2

While reading a recent Creation Ministries article Five atheist miracles, I came across this claim:

Here is the first problem: how do you get gases formed in a rapidly expanding primordial universe to coalesce together to form a critical mass so that there is sufficient gravitational attraction to attract more gas to grow a star? Gases don’t tend to come together; they disperse, especially where there is a huge amount of energy (heat). Hey presto! Cosmologists invented ‘dark matter’, which is invisible undetectable ‘stuff’ that just happens to generate a lot of gravitational attraction just where it is needed. More magic!

The author in question seems to be awfully sure of his position. I thought that cosmologist indirectly observed the effects of dark matter and that is why it exists.

Did the hypothesis of dark matter arise to explain how stars formed in the primordial universe?

  • 1
    Reminder: Comments are for improving the question, not pseudo-answers nor sharing your opinions on the outgroup. – Oddthinking Apr 22 '16 at 6:36
14

The following lists just some of the evidence for dark matter.

  1. Dark matter was first proposed by Fritz Zwicky in 1933, when he discovered that galaxy clusters do not have enough visible mass to hold them together. The galaxies move so fast that, if there were no invisible matter, they would leave the cluster and we would not be able to observe any such clustering.

  2. The rotational speed of stars around a galaxy should drop off as you get further from the centre. Instead it tends to stay almost constant. This implies that there is invisible mass away from the galactic centre. This was first reported by Vera Rubin in 1975.

  3. Gravitational lensing also shows clearly that clusters are surrounded by a halo of invisible matter. It was first proposed by Einstein (who thought it would probably never be observed) ands is now a technique that is routinely used to observe extremely distant galaxies.

  4. Observations of the Cosmic Microwave Background show that there is a lot of matter that does not interact with electromagnetic radiation. As dark matter is only affected by gravity (and possibly the weak force) this has the right characteristics to account for this.

  5. In the last decade or so, when computers became powerful enough, modelling of the early universe gives the correct, observed results only if dark matter is included in the simulation.

All these (and many more) reasons are why scientists are convinced dark matter exists. And no, dark matter was not invented to explain the coalesced gases in the primordial universe. That was just a recent additional fact that added yet more proof to our belief that dark matter is out there.

Science does not rely on supernatural beings or magic - unless, of course, you believe in The Magic of Reality.

All this and a lot more evidence for the existence of dark matter can be found on Wikipedia.

| improve this answer | |
  • This is probably the best answer as it makes the key point with respect to the original question - it wasn't cosmologists coming up with Dark Matter to solve early universe questions. Dark Matter was originally proposed as a solution to a known problem with the rotation curve of galaxies. It was only much later that it was used in cosmology. – KAI Apr 22 '16 at 14:31
  • Basically, dark matter was not invented, it was discovered. To be specific the words "dark matter" was invented (what we normally call "coined") in order to give this phenomenon a name so that we can do research to figure out what it is. The first step in a discovery is to name a thing so we can talk about it. – slebetman Apr 25 '16 at 3:50
  • 2
    Technically dark matter was invented. We needed some way to explain our observations of stellar motion around galactic disks, and dark matter happened to comport with several other otherwise unexplained phenomena. Discovering it requires observing it directly, which we haven't found a way of doing yet, and why we still call it "dark". – J Doe Feb 28 '17 at 23:25
7

Dark matter is hypothetical -- no one knows if it actually exists or what it is. What has been seen are various gravitational effects on matter, such as stars, or energy, such as cosmic microwave background.

It is not claimed that it is undetectable, but directly undetected. This is so because little is known beyond its gravitational interaction, but the most common currently claimed origin of dark matter are WIMPs which do interact with other forces.

An undetectable matter would not affect the universe and would certainly not be adopted by physics -- it is not falsifiable. Also, it would explain nothing.

Dark matter is a hypothetical substance that is thought by most astronomers to account for approximately 85% of the matter in the universe. Although it has not been directly observed, its existence and properties are inferred from its various gravitational effects such as the motions of visible matter, via gravitational lensing, its influence on the universe's large-scale structure, and its effects in the cosmic microwave background.

[...]

Although the existence of dark matter is generally accepted by most of the astronomical community, a minority of astronomers argue for various modifications of the standard laws of general relativity, such as MOND, TeVeS, and Conformal gravity that attempt to account for the observations without invoking additional matter.

Many experiments to detect proposed dark matter particles through non-gravitational means are under way.

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

| improve this answer | |
2

"Dark matter", in the sense of unobserved matter causing gravitational effects, was first considered in the 1922 article First Attempt at a Theory of the Arrangement and Motion of the Sidereal System Astrophysical Journal, vol. 55, pages 302-328, by Jacobus Kapteyn.

Kapteyn does discuss kinetic gas theory in this article, but in the sense that each star would be considered a single gas particle.

The portion of the article that is about dark matter is on page 314:

Remark. Dark Matter. It is important to note that what has been determined is the total mass within a definite volume, divided by the number of luminous stars. I will call this mass the average effective mass of the stars. ...

Now suppose in a volume of space containing l luminous stars there be dark matter with an aggregate mass Kl average luminous stars...

So Kapteyn conceived of dark matter just out of completeness, admitting that there could be unobserved matter that cannot be accounted for by observing light from stars.

Only later did others propose that significant amounts of dark matter existed, based upon otherwise insufficient gravity to hold galaxy clusters together and to cause the observed rotation speeds of stars about the center of their galaxy.

| improve this answer | |

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .