# Calculating mass of the universe

sonhouse
Science 30 Sep '17 19:44
1. sonhouse
Fast and Curious
30 Sep '17 19:445 edits
Schwartzchild radius formula is 2GM/c^2. For the sun, about 3 Km. For Earth, about 8 mm. For Luna, about 100 Microns. G at about 6.67E-11 and M in Kilograms, c in meters/sec. (299792458 meters/second, squared is about 8.98E16 so 2*6.67E-11/c^2 is about 1.48E-27 which I call X. And Sr itself would be in meters.

The Schwartzchild radius of the universe is said to be 13.7 billlion light years.

So, making the 2G/c^2 part a new constant: ~1.48 e-27, calling that X. Then the Sr is now just X*M. So solving for M is now just Sr/X

Sr of universe at 13.7 E 9 ly in terms of meters is about 8.42E27 meters.

So M=8.42E27/1.48E-27 which is ~5.7 E54 Kg. Simple, eh.

So it seems to me if you could somehow be in the center of a black hole the mass of the sun and live, the visible edge of your universe would only be 3 Km away.
2. 01 Oct '17 06:11
Originally posted by @sonhouse
So it seems to me if you could somehow be in the center of a black hole the mass of the sun and live, the visible edge of your universe would only be 3 Km away.
Does measurements of length have any sense inside a black hole, because the spatial dimensions are so curled up?
3. 01 Oct '17 10:20
Originally posted by @sonhouse
Schwartzchild radius formula is 2GM/c^2. For the sun, about 3 Km. For Earth, about 8 mm. For Luna, about 100 Microns. G at about 6.67E-11 and M in Kilograms, c in meters/sec. (299792458 meters/second, squared is about 8.98E16 so 2*6.67E-11/c^2 is about 1.48E-27 which I call X. And Sr itself would be in meters.

The Schwartzchild radius of the universe ...[text shortened]... k hole the mass of the sun and live, the visible edge of your universe would only be 3 Km away.
Sorry, but I don't think so. How can one accurately calculate the mass of something they know so little about?
4. 01 Oct '17 10:411 edit
Originally posted by @mchill
How can one accurately calculate the mass of something they know so little about?
How do you know how much 'they' knows about it?

And it isn't the amount of info that counts as whether you can calculate it but rather the relevance of whatever you know to that calculation. For example, I don't have to know the first thing about the bird life on Earth to estimate its mass.
5. 01 Oct '17 11:042 edits
Originally posted by @humy
How do you know how much 'they' knows about it?

And it isn't the amount of info that counts as whether you can calculate it but rather the relevance of whatever you know to that calculation. For example, I don't have to know the first thing about the bird life on Earth to estimate its mass.
An Interesting thought, but since we know of such a tiny part of the universe, there are simply too many variables upon which to base an accurate measurement. In addition, our universe may be contained within a number of much larger universes, which are part of a multi dimensional system. How could we possibly calculate the mass of all that, with what we know now?
6. 01 Oct '17 12:2411 edits
Originally posted by @mchill
...since we know of such a tiny part of the universe, there are simply too many variables upon which to base an accurate measurement.
...
Please list some of these "variables" so to show how there are "too many" for an estimate and explain how so...
And what is wrong with an "estimate" rather than an "accurate measurement"? An estimate can be good.
our universe may be contained within a number of much larger universes,

Err no. Or at least as far as I am aware no such theory has ever been given any real scientific credence.

The default position should be if a theory has no evidence then, generally and depending on the assumptiveness of the theory, until if or when it has evidence, we should assume it to be extremely unlikely.
To see why that MUST be so, just consider the infinite number of alternative theories that also have no supporting evidence and which contradict that theory, such as our universe being within a supernatural rabbit that isn't itself a 'universe' because it has no spacetime because it is 'supernatural' etc, and then if you assign each one equal probability which you surely must as there is no more evidence to support one than the other (because there is NO evidence) , you will have to assign an infinitesimally small probability to each including your proposed theory.
7. 01 Oct '17 13:02
When we talk about our universe, we're just talking about our universe, not the whole unknown multiverse. Only our universe.

