When looking at the theories for Dark matter from afar, it seems kind of humorous in a way when none of our instruments can detect it yet.(Current picture of Dark matter as shown on a black background) Sorry could not resist... Scientists are not 100% certain it exists. Dark matter is one of the few theories that is being used to explain the problem of unaccounted for mass in observed galaxies. Kindly note that mass is not weight in the way we describe it here on Earth. Mass is the quantity of matter an objects consists of. Weight is the effect gravity has on it. Since, by nature, dark matter is not detectable with conventional technology due to it's inability to emit radiation or light It is essentially invisible. To see Dark "Stuff" astronomers look at the behavior of objects near the dark matter.One of the first to recognize something just wasn't adding up was Fritz Zwicky a Bulgarian born Swiss but worked in America astrophysicist. His "observations" of dark matter were done while studying the motions of faraway galaxies in 1933. Zwicky estimated the mass of the observed galaxies by measuring their brightness. He then used a different computation method to determine the mass. Hold the Phone! The result was 400 times larger than his initial method. Oddly enough Zwicky's research results were a lot like Dark matter. They were unnoticed until the 70's of the 20th century - losing decades of potential research in this field. Scie
ntists realized that Zwicky's observations could explain some of their own. Today , dark matter is being taken seriously.Some astronomers believe that over 20% of our universe is made up of what we call "dark matter", and another 67% of dark energy. Oh and the stuff we are familiar with and can actually look at only takes up 10% of the universe. Our universe is dominated by dark matter and dark energy, whatever they may be. The number might even be closer to 95% for Dark matter/energy.
Recently (2006) British researchers from the University of Cambridge made some interesting discoveries. Their calculations show that dark matter particles are moving at an amazing speed of 9 kilometers per second, a lot faster than previously thought. The researchers have also been able to determine the temperature of this particular dark matter, 10,000 °C.
Enough of all that... what is dark energy/ mass? The club seems to be getting crowded with MACHOs (MAssive Compact Halo Objects) and WIMPS ( Weakly Interacting Massive Particles) and Nonbaryonic particles This is mass but not Electrons Protons or Neutrons. Other candidates include Neutrinos and the evil twin,Massive
Neutrinos, Axions, and supersymetric particles like Neutralinos . I do have to say that MACHOs have pretty much been voted out of the club since they do not come in large enough numbers to be a player but I love the acronym so I included it.WIMPS are making a case for the lead so far. Image Credit: Sky & Telescope / Gregg DindermanRight Now we are all over the map but Scientists have come to some conclusions. Dark Matter is most likely Nonbaryonic in nature, so generally the dark matter debate falls into one of three camps ( I will get to the alternate theories in a few ) Hot Dark Matter, Warm Dark Matter and oh yes, Cold Dark Matter. Each one right now has some of the questions answered but not all of them. Every day we are learning something more about the world we live in. I will lightly touch on alternate theories, well some of them.
The biggest line of reason to scrap the whole dark matter thing lies in our possibly incomplete understanding of gravity. Several system are being proposed but all have problems that cannot be answered yet.The MOdified Newtonian Dynamics (MOND) is one such theory. That theory has trouble reconciling the gravitational lensing events as Light is bent around galaxies from further out sources. Other systems trying to answer the problem of who hid the mass in the universe include The Tensor-Vector-Scalar which answers a bunch of the question of early models. Quantum mechanics has a candidate in there too and there is the Dark fluid answer. So far nothing is certain except we do not know yet. I suspect we will in the mid future. I look forward to that day when one team takes the prize and gets the Nike endorsements! All of the others start working on the next big thing... Until then ...
Clear skies and great seeing too
Steve T
We all need to step back from the brink and recall Occam's razor. Why are so many otherwise extremely intelligent people chasing after something that has nearly proven itself not to exist already? Let's refocus our energies where they belong: Understanding gravity correctly and completely. Dark matter is like the ether, an imaginary construct created to resolve a consflict so that scientists didn't have to alter preconceptions.
ReplyDeleteIf the dark matter comprises 25% of the stuff of the universe, you would think it be easier to detect. After all it been searched for by teams of scientist using multimillion dollar detectors for over 16 years. It could be that we have been hoodwinked by an artifact for the last 300 years in the same way that the Scholastics were hoodwinked for 1000 years by an artifact due the earth rotating on its axis every 24 hours. That artifact gave the false impression that all the objects in the Heavens rotated around the earth in 24 hour period.
ReplyDeleteThe artifact that we may have been misled by is due to the close association between mass and luminosity. It is altogether possible that it is the luminosity that is doing the gravitational attraction and not the mass. In other words, it could be the sun's warmth and not its mass that is attracting the planets. This possibility can be easily determined with experimental equipment that costs around $100. Go to http://vixra.org/abs/0907.0018 and there you will find 5 experiments which show that when heat transfers through a test mass its weight will either increase of decrease depending on whether the heat flows up or down through the test mass. The percentage change in weight of these test masses ranges from 2 % to 16%. It time to start thinking about the dark matter and dark energy problem and stop spending close to billion dollars clinging to the Standard Model. Being hoodwinked by an artifact for 300 years is better that being hoodwinked for a 1000 years.
@Cinci Tim: "Why are so many otherwise extremely intelligent people chasing after something that has nearly proven itself not to exist already?"
ReplyDeleteWhere did you get the idea from that Dark Matter has nearly proven itself not to exist?!? It's quite the other way round: there are *lots* of pieces of evidence that it exists.
"Dark matter is like the ether, an imaginary construct created to resolve a consflict so that scientists didn't have to alter preconceptions."
And probably you would have said something similar between 1843 and 1846, the time it took from John Adams' prediction of the existence of Neptune until its discovery; and between 1933 and 1956, the time it took from Pauli's suggestion that the neutrino exists until its discovery...
@Peter Fred: "If the dark matter comprises 25% of the stuff of the universe, you would think it be easier to detect." That's a non sequitur. First, although in the mean there is much more dark matter than baryonic matter in the universe, its density still is very small. Second, the dark matter particles probably are only very weakly interacting, even less than neutrinos. And look how long it took to detect neutrinos after they were first postulated!
ReplyDeleteBjoern said, "And look how long it took to detect neutrinos after they were first postulated."
ReplyDeleteThe results of my experiments experiments could represent a "serious anomaly" that may be up there with the serious anomaly produced by photoelectric effect experiment or Rutherford's gold foil experiment.
They suggest that it is the heat of the sun and not its mass that attracts the planets or it is the heat of the earth and not its mass that attracts the moon.
Then we should do what Newton begged future generation to do: We should try to find out what is this mysterious, yet-to-be-specified property of mass that gives it the ability to either attract mass or warp space? But this is like asking those unthinkingly accepted Aristotelian astronomy: What is this mysterious, yet-to-be-specified property of the earth that gives it the ability to make all the objects in the Heavens rotate around it in a 24 hour period?
@Peter Freud: I'm not interested in discussing the results of your experiments; I only addressed your claim that "If the dark matter comprises 25% of the stuff of the universe, you would think it be easier to detect." Why did you chose to ignore my arguments?
ReplyDeleteYou think I am the one that is ignorant because I do not pay much attention to your argument that the reason why dark matter cannot be detected is because of its low density. Respected scientists were looking for the ether as late as 1925. The search for the ether was finally halted by the acceptance of a new theory that revolutionized our way of thinking about nature. I want you to examine my experimental results because they hint in order to get rid of our need for dark matter we may need we my need to undergo a radical change on how gravity works. Almost to a one to days scientist hold the view that some mysterious, yet-to-be specified property of mass can either attract mass or warp space. This fanatical belief in the mysterious attractive power of mass and the unseen dark matter is bolstered by artifact that gives the impression that mass mediates the gravitational force. My experiments provide credence and insight into the nature of this artifact. The Aristotelians were pretty smart but they were misled for a 1000 years by an artifact that gave false impression that the Heavens rotated around the earth every 24 hours. My experiments show that we have only been led for 300 years by an artifact that has duped us into the belief that mass can attract mass.
ReplyDelete@Peter Fred: Nice that you at least noticed my first argument - but you nevertheless still ignore the second...
ReplyDeleteWith respect to your claims that we don't need dark matter, because your "experiments provide credence and insight into the nature of this artifact" - well, you have a good chance to convince me: Simply explain the observations of the Bullet Cluster (quantitatively, not only with some vague just-so stories!), since that is one of the best pieces of evidence we have for the existence of dark matter. If you don't know what the Bullet Cluster is - here is a nice paper on it: http://arxiv.org/abs/astro-ph/0608407