Dark Matter: Is a Revolution Coming to Physics?

What is dark matter? Does it even exist, or do we just need an adjustment to our theory of gravity?

What is dark matter? It has never been observed, yet scientists estimate that it makes up 85% of the matter in the universe. The short answer is that no one knows what dark matter is. More than a century ago, Lord Kelvin offered it as an explanation for the velocity of stars in our own galaxy. Decades later, Swedish astronomer Knut Lundmark noted that the universe must contain much more matter than we can observe. Scientists since the 1960s and ’70s have been trying to figure out what this mysterious substance is, using ever-more complicated technology. However, a growing number of physicists suspect that the answer may be that there is no such thing as dark matter at all.

The Backstory

Scientists can observe far-away matter in a number of ways. Equipment such as the famous Hubble telescope measures visible light while other technology, such as radio telescopes, measures non-visible phenomena. Scientists often spend years gathering data and then proceed to analyze it to make the most sense of what they are seeing.

What became abundantly clear as more and more data came in was that galaxies were not behaving as expected. The stars at the outer edges of some galaxies were moving far too fast. Galaxies are held together by the force of gravity, which is strongest at the center where most of the mass is. Stars at the outer edges of disk galaxies were moving so fast that the force of gravity generated by the observable matter there wouldn’t have been able to keep them from flying out into deep space.

Scientists thought that there must be more matter present in these galaxies than we can currently observe. Something must be keeping the stars from flying away, and they called that something dark matter. They couldn’t really say what properties it might have except that it must have gravitational pull, and there must be quite a bit of it. In fact, the vast majority of the universe (a whopping 85%) must be dark matter. Otherwise, galaxies wouldn’t have been able to stick around as long as they seem to do. They would have broken up because there wouldn’t have been enough gravity to keep the trillions of stars in place.

When it comes to science, the trouble with something that you can’t observe is that it’s hard to say much about it. Because dark matter does not interact with the electromagnetic force — which is responsible for visible light, radio waves, and x-rays — all of our evidence is indirect. Scientists have been trying to figure out ways to observe dark matter and make predictions based on theories of it but without much success.

A Possible Solution

Newton’s Theory of Gravity explains most large-scale events fairly well. Everything from throwing the first pitch at a Yankees game to the movements of constellations can be explained using Newton’s theory. However, the theory is not foolproof. Einstein’s theories of general and special relativity, for example, explained data that Newton’s theory couldn’t. Scientists still use Newton’s theory because it works in the overwhelming majority of cases and has much simpler equations.

Dark matter was proposed as a way to reconcile Newtonian physics with the data. But what if, instead of reconciliation, a modified theory is needed. This is where an Israeli physicist named Mordehai Milgrom makes an entrance. He developed a theory of gravity (called Modified Newtonian Dynamics or “Mond” for short) in 1982 that postulates gravity functions differently when it becomes very weak, such as at the edge of disk galaxies.

His theory does not simply explain the behaviors of galaxies; it predicts them. The problem with theories is that they can explain just about anything. If you walk into a room and see that the lights are on, you can develop a theory that cosmic rays from the sun are hitting hidden mirrors in just the right way to light up the room. Another theory might be that someone flicked the light switch. One way to separate good theories from bad ones is to see which theory makes better predictions.

Recent analysis of Mond shows that it makes significantly better predictions than standard dark matter models. What that means is that, while dark matter can explain the behavior of galaxies quite well, it has little predictive power and is, at least on this front, an inferior theory.

Only more data and debate will be able to settle the score on dark matter and Mond. However, Mond coming to be accepted as the best explanation would shatter decades of scientific consensus and make one of the more mysterious features of the universe much more normal. A modified theory may not be as sexy as dark, unseen forces, but it may just have the advantage of being better science.

AstrophysicsDark MatterPopular
Comments ( 44 )
Add Comment
  • Buk

    “yet scientists estimate that it makes up 85% of the matter in the universe.”

    Should read:
    1) ‘yet scientists think that it makes up 85% of the matter in the universe.’
    2) ‘yet scientists guess that it makes up 85% of the matter in the universe.’
    3) ‘yet scientists invented the term and concept in a vain attempt to explain the discrepancies in their much vaunted, but inreconsilable, ‘the universe and everything’ assumptive calculations.

    Or, they don’t have a good explanation for stuff, so they invented a benevolent God to explain it.

    • Denver

      when did yo mama start letting you out unsupervised?

  • Yoram Har-Lev

    Hubble measured distances and speed between galaxies not between galaxies and the explosion as he should.Distant galaxy is also a galaxy nearer to the explosion (because of the time it take to the light to travell) and therefore get a stronger push from the explosion which account to hjgher speed.Galxies are not on the same distance from the explosion on the inflated universe.

    • TheHeck

      What explosion are you talking about? Big Bang? That wasn’t an explosion in the sense you are talking about. You should read up on the topic.

      • Mike Pollock

        No, you should think about the topic for once. Why wouldn’t you call the expansion of the universe from some point nobody can explain an explosion? Is it because you’re unable to admit something was here before that exploded? Do you have to make sure the universe was magically created? What caused your “expansion”? Magic? How did the “singularity”, or whatever you want to call it, overcome all the gravity it must have been creating to expand out at the speed of light? Don’t you ever think about Newton’s third law of motion? How did it all get so hot in the beginning? Just more magic from Father Lamaître? There needs to be reasons to explain all this, not just an acceptance that there are no answers.
        Of course, dark matter exists. Why do you think space is such a specific temperature of absolute zero? It takes matter to do that.
        You’re one of the countless people that think everything is all wrapped up with the Big Bang theory even though it ridicules every, single law in the book. The Big Bang was simply our universe turning itself into a particle collider by colliding two objects in an already existing, static universe. That is the the way the event that happened 13.8 billion years ago conforms with the laws.
        What you need to read up on is unsolved physics problems. There is a massive amount of them. What has happened over the last several decades is people have learned to not think about them because the Big Bang theory is a fact and nobody wants to be bothered with any problems. It is just staggering what a priest did to physics and astrophysics.

    • Dan

      Distant galaxies don’t get a stronger push in that sense because it’s not an explosion in the way we think of it. It is the creation/expansion of space itself. However galaxies should slow down because gravity should only pull on them from the “center” but they aren’t slowing down which is what is still unexplained.

  • Mark Richards

    I like this “Mond theory” a lot better than dark matter theory. Not only does Mond have predictive power, which is a requirement for something to be labeled a proper scientific theory, it doesn’t require “and then magic happens” (so to speak) to be hastily inserted in the spots where scientists simply don’t have all the facts. Dark matter and dark energy are a “God of the gaps” type of science argumentation and I was never comfortable with it. Of course, I’m not a scientist, so who knows.

    • TheHeck

      I agree. We postulated dark matter in order to explain gravitational anomalies, and we ‘detect’ dark matter using gravitational anomalies. It’s circular reasoning. MOND is a more elegant model, but there is definitely polishing required (esp when it comes to modeling galaxy clusters). Still, it’s way better than magic matter.

  • Joe Bakhos

    I’ve put forward a modified gravity hypothesis that explains galactic rotation rates and also cosmological expansion without the need of dark matter or dark energy.

    This hypothesis also includes an adaptation of general relativity that explains time dilation and energy increase at relativistic velocities and within a gravity well, while retaining Euclidean space.

    Part of this hypothesis includes the idea that higher concentrations of neutrinos may inhibit quantum processes. Please take a look at my paper and comment if you deem it appropriate.

    A copy may be downloaded here:


    • TheHeck

      You lost me at the second paragraph. Gravity behaves differently in other star systems? We have observed other star systems, with stellar and non-stellar companions. None of them do anything that Newtonian gravity doesn’t predict. And why would that matter when Oumuamua entered our solar system – the observed acceleration happened here, not in another solar system. The rest of the paper is an exercise in unfounded claims and “here magic happens.”

  • Ed Stauffer

    Liquid or gaseous dark matter would solve a lot of the biggest cosmology questions. An active galactic nucleus would function as a vaporizer resulting in the circulating dark matter having a circular Einstein ring. A quiescent black hole would result in an oval Einstein ring as there would be more liquid dark matter circulating along the plane of the galaxy as the gravity of the black hole would function as a condenser. The longer the galaxy has been in one state or the other the more distinct the difference should be

  • Dennis

    Sorry, no. This is a very disingenuous article.

