A billion new stars make dark matter unnecessary?
Recent news says that astronomers underestimated the number of stars in the universe. With the additional billion stars, do we still need "dark matter" (which may not even exist) to explain the Big Bang theory?
- arslanLv 71 decade agoFavorite Answer
There are en estimated 300 billion stars in the milky way.
A few billion more is an insignificant number, a pin drop compared to the total number of stars.
And besides, Dark matter has nothing to do with the number of stars, it has to do with the behavior of galaxies. It is noted that galaxies are spinning to fast. And stars in the outer regions are moving very fast, when they should be moving slower. This is why astronomer came up with dark matter. A few million more stars wont affect the fact the Dar matter and Dark Energy both exist.
- RaymondLv 71 decade ago
The problem is not with the Big Bang theory, so it does not need the new stars.
The problem is with the behavior of galaxies themselves (much smaller scale problem than the whole Big Bang theory). Individual galaxies are spinning too fast -- at least, in terms of the matter we can identify.
In reality, the galaxies spin at whatever rate the laws of physics require them to rotate. When we take the observed rate of spin, we can calculated the amount of mass needed to keep the galaxy together despite the centrifugal effect of that spin.
The answer we find (for each galaxy) is big -- much more than the mass that we can directly see through the normal matter. That is why the "dark matter" was imagined. What is the nature of the mass that is needed to keep the galaxies together? We know it cannot be stars (otherwise, we'd see them -- remember: this problem involves all galaxies, including those that are close to us).
In addition, there was an additional problem that at large distances, even more matter was "missing". The "extra-missing" stuff might be what was found recently. However, this does not help the original dark matter problem.
The Big Bang theory simply explains what happens to a universe that expands, and where the energy content becomes less dense (the "temperature decreases") as the expansion goes on.
The theory can just as well explain the behavior of a universe with lots of matter as that of a universe with very little matter.
Because of the behavior of the universe as observed some time ago (it always takes time to analyze data), we were expecting the energy density to be at a certain level. We were expecting matter to be at a certain density to make the ratio "critical" (a value we call Omega and that we hoped was equal to "1").
What we found is that the "ordinary matter" density is far less than 1. Worst: the "dark matter" density does not make up the difference. The universe is still mostly energy (the energy we presently call "dark energy" because we do not yet understand it -- dark = unknown in this context).
Still, despite that, the matter we could actually detect was still a lot less than what the model told us. The newly detected stars may answer the problem of the missing "normal matter". The identification of the "dark matter" is a separate problem. And I won't even go into the dark energy problem...
- Anonymous1 decade ago
------- x 100 = 10^-11 or .00000000001%
That would be the percentage increase in the known mass of the universe due to the discovery of a billion new stars. That is, of course, an insignifcant number. But we don't even know the number of stars in the Milky Way to an accuracy of plus or minus one billion. In fact, the estimates I've seen vary by about 100 billion.
In any case, dark matter is needed to explain the evolution of stars and galaxies, not the big bang. The chances that dark matter doesn't exist are extremely remote.
- Tom SLv 71 decade ago
First, the Big Bang theory was around long before the idea of Dark Matter, so it does not require it. Dark Matter is thought to make up about 80% of the mass of the universe, a billion stars is a fraction of a single large galaxy.
Dark Matter would have more to do with the universe's ultimate fate, less so the beginning.
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- jean-de-la-luneLv 51 decade ago
1/ a billion star is a drop in the ocean
2/ by a slightly involved argument linked to the making of light nuclei in the early universe (as opposed to stars and stars explosions where all the rest is made) you can show that what is actually missing is 'nonbaryonic dark matter' that is, it cannot be made of the same stuff as the matter we know, it is, by necessity, some kind of heavy neutrino or supersymmetric particle. So finding more stars will not solve the problem. It could solve the problems of the rotation curves and clusters binding alluded to by Raymond, but not this one.
- Matt ELv 41 decade ago
given the prior measurement of "known" matter only made up 4-5% of the required energy/mass, I would say yes, dark matter/energy is still a factor.
The milky way alone is 300 billion-ish stars, Andromeda is estimated to be over 1 trillion. So a few billion more stars is merely a drop in the bucket.
Excellent question though.
- 1 decade ago
as the light from most of the stars will not arriuve on the earth in the next 100years why do we worry . The might have all imploded yesterday and before we know it we will have all been dead for agesSource(s): common sense