-Brain
The amount of redshift is one indicator, the other is cephid variables which are the standard 'candle' so if you measure the light from such a star, it will have a certain intensity as read out by instruments.
So they can tell by the strength of the light signal reaching Earth how far away that star is and if that star is in a distant galaxy we can suss out the distance of the whole galaxy and when you have several independent ways of measuring astronomical distance and they agree it is not a stretch for astronomers to agree the measurements are accurate within some window. We don't have to get a distance accurate to within a cm, from a billion LY out in space if we say it is 950 to 1100 mega light years away that is good enough.
Since you appear to have a Phd in astronomy, tell us just how it is done.

@sonhouse said
@Metal-Brain
The amount of redshift is one indicator, the other is cephid variables which are the standard 'candle' so if you measure the light from such a star, it will have a certain intensity as read out by instruments.
So they can tell by the strength of the light signal reaching Earth how far away that star is and if that star is in a distant galaxy we can suss out th ...[text shortened]... away that is good enough.
Since you appear to have a Phd in astronomy, tell us just how it is done.

"if you measure the light from such a star, it will have a certain intensity as read out by instruments. "

A lower light intensity could be because it is a smaller star rather than a more distant star. How would you determine which it is without sacrificing accuracy?

@Metal-Brain
You do that by spectrographic analysis, there are lines in the spectrogram showing what elements are present in that star, lots of iron, meaning it is older or iron poor meaning it is either young or not able to crunch fusion much to produce star poop, which is iron, the end point of fusion.
So the amount of iron is one indicator of the mass, that and the basic color, is it clocking in mostly red, showing it to be maybe a star that already went nova and that is the result or is it mostly blue saying a much more active fusion going on inside, where our sun kicks out a lot of yellow showing the midrange of mass.
So why are you asking us amateurs here, instead of just posting that question on google? Is it because you just want to show your incredible intelligence and therefore much higher on that scale than us low class clowns?

@metal-brain said
None of you can explain why I am wrong but you are the last word. Right.
Tell us again why you think time dilation is the result of gravity.
Simply tell us all why gravity would cause time dilation.
We are all waiting.

You’re wrong because there is no difference between us moving away from an object and an object moving away from us

@Metal-Brain
We could tell you time 'dilation' is result of gravity, which is the result of mass effecting the curvature of spacetime and you are quibbling, there are TWO separate effects giving time 'dilation' and that is the greater the mass the slower time flows AND the greater the velocity of mass, the faster time flows compared to Earth time, if you go fast enough, you might reach a star in a week on YOUR clocks but if it was a thousand light years away, you are effectively going into your future because for you maybe a week goes by coming and going, because you are within a hair's breath of c but a thousand ly out, a thousand ly back, 2000 Years goes by on Earth, so you would have left everything you knew way in the past and you would be welcomed maybe, by strangers formerly 2000 years into your own future and you might only be 2 weeks older than when you left far back in time.
Having two separate effects giving 'time dilation' means there is something more fundamental going on that has to explain two separate but related phenomena.]
But that won't phase you since you only listen to your scientist of the month club.

@suzianne said
He's right, you're wrong. End of.

Suzianne does not like us, that’s all there is to it. Could it be our race?

@athousandyoung said
You’re wrong because there is no difference between us moving away from an object and an object moving away from us

Thumb up from AJoe.
Pure logic. Libs, even Thousand, don’t know logic from the cause of gravity.