    First, yes, MOND explains galactic rotation curves better than dark matter does. But that’s it.

    Dark matter explains the cosmic microwave background, large scale structure, galaxy clusters, gravitational lensing, the Bullet cluster and the cluster Abell 520, and also is consistent with a host of cosmological observations (e.g., nucleosynthesis, supernovae data, cluster estimates of the matter density) that MOND isn’t.

    All that remains is finding dark matter directly. Maybe we can, maybe we can’t (yet). How long till we verified the existence of the Higgs?

    (E. Siegel’s work referenced)

    • TheHeck

      CMB is interpreted to support lambda CDM. The main assumption is that the first peak indicates that the universe is flat. Or, more accurately, that the universe is “on average” flat. In that case the peaks in the power spectrum should indicate an additional, but unobervable gravitational component, and this has been attributed to dark matter.

      However, if the universe was “on average flat”, but had small localized gravitational “dips” or ripples, it would also result in the same power spectrum. Granted, MOND does not explain how localized anomalies could come in to being in a chaotic manner – but keep in mind that MOND postulates that the effects of gravity are modified by the acceleration. We have no high resolution acceleration data from the CMB to create the kind of map necessary to show whether MOND predictions pan out.

      Keep in mind – CMB shows gravitational irregularities. Dark matter is “observed” through gravitational irregularities, and was invoked to explain away the said irregularities. So we have to be very careful not to fall in to circular reasoning.

    • TheHeck

      When it comes to galactic clusters, the dark matter hypothesis doesn’t explain everything either. In fact, the two cases that you mentioned are the polar opposites of each other, right? In the bullet cluster collision the dark matter stays with the luminous matter and abandons the gas, and in Abell 520, it decides to stay in a “dark core” and let the luminous matter go flying away.

      A less convoluted explanation might be that there is a huge amount of not-yet-detected, concentrated conventional matter in galaxy clusters that take part unscathed in the “swarms of bees” type of collisions. These could be dim globular cluisters, free floating stellar mass black holes, orphan planets, ejected binary companions, etc.

  • Beau Jenks

    I know you are but what am I?

  • siempre

    Excellent article dealing with the changing consensus on gravity.
    That consensus is changing now because the senior scientists who developed the Dark Matter concept are retiring so actual data can get published that gives better findings.
    Science is political, oligharchal and run by money like all endeavors. When someone says ‘the Science ‘ you know they really mean..’the Politics ‘.

  • Tom McLernon

    So what about Dark Energy? What observation is it the answer to

    • TheHeck

      It was invoked to explain the fact that distant Type 1A supernovae are dimmer than we expect them to be. That means, the universe is accelerating. If there is 5 times more dark matter than observable matter, then a powerful repulsive force was required to explain the acceleration.

  • d

    try hydrinos!

    • TheHeck

      I’ll stick with Gatorade, thanks.

      • d

        Enjoy your Gatorade! Doesn’t change the fact that many scientists have reproduced his work and verified hydrinos exist! Explain where the significant energy production comes from if not hydrino formation!

  • Howard Jeffrey Bender, Ph.D.

    Another possibility, from a view of String Theory, is that Dark Matter appears to us as an effect of string/anti-string annihilations. As you may know, quantum mechanics requires that strings must be formed as pairs in the quantum foam – a string and an anti-string – that immediately annihilate each other. Quantum mechanics also requires both the string and anti-string to be surrounded by “jitters” that reduce their monstrous vibrating energies. What if this jitter remains for a fraction of an instant after their string/anti-string annihilations? This temporary jitter would be seen by us as matter, via E=mc2, for that instant before it too returns to the foam. That’s why we never see it – the “mass” lasts only for that instant but is repeated over and over and over, all over. Specifics on this can be found by searching YouTube for “Dark Matter – A String Theory Way”

    • TheHeck

      That would require the dark matter distribution to be on average homogenous. However, the gravitational anomalies that imply the need for dark matter are localized, eg. in galactic haloes. This is the point where you have to resort to magic.

  • Jared Irvan

    Ummm pretty sure 85% isn’t correct. 5% baryonic matter. 26% Dark matter the rest is Dark Energy. Dark matter and energy are not the same thing.

  • Paul Berning

    I’ve been hearing a lot about this Mond Theory and how it is supposedly better than dark matter theory in explaining orbital velocities in galaxies. What I have not heard mentioned is how well it explains gravitational lensing in galaxy clusters. The recent JWST images show plenty of that for example. It needs to compete with dark matter there as well.

  • Deano68

    This all assumes materialism and naturalism as the hidden assumption. Why not assume design and try to create predictive models that explain the facts we observe. Dark matter was a “god of the gaps” assumption that isn’t panning out, right so, for predictive analysis what would a design assumption uncover as explanatory power and predictive and testable outcomes. Ps forget any religious implication to this thought, but take a purely agnostic position and assume an engineer designed the laws at play.

    • TheHeck

      If we invoke a magical sky fairy everytime we see something we don’t (yet) understand, we’d still be huddling in caves marveling at Donner throwing thunderbolts around. I’ll stick with science, but you are free to go play the harp with your fairy.

  • Michael Scott

    You are including Dark energy in that estimate of 87 percent

  • Anonymous sanjay

    How could be ant body explains it.
    What is black energy observer.
    How can exposed.

    • TheHeck

      Ant body no dark, no? Can very exposed.


    Looks like Dark Matter is involved Black Holes

  • Hawk Winters

    Dark Matter is already being destroyed as a theory by advances in viewing technology. We are seeing ever more normal matter in all of the places that Dark Matter is predicted to be. It should have been scrapped as a theory a long time ago, but too many people (who call themselves scientists) have staked their entire reputation on a false paradigm.

  • Robert John Hebert

    The terms “Dark Matter” and “Dark Energy” were conceived of as a joke by scientists to fill a space where knowledge and wisdom was completely lacking… They are terms for nothing more than bad mathematics and are non-sensical values for where much more needs to be learned before scientific opinion and research can make any educated headway.

  • nick mcintyre

    Could be worse they could have “faith” dark matter exists like religious mythology does

  • Andy

    Dark matter is the black part of a negative electron. ELECTRON FLOOD THEORY. DURR

  • Harikrishnan

    The Nāsadīya Sūkta, also known as the Hymn of Creation, is the 129th hymn of the 10th mandala of the Rigveda. It is concerned with cosmology and the origin of the universe. It begins with the following statement.

    “There was neither death nor immortality then;
    No distinguishing sign of night nor of day;
    That One breathed, windless, by its own impulse;
    Other than that there was nothing beyond.

    Darkness there was at first, by darkness hidden;
    Without distinctive marks, this all was sea of darkness;
    That which, becoming, by the void was covered;
    That One by force of heat came into being;”

    Please note that the Vedas were written in 4500 BC when the rest of the world was in stone age. The Vedas also state that shape of the universe as Aandakataha ( egg shaped) and describes earth as Bhoogola ( round earth).

  • Clintox

    Or maybe having a theory that shows the true origin of gravity (which should include it’s relationship with other fundamental forces) could resolve these cosmological discrepancies. I would urge us to see an interesting paper, it’s link can be found at the end of this comment. In the paper, there seems to be more to gravity than what Newton and Einstein had shown us. Just in case the MOND model doesn’t do a satisfactory work at some point later, the perspectives of this paper could be handy, especially for those seeking a unified theory for all fundamental forces. This the link to the paper


  • Mark Bloomfield

    Are we just still riding the shock wave from Big Bang? Still Court in its vibration??

  • Bruce Fein

    Nicolai Levashov knows what dark matter is. Read his books.

  • Enbang Li

    As well known in the field, Vera Rubin discovered the flat rotation curves of spiral galaxies using optical spectra, which could be a Noble prize worth discovery. However, very few people noticed that when Vera Rubin interpreted her observational results, she made a very simple mistake: She applied the spherical model to the spiral galaxies (see the paper published in Science by Vera Rubin: Science, New Series, Vol. 220, No. 4604 (Jun. 24, 1983), pp. 1339-1344). Also, when you read the paper published by Fritz Zwicky in 1937 (THE ASTROPHYSICAL JOURNAL, Vol. 86, No. 3, 217-246) carefully, you will notice that he also utilized a spherical model to estimate the mass of the Coma cluster.
    As every physicist should know, an object with a spherical mass produces a Keplerian rotational curve, but a disk-like mass distribution will not follow that. Therefore, the key issue is how the mass is distributed in a galaxy. Any galaxy with a spherical (or close to spherical) mass distribution will not need dark matter. The results of NGC1052-DF2 and DF4 are the examples. The flat rotation curves of spiral galaxies are caused by the disk shaped (non spherical) mass distributions.
    With the latest GAIA data, we can show that by using a disk mass distribution model and by solving the Poisson equation of the Galaxy, we obtain a flat rotation curve which reproduces the key observed features with no need for a dark halo (https://arxiv.org/ftp/arxiv/papers/1612/1612.07781.pdf).
    By the way, MOND is just another way to reflect the effects caused by the non-spherical mass distributions. If MOND is correct, how can Newtonian mechanics work for DF2 and DF4 without modifications?
    Just a few days ago, the LZ released its first science results. As has happened many times before, “For now it’s kind of a weird thing, we’re saying that we’re the best in the world at finding nothing,” (https://www.newscientist.com/article/2327468-worlds-most-sensitive-dark-matter-detector-tested-for-the-first-time/).
    So, dark matter does not exist and it is just a consequence of misusing Newton’s law in gravitational systems with non-spherical mass distributions. Newtonian mechanics does not need to modify when the non-spherical mass distributions are taken into account.

    • luca

      A few comments:
      1) a disk with circular orbits without a DM halo is fiercly unstable, and destroies in a couple of rotations. No way to have a rotating stellar disk. This need of DM is surprisingly overlooked by several writers.
      2) DM in disk galaxies is NOT deduced by the rotation curve of stars. It is known since 50 yrs that an exponential disk (as real galaxies) produces a flat rotation curve in the visible part. DM is deduced from the rotation curve of HI well outside the end of the optical disk.
      3) DM is needed by several other diagnostics, not last gravitational lenses. And the predictions of GR, hydrostatic equilibria of hot gas, and stellar dynamics are in excellent agreement.

  • Noriaki Namba

    I pointed out the flaws in MOND theory in my paper* published in 2002.

    “Modified Newtonian dynamics (MOND) has recently been the focus of much attention/. MOND, developed by M. Milgrom, proposes a revision of Newton’s second law of motion in order to explain. Flat rotation curves of galaxies. Milgrom claims that because the second low of motion only applicable in cases of high acceleration-such as with the planets in the solar system-the law is not applicable in cases of extremely low acceleration-such as with stars in their galaxies.・・・
    However, MOND is designed only to explain flat rotation curves of galaxies and does not seem to have any other theoretical necessity. Thus why does Newton’s second law of motion need to be revised in cases of extremely low acceleration? Is there any reason other than to make the law match what has been observed? The cores of rich X-ray clusters of galaxies show a considerable mass discrepancy. Yet the MOND theory does not explain this well. Why? Because the acceleration of galaxy cores is not low. This phenomenon, however, can be explained without contradiction using inertial induction-the effect of inertial induction is strongly apparent due to the high density of the cores.”

    All the celestial bodies that make up the system are in free fall (acceleration) toward the center of the system.
    Gravity is the action that tries to maintain a defined acceleration towards the gravity source according to the distance from the gravity source.
    Therefore, if the gravity source accelerates, the gravitational action should be considered different from when the gravity source is stationary.
    Sciama named this action “inertial induction” and proposed it.
    All the stars that make up the galaxy are in free fall (acceleration) toward the center of the galaxy. Current calculation methods do not take this fact into account at all.
    There is no way that the observation can be explained by a calculation method that ignores the facts.
    I have written a paper* on how the inertial induction of stars works in galaxies.

    *N. Namba, “Stellar movement in the galaxy explained by inertial induction”, Phys. Essays 15, 156(2002)

    In addition, I mentioned the essence of gravity and inertia in a 2014 paper, showing that the existing theory of gravity is incomplete.
    The full text of this paper is now available on GALE ACADEMIC ONE FILE.
    Please see attached.



    … oh, a new explanation for dark matter. So great… But where is evidence, dude…