# Mass in the universe?

1. May 4, 2010

### cragar

Assuming that none of the energy in the universe was being converted into
mass and vice versa , could the mass in the universe be infinite , And this would not imply
creation of energy , I am just asking if it is possible to have an infinite amount of mass in the universe , I don’t know if this is the right place to post this.

2. May 4, 2010

### Kracatoan

Surely if there was infinate mass, you would have infinate curvature and everyone would get unhappy?

3. May 4, 2010

### cyberfish99

No, the law of conservation of mass says that matter can not be created or destroyed. The universe started with a certain mass, m, so while there is a finite amount of mass in the universe, it may just be hard for humans to measure it.

4. May 4, 2010

5. May 4, 2010

### cyberfish99

It is not possible. First, where would this infinite mass come from? Second, as far as all physicists and researchers know, the universe contains an finite amount. I have to eat my own words, scientists have determined the mass of the universe based on stellar density, about 8 times 10 to the 52 kilograms

6. May 4, 2010

### cragar

The same place the mass in the visible universe came from ,

7. May 4, 2010

### Nabeshin

This is garbage. There is no conservation of mass law, only a conservation of energy. Any particle accelerator or high atmospheric disturbance readily "produces" mass out of pure energy.

It is not possible to have an infinite amount of mass in a finite universe, for if this were so the universe would immediately collapse into a black hole and there would be no universe to speak of. If you're familiar with the anthropic principle, I am appealing to that here. You can always ask, "well why didn't the universe have 1kg more energy than it does?" and I highly doubt anyone will ever be able to answer such a question. From current, well establish physics these are simply initial conditions that were given to our universe. I refuse to delve into more skepticism than this.

8. May 4, 2010

9. May 5, 2010

### LionAndCobra

Do we really know that the universe does not have infinite volume? We think we know how old it is, and we think we know how big it is - but a key part of the history of science is the discovery of new information that reveals the errors of past ideas.

Personally, I doubt that the universe has infinite size and/or mass, but one man's beliefs on the matter (i.e. mine) mean very little, really. I find the Big Bang theory hard to accept, since it fails to answer a lot of questions - such as 'what triggered it?', 'what, if anything, existed beforehand?' and, more importantly: 'if the total mass of the universe (assuming it isn't infinite) was initially a point mass, how come the universe isn't itself just a grand black hole (but perhaps it is)?' - so while I like to keep track of what the astronomers and astrophysicists are saying, I also keep a large dose of skepticism handy for when people say they've a definitive answer for questions such as "could the mass in the universe be infinite?"

10. May 5, 2010

### cragar

ya and why is it always the big bang , and why not steady state theory or some other theories ,

11. May 5, 2010

### Nabeshin

That's why I limited myself to an infinite mass in a finite volume. Infinite mass in infinite volume is more complicated. What I posted is indeed a fact.
Here's something that's really important: Classical big bang theory does not attempt to describe up to the singularity or anything like that. All it says is that earlier in the history of the universe the universe was smaller and consequently more dense and consequently hotter. This has been pretty well established for a while now, and at this juncture there's hardly any point in trying to refute it. What happens when the universe becomes small in size is much more complicated and classical BBT does not attempt to explain. Other models have things to say here, but I'm not terribly up to date on those so perhaps someone else (marcus?) could give an overview of the state of affairs as far as they're concerned.

12. May 5, 2010

### Nabeshin

Like steady state theory, most (all?) alternate explanations do not fit all the data. The BBT survives because it fits basically all the data we have at the current time. This is ultimately why the BBT wins out.

13. May 5, 2010

### Stanwyck66

Maybe that is why is a theory and not a law? I'm sure no one here (or anywhere for that matter) is claiming to answer every question the universe gives us. We're always learning.

14. May 7, 2010

### Chronos

I'm not convinced any of our interpretations of physics can be claimed as "law", merely the best fit to observational evidence. BBT fits more observational evidence than any other conjecture. That is what science is all about.

Last edited: May 7, 2010
15. May 13, 2010

### hkyriazi

Regarding BBT, correct me if I'm wrong, people, but I was under the impression that cosmologists were still searching for direct evidence that distant galaxies are actually receding from us. (For example, by looking at apparent galaxy sizes over time.) In other words, they are trying to verify that the redshift-distance relationship really does result from an expanding universe.

16. May 14, 2010

### Chronos

The redshift - distance relationship [expansion] is well established. Acceleration is less well founded, but, pretty solid based on the perlmutter studies.

17. May 15, 2010

### hkyriazi

Chronos, I was under the impression that some folks still are (unsuccessfully) trying to come up with workable versions of "tired light" (a la Fritz Zwicky) to explain the redshift/distance relationship. Any expansion is purely inferential. Interestingly, one of your tagline quotes is from a fellow who wrote a book in 1909 titled "The Ether of Space" and another in 1925 titled "Ether and Reality". (Of course, he also penned something called "The Reality of a Spiritual World" in 1930, so...)

18. May 15, 2010

### SpaceTiger

Staff Emeritus
We do in fact study the redshift-distance relationship very carefully, but not to see if the universe is expanding. Rather, cosmology is now at the stage where we are attempting to measure the precise behavior of the expansion in more detail. The vast majority of astronomers treat both expansion and acceleration as a given, but we still don't know much about the "dark" components of the universe (dark energy, dark matter) that led to the behavior that we observe.

19. May 16, 2010

### cph

SPT has about 2000 clusters (and ACT 1000+) for SZ effect - redshift independent distance indicator, which is not consistent with an accelerating universe model.

20. May 16, 2010

### SpaceTiger

Staff Emeritus
Do you have a citation for this statement? The latest SPT results report *21* detected SZ clusters: