The invisible matter might be a better name for it. It cannot be seen or detected by any instrument. We only know it’s there because of its gravitational effects on regular matter and light.
In 1933 Swiss astronomer Fritz Zwicky, working at Caltech, was studying the Coma Cluster of galaxies. The Coma Cluster, about 320 million light-years away from us contains over 1,000 galaxies. It is the nearest cluster to our home cluster, the Virgo Cluster, which contains our home galaxy, the Milky Way.
Galaxies in a cluster are held together by gravity and rotate around the center of the cluster. They don’t all rotate in the same direction but rather all rotate in different directions. Zwicky noticed something strange about their rotational speed. They were all rotating way too fast. That is the amount of visible matter in the cluster was not nearly enough to hold the galaxies inside the cluster, they should have long ago escaped the cluster. Zwicky calculated that the cluster needed 400 times as much matter as was apparent from observation to hold the cluster together. (Since Zwicky’s time that number has been reduced but the cluster still rotates far too fast for the assumed matter present.) Zwicky assumed that there had to be far more matter in the cluster than could be observed. He called this matter “dark matter”.
But Zwicky was kind of an eccentric and no one paid much attention to him. So there the matter rested until 1965 when American astronomer Vera Rubin, studying the Andromeda Galaxy while working at the Carnegie Institute, noticed something very strange about the rotational speed of the stars in the outer reaches of the galaxy. They were rotating far too fast. At the speed they were traveling they should escape the galaxy and travel forever into intergalactic space. There was just not enough matter to hold them in orbit at the speeds they were traveling. At the speeds they were traveling, there needed to be from five to six times as much matter as could be observed in stars and the calculated matter in intragalactic dust clouds and atomic particles such as hydrogen.
This chart, credit Quorm.com, shows how dark matter in a galaxy affects the rotational speed of stars.
But the evidence for dark matter does not stop there. Galaxies and galactic clusters form a gravitational lens that bends the light around them. The light from galaxies and clusters behind them is bent into an arch.
The top Hubble Telescope image is gravitational lensing around a single elliptical galaxy and the bottom is a Hubble Telescope image of gravitational lensing around a galactic cluster. I would estimate that the ring of light is at the very edge of the dark matter cloud. Hundreds of such images can be found here: NASA images of gravitational lensing
Astronomers calculated that there was not nearly enough matter in the galaxy or cluster to have such a dramatic effect on light from the distant cluster directly behind the galaxy or cluster. They calculated the amount of light bending would require about six times the gravitational force that would normally come from the stars they could see and the intergalactic dust and particles that would normally be there.
The above graph, credit Emagill.com, gives the percentage of dark matter and dark energy as well as regular atoms in the universe
But is Dark Matter Necessary?
Most, but not all, cosmologists agree on this. Yes, they say, dark matter is necessary, not just for the formation of galaxies but for the formation of rocky planets around secondary stars. This article in Forbes explains why. This is the best article I have found on dark matter and is a must-read for anyone interested in the subject.
The Universe Would Be Very Different without Dark Matter
They argue that dark matter must exist for a variety of reasons. Here is just one of them. The author argues that without dark matter there would be no life anywhere in the universe. This is a fantastic article that everyone interested in the subject should read. The below paragraph explains what a solar system would be like without dark matter.
“On smaller cosmic scales, that means that the only solar systems that exist will be enormously simplistic. Without the ability to recycle the elements from one generation of stars into the next, that means that you won’t have the heavy elements needed to form rocky planets in your protoplanetary disks. Without large abundances of carbon, nitrogen, oxygen, and even heavier elements like silicon, phosphorous, copper, and iron, not only would life be an impossibility, but the only planets you could form would be gaseous worlds composed of hydrogen and helium.”
Yes, galaxies would likely form without dark matter. But such galaxies would have no rocky planets, therefore, no life. We would not exist if there were no such thing as dark matter.
However dark matter is something very strange. Not only does it have no charge, but it also has no electrical or magnetic properties whatsoever. The only thing it has in common with regular matter is gravity. Dark matter has the same gradational effects as regular matter, there is just from five to six times more dark matter than regular matter. In addition to having an attractive force, or gravitational force, dark matter must also have a repulsive force.
That is, dark matter cannot be allowed to mix with regular matter. If it could, then it would behave just like regular matter. If it could then stars would be 84% dark matter and would not shine. There would be no stars or planets. So, it must have a gravitational effect on regular matter, but if it gets too close, close enough to mix, it must repel regular matter. It cannot clump together with regular matter. Dark matter particles, if it is a particle, must have a gravitational effect on other dark matter particles, but must repel other dark matter particles at microscopic distances. It must never clump together.
If dark matter could clump together like regular matter, there would be dark matter stars, but they would not shine, and there would also be dark matter black holes. In other words, if it could clump with itself, it would behave just like regular matter. Most of it would be in the center of the galaxy and thin out with the distance from the center, just like regular matter does. Dark matter must exist only as a cloud, never as clumps.
I hear some YouTube speculators say things like, “thousands of dark matter particles are passing through your body right now. I think that is nonsense. They seem to believe dark matter particles behave like neutrinos. Dark matter must be cold or slow. That is, it does not travel, like neutrinos, at near the speed of light. It is just there, moving slowly around the galaxy as it rotates.
This is Arvin Ash’s estimate of the distribution of dark matter around a galaxy. The galactic disk is in the center. This is a flat spiral galaxy. An elliptical galaxy would have a different profile of course. This is only a theoretical estimate but it must be pretty close as to how dark matter is distributed.
But what does all this mean?
We know that the many constants of nature are fine-tuned. We know that all the particles and the forces of nature are fine-tuned. And now we find there is something called dark matter that is the epitome of fine-tuning.
The universe’s particles, constants, forces, and laws fit together like a jigsaw puzzle. Every one of them, including dark matter, must fit together in time and in space to bring about the universe as we know it. The more we find out about the universe, the more we realize just how incredibly fine-tuned it is.
And yet there are still those who still think it was all an accident. So biased is their dogmatic world view that nothing, absolutely nothing can be allowed that even hints of some kind on conscious mind having anything to do with it.
I am a biblical atheist. I do not believe in the God of the Bible or the God of any other religion. I fully realize that all so-called revealed religion is bullshit. This has nothing to do with religion. I hope my lifelong animosity toward religion has not robbed me of the ability to reason, or of my ability to use simple common sense.
Hey people, think about it, it’s a no-brainer!
I will have a new post about every ten days or so. If you would like to be notified of every new post then email me at DarwinianOne@gmail.com
Thought you might be interested in this article on the Big Think “Ask Ethan: Why can’t black holes be made of dark matter?” — I’m assuming your spam filter will stop me posting the URL in full — bigthink dot com/starts-with-a-bang/black-holes-dark-matter/ and anyway, Google will find it. In summary, rather than containing a repulsive force, dark matter doesn’t interact enough with anything to lose enough momentum to clump together sufficiently tightly. But it could have, if there was sufficient density of dark matter to begin with. But there was no where near enough.
Thanks Pete, I will check it out. I don’t think my spam filter will reject URLs.
I really don’t think black holes could be made of dark mater. Dark matter seems to not allow itself to clump together like regurlar matter. If it did then it would behave just like regurlar matter. Dark matter particles, if they exist, seems to have some characteristic that does not allow them to get too close together, that is not to clump.
By now, the dark matteris is the modern equivalent of the epicycles of Ptolemy. The ”dark matter” has never been detected despite decades of research with more and more costly detectors.
And what can we infer from this? That dark matter does not exist? Or perhaps it is because their detectors are inadequate. They, the scientists, assume that dark matter can pass through the earth and through the walls of the container containing the chemical that will interact with dark matter. Perhaps dark matter avoids any very close contact with regular matter, therefore, cannot reach the detector fluid. I would expect this would be the case, that it is that dark matter repels close contact with regular matter, else it would just mix with regular matter.
A good primer on the existence of dark matter, thanks.
I’ll check out that article.
Rusty, that was not the reply I was hoping for. The essay was not intended to be a primer on the evidence for dark matter. What I was hoping for was your thoughts on my conclusion. That is this line: “Hey people, think about it, it’s a no-brainer!”
Would it be asking too much for your opinion on that line? And be brutally honest. You will definitely not hurt my feelings.😂
Well first, I’m not sure what yet another example of fine tuning adds to the discussion.
In fact, I find the argument that dark matter is another example of fine tuning a bit circular. We have no idea what exactly dark matter is or where to find it. We assigned it certain properties, some of them, such as a repellant force (anti-gravity), quite unusual. How did we determine the properties of dark matter? By working backwards to determine what exactly those properties HAD to be in order to fill in the gaps between what we can see/measure and what we can’t. To then say, “see, the properties we assigned to dark matter (because we had no other way to make our observations align with our calculations) are another example of fine tuning” seems a bit of a reach.
And I have to disagree with your statement “So biased is their dogmatic world view that nothing, absolutely nothing can be allowed that even hints of some kind on conscious mind having anything to do with it.” While I do find it an interesting thought experiment, my mind can no easier comprehend the idea of a extra-universal creator than it can an infinite multiverse. To simplify, I guess, I can’t comprehend anything extra-universal. And our species’ historical attempts to explain away things they do not understand as the work of some god, has nothing to do with that inability. To refer to the existence of something beyond our own universe as a “no-brainer” seems to smack, to me, as biased or dogmatic.
Just my thoughts.
Rusty, I have put your comments in italics in order to distinguish them from mine.
Well first, I’m not sure what yet another example of fine tuning adds to the discussion.
It adds everything to the discussion. If I give you evidence that John stole your car because I showed you a video of him driving it around, that is one bit of evidence. Then if I showed you a video of him actually stealing it, that is another example that adds to the evidence. If more evidence does not add to the conclusion, then I have no idea what evidence is.
In fact, I find the argument that dark matter is another example of fine tuning a bit circular. We have no idea what exactly dark matter is or where to find it.
Nonsense, we know exactly where to find it. We find it in the halo of galaxies, and we find it in the intergalactic matter within galactic clusters.
We assigned it certain properties, some of them, such as a repellant force (anti-gravity), quite unusual. How did we determine the properties of dark matter?
By observing how it behaves. We observe it exist primarily in the halo of galaxies, not in the center like ordinary matter. We observe that it doesn’t clump into dark matter stars or planets but exist as a cloud only.
By working backwards to determine what exactly those properties HAD to be in order to fill in the gaps between what we can see/measure and what we can’t.
No, that is not how we determined the properties of dark matter at all. We simply observed the way it behaved. That is all. End of story.
To then say, “see, the properties we assigned to dark matter (because we had no other way to make our observations align with our calculations) are another example of fine tuning” seems a bit of a reach.
For starters, we did not assign anything to dark matter. To observe how something behaves and to then to say that if something behaves in such a matter, it must have these qualities, is not to assign them anything. It is simply to observe the qualities it possesses.
And I have to disagree with your statement “So biased is their dogmatic world view that nothing, absolutely nothing can be allowed that even hints of some kind on conscious mind having anything to do with it.” While I do find it an interesting thought experiment, my mind can no easier comprehend the idea of a extra-universal creator than it can an infinite multiverse.
I thought I had already dealt the death blow the multiverse explanation. Surely one can understand that picking one number from infinity is a long shot. But then if you must pick two numbers from infinity without even once picking a wrong number. Not a chance. But it does not stop there. You must pick at least 50 numbers, FROM INFINITY, and every one of them must be correct. And in every drawing, from infinity, you must never pick a wrong number. If that does not deal the death blow to the multiverse theory then nothing does.
To simplify, I guess, I can’t comprehend anything extra-universal.
Of course you can’t. That’s my whole goddamn argument. You cannot comprehend it. Your worldview does not permit you to comprehend it. Therefore you must, you must, you must deny it.
And our species’ historical attempts to explain away things they do not understand as the work of some god, has nothing to do with that inability.
Well “historically” that is indeed the case. But no longer. Now a certain segment of the population explains the unexplainable as simply a brute fact. That is they do not attempt to explain it at all. They just say as Sean Carroll implies in his book, “The Big Picture”, “The fiscal laws of the universe proves that the non-physical does not exist.” Dogmatic circular reasoning if it ever existed.
To refer to the existence of something beyond our own universe as a “no-brainer” seems to smack, to me, as biased or dogmatic.
I made my case in several posts. Not one point I made was refuted. The multiverse was and is the only option cosmologists offer as a refutation to my argument. They say, not me mind you, but they say the multiverse is the answer to the fine-tuning argument. I have destroyed that argument in spades! No one has even attempted to refute it. NO ONE! Goddammit, I have a right to say it is a no-brainer until someone even attempts to refute my argument.
I rest my case.
OK. Should I remind you again that this is a thought experiment? You cannot prove that you are right or that others are wrong. To insist that your argument is unrefuted is…pointless?
In 1937, Amelia Earhart and her navigator were reported missing. It’s my contention that they were beamed aboard an alien spaceship and whisked away to another planetary system. No one has yet refuted my argument. NO ONE!
Perspective and objectivity.
Everyone who disagrees with you is not biased and dogmatic. And to insist such is pointlessly argumentative and alienating.
No, it is not a thought experiment any more than the Big Bang is a thought experiment, or dark matter is a thought experiment. These are genuine scientific conclusions that science has arrived at by observation. And my argument has definitely not been refuted, it is legitimate. But now I do understand your argument. We will discuss that later. But please watch this 12-minute video interview with physicist Leonard Mlodinow. Mlodinow is one of the giants in cosmology. He understands what is meant by fine-tuning and of course, he opts for the multiverse as does about 90% of all cosmologists. My point is HE UNDERSTANDS the argument. It is clear from your argument, that it is just a thought experiment, which means you do not understand. The video: https://www.youtube.com/watch?v=oaVlTIymQ3g
But thanks for your reply. It is really an eye-opener for me. I now understand that even though almost every cosmologist agrees that the universe is fine-tuned because they understand the argument and almost every atheist who is not a cosmologist insists that it is not fine-tuned because they do not understand the argument.
“And yet there are still those who still think it was all an accident”
The cosmic entity that allegedly created the fine tuned universe had to come from somewhere.
If it came from a “non fine” tuned universe/medium/whatever….Then was it an accident?
I would also suggest, that if a cosmic entity evolved (as I have previously read Ron mention) then that is naturalisitc. Just outside of our universe.
“It’s turtles all the way down” – Stephen Hawking
From a non-fine-tuned universe? No, it would take fine-tuning to create any type of universe. And if it was created by a cosmic entity, or cosmic mind, or god-like thing or whatever you wish to call it, that would not be naturalistic. Perhaps supernaturalistic. 🤣
I have heard your quote many times before but that is the first I have heard it attributed to Stephen Hawking.
Hawking talks about it in “Brief History of Time”. After extensive GOOGLE research I agree…it wasn’t Hawking who originated it.
The quote, supposidly, comes from some cosmologist who when told: “The universe sits on an elephatant who sits on top of a turtle. He then asked “But what does the turtle sit on?” When some lady popped up and said: “Don’t be silly, it’s turtles all the way down.” However this is just a story that was told. The orgin of the quote is lost to antiquity. It probably never happened. Someone just made it up.
Fascinating!
Thanks Ron