I'd say that the total mass of *our* universe is calculable.
8. sonhouse
Fast and Curious
01 Oct '17 14:271 edit
Originally posted by @fabianfnas
When we talk about our universe, we're just talking about our universe, not the whole unknown multiverse. Only our universe.

I'd say that the total mass of *our* universe is calculable.
Here is a professional astronomer, Phd, what he said:
"What is the mass of the Universe? (Intermediate)
What is the mass of the Universe? Also how can you prove that this is the true mass of the Universe?

As nobody knows the size of the universe, one cannot really talk about the mass of the universe, though one can talk about the mass of the observable universe. What is normally sought after is the density of matter in the universe (which is the mass per unit volume). This is what is important in determining the fate of the universe: whether it will collapse one day or whether it will continue expanding forever.

The density of matter in the universe can be measured by various means, which are too technical to go into at this point: people measure the density by studying the fluctuations in the Cosmic Microwave Background, superclusters, Big Bang nucleosynthesis, etc.

According to these studies, the density of matter in the universe is about 3 x 10-30 g/cm3, which means that it is 300 billion billion billion times less dense than water. Note that this includes the contribution of dark matter and so the density of luminous matter (that we see as stars and galaxies) is only about one-tenth of the figure given above.

Now, the size of the observable universe is about 14 billion light years, and using the above value of density gives you a mass (dark and luminous matter) of about 3 x 1055 g, which is roughly 25 billion galaxies the size of the Milky Way."

3 E55 grams and I got 5 E54 Kg. Not so far off, eh.

And of course that is just the observable universe. And I think he didn't take into account dark matter, not sure though.
9. vivify
rain
01 Oct '17 17:10
Originally posted by @sonhouse
Schwartzchild radius formula is 2GM/c^2. For the sun, about 3 Km. For Earth, about 8 mm. For Luna, about 100 Microns. G at about 6.67E-11 and M in Kilograms, c in meters/sec. (299792458 meters/second, squared is about 8.98E16 so 2*6.67E-11/c^2 is about 1.48E-27 which I call X. And Sr itself would be in meters.

The Schwartzchild radius of the universe ...[text shortened]... k hole the mass of the sun and live, the visible edge of your universe would only be 3 Km away.
If the universe has a mass, does that mean it has it's own gravitational pull?

*If* so, is there a way to calculate how strong the gravity of the universe is?
10. 01 Oct '17 17:16
Do we know where the universe ends?
11. sonhouse
Fast and Curious
01 Oct '17 17:243 edits
Originally posted by @vivify
If the universe has a mass, does that mean it has it's own gravitational pull?

*If* so, is there a way to calculate how strong the gravity of the universe is?
Well qualitatingly it roughly, it is clearly not enough to attract itself back to itself at least not yet since the entire universe has been and is stil expanding faster than the speed of light and it seems perhaps the speed of expansion sped up 5 billion years ago which lately there are theories that cast that into doubt.

What is not in doubt is the universe is still expanding faster that c so that says at least qualitatingly gravity is not strong enough to start the universe clumping back to a big crunch at least not in our epic of time.

Maybe a trillion years from now it might be different. One thing for sure, as the universe expands there is less and less we will see locally, in a billion years or so Andromeda and the Milky way will crunch into each other causing a burst of new star growth and such and they will settle down a billion years or so after that into a nice elliptical galaxy and then billions of years later all the other stuff will be flying away and we will see less and less and after a trillion years or so our galaxy will be the only thing seen in the entire visible universe leaving us in our epic knowing more about the universe in general than a civilization arising on some star a trillion years from now who may develop as technologically advanced as us (not that that is so huge in itself, but our present level)

At that time this far far future up and coming civilization will have telescopes at least as good as Hubble or James Webb and such maybe even better, say a 100 meter scope on an airless moon.

Even with that, there will be nothing for them to see no matter how hard they look because there will be nothing visible as the universe will have expanded to such a degree that the only thing in the observable horizon would be the home galaxy.

That's it for them so they will have a very truncated understanding of the universe compared to us who can at least see nearly 14 billion light years and have the advantage of seeing galaxies in all states of development.

Their red shift which will be very minor in their case since there will be nothing outside their home galaxy to reference any kind of doppler shift of light since there will be no light from distance sources to doppler at all. So we in fact ARE in a fairly special time in the universe to understand how it all got here, those folks from a trillion years from now will have no clue, only unprovable theories.

But back to the calculation of the mass of the observable universe, the fact the equation of the Shwartzchild radius and my method of just algebraicaly solving for M and coming so close to the Phd's estimate from a different direction says to me the idea that the observable universe IS the Schwarzchild radius of the universe which is like saying maybe a universe grows inside most black holes, a black hole in our universe becoming a white hole generating a daughter universe.

Maybe it takes a certain mass of a black hole to make a real universe if indeed that theory has any street cred at all, say a star of Sol's mass making a black hole a few km across would not be able to make a real universe just some kind of non-developing pile of gamma rays or something at the 'white hole' end of it.

Just me waving my hands to try to make sense of it allðŸ™‚
12. 01 Oct '17 21:041 edit
Originally posted by @humy
Please list some of these "variables" so to show how there are "too many" for an estimate and explain how so...
And what is wrong with an "estimate" rather than an "accurate measurement"? An estimate can be good.
our universe may be contained within a number of much larger universes,

Err no. Or at least as far as I am aware no such theory ha ...[text shortened]... will have to assign an infinitesimally small probability to each including your proposed theory.
Please list some of these "variables" so to show how there are "too many" for an estimate and explain how so...
And what is wrong with an "estimate" rather than an "accurate measurement"? An estimate can be good.

A. A few variables to consider are:
1. No known boundaries: This will make mathematical equations nearly useless
2. Black holes: Calculating the mass of a large number of vacuums with no known size is impossible without conventional points of reference.
3. Dimensions: If the universe is made up of a number of dimensions, as many scholars believe, how would you calculate the mass of dimensions we have no knowledge of?

B. What's wrong with an estimation? Nothing at all, but if your estimation is off by a massive amount, what use is it?

I admire your desire to undertake this task, but without more specific knowledge, I still don't see how it can be done.
13. 01 Oct '17 22:114 edits
Originally posted by @mchill
Please list some of these "variables" so to show how there are "too many" for an estimate and explain how so...
And what is wrong with an "estimate" rather than an "accurate measurement"? An estimate can be good.

A. A few variables to consider are:
1. No known boundaries: This will make mathematical equations nearly useless
2. Black holes: Calculatin ...[text shortened]... undertake this task, but without more specific knowledge, I still don't see how it can be done.
1. No known boundaries:

So just estimate the mass of the observable universe; problem solved.
Black holes: Calculating the mass of a large number of vacuums with no known size is impossible without conventional points of reference.

You are talking gibberish. Mass is something that may or may not be contained within a given volume and not an attribute of volume itself. The mass of a black hole is in its singularity. The mass of black holes can be and often has been reasonably estimated from its various observable gravitational effects, no problem.
3. Dimensions: If the universe is made up of a number of dimensions, as many scholars believe, how would you calculate the mass of dimensions we have no knowledge of?

You are talking gibberish. Mass is within the observable universe and we can make reasonable estimates of it.
but if your estimation is off by a massive amount, ...

their estimate is unlikely to be off by a 'massive' amount.
14. 01 Oct '17 23:30
Originally posted by @humy
1. No known boundaries:

So just estimate the mass of the observable universe; problem solved.
Black holes: Calculating the mass of a large number of vacuums with no known size is impossible without conventional points of reference.

You are talking gibberish. Mass is something that may or may not be contained within ...[text shortened]... massive amount, ...[/quote]
their estimate is unlikely to be off by a 'massive' amount.
So you have a problem with calculating the volume of entire universe?
15. 02 Oct '17 04:26
Originally posted by @eladar
So you have a problem with calculating the volume of entire universe?
And you don't?