An interesting piece in Universe Today over the weekend takes the dark matter out of the hunt for dark matter, but you're probably going to want to approach this one carefully--or as Universe Today says, "put on your skeptical goggles and set them to maximum." An Italian mathematician has done some creative number crunching and accounted for the force that holds galaxies together without the need for dark matter. It's a bold claim to make--and one that's going to get a good going-over from physicists.
A quick dark matter primer, for those who might be rusty: basically, if one is to simply tally up the amount of mass in spiral galaxies like our own and then model their rotation, we get a very different picture than the one we can empirically observe. The amount of mass at the center of spiral galaxies is huge, but outer stars move around the galactic disks so quickly that they should--according to the numbers--fly off into interstellar space. In fact, the visible objects at the Milky Way's center only contain about 10-20 percent of the mass needed to explain the rotation curves of the outer stars--and to keep the galaxy from coming unglued around the edges.
So, by deductive reasoning, modern physics has concluded that the rest of the mass holding galaxies together is invisible--it's dark matter. This is the stuff of Nobel prizes and very expensive orbiting scientific experiments. And now this guy Carati is mucking up the works with his numbers.
But the thing is, his math fits the models almost perfectly. Carati essentially says that--somewhat implausibly--the rotation curves can be explained by the influence of faraway matter on galaxies. It sounds pretty nonsensical--intuition says any gravitational influence exerted from outside the galaxy should help to pull the galaxy apart, not hold it together.
But apparently his math fits really well with what we can observe of galactic rotation (note: we've personally taken exactly zero steps to check Carati's math ourselves, but this is what we're told). It's an extraordinarily close fit actually, and he's shown that it works for at least four known galaxies. Which has led Steve Nerlich at Universe Today to outline the following four possible conclusions (and we're quoting here):
• There are so many galaxies out there that it's not hard to find four galaxies that fit the math;
• The math has been retro-fitted to match already observed data;
• The math just doesn't work; or
While the author's interpretation of the data may be up for discussion, the math really does work.
Like Nerlich, we're dialing up our skeptical goggles to "ludicrous skepticism." The idea that much of what we understand about physics is being explained away with some clever yet seemingly counterintuitive calculations doesn't seem likely. But it's an interesting notion nonetheless, and sometimes big science happens this way. More about Carati's math over at Universe Today, and the paper is at arXiv.
In short: We don't like the guy's claim so it must be wrong.
THIS IS LUDICROUS!!
First everyone tries to avoid the mathematical 'Invention' of dark matter in order to balance their equations. Now they act as if the existence of Dark Matter is firmly established and that they know its properties and how it affects things?!!!! Even though they full well know they haven't and are never going to find one single trace of it!!!!
I adore brain storming and thinking outside the box.
Yes, this will be met with skepticism; and that is to be expected.
I really appreciate this mathematician for making a fresh perspective of the masses and gravity
Universes and what is holding them together.
YEA! COOL! WONDERFUL!
I am not saying is correct. I have not a clue.
I appreciate his new perspective, well done!
Science sees no further than what it can sense.
Religion sees beyond the senses.
Let me ask a couple of questions, because I am not a physicist, but I want to understand what I am reading here.
So on theory is you have dark matter, which acounts for 80-90% of the mass to generate the gravity to hold the galaxy together while it rotates.
The other theory is that there is forces affecting the galaxy from the outside which holds it together.
Am I understanding these both? But these are both theories, right? So, how does the black hole in the center of the galaxy fit in?
@Cybegor don’t want to get shot for saying this. But there might not be a black hole in the center of our galaxy. (I think that it’s there) But in reality, black holes have never been observed…EVER. They are a mathematical construct from Einstein’s special relativity. He even said that they may not exist. But today we have them in the center of all galaxies. Black Holes, Higgs Boson, Dark Matter, are all theoretical constructs made up to explain away formulas that don’t balance. In reality, maybe none exist. I personally don’t believe in the Higgs Boson.
But I’d say your paraphrasing is correct. 1 theory is that there is mysterious “invisible” matter that accounts for 90% of matter in the universe. And the other is saying there is no such matter, that the galaxies are being held together by external forces, i.e other galaxies acting upon each other (like a house of cards).
I'm confused. I thought it was generally agreed that a "super massive" black hole is at the center of our galaxy and is holding it together. ??? But i suppose that could be considered black matter... oh well.
This is science at work ladies and gentlemen. Critique is an occupational hazard (albeit it doesn't justify the arrogance we so commonly find in modern scientists). I applaud this individual for having the balls to "swim against the tide" for the pursuit of truth. Algebraic equations are used ALL THE TIME to support/denounce theories, and it will be very interesting to hear how the scientific community approaches this.
A great scientist is a rare breed. Critical, but open minded. Creative, but reasonable. Intelligent, but wise. Your lucky if you see one in your lifetime.
Dark matter is a name title they give to invisible matter responsible for bonding the outter edges of a spiral galaxy. There's no correlation with quantum singularities (i.e. black holes).
Telescopes have observed the singular effects of black holes on other stars that they orbit around. Black holes are real, even supermassive ones. It's just currently theory that supermassive black holes reside in the center of spiral galaxies. Black holes are one end result to the death cycle of a star (other than white dwarf, neutron star, pulsar, etc.) It's the result of the mass of a star that has burned its fuel almost completely out, collapsing to a specified size designated by an equation called the Schwartzchild radius (which is used to calculate the distance from the center of a given mass at which the volume of the mass must be shrunk in order for the escape velocity to equal the speed of light; anything smaller and not even light would escape the gravitational effects of the concentrated mass). At that point they just suck any surrounding matter into it. Some spew jets of gamma rays from their poles; another means by how black holes are optically observed.
Supermassive black holes in the galaxy's center is suppose to be the massive gravitational force that keeps the stellar matter of the galaxy attracted and in a uniform rotation. The effects of the gravitational force should dwindle with distance towards the outer bands, but in fact is faster (uniform in appearance but faster in that outer rim stars have to travel at greater speeds to maintain the uniform rotation).
The theory part comes into play to explain why stars at the edge of the galaxy don't just fly off as opposed to staying bounded to the galaxy as they do.
But yes. They're both theories.
@pheonix1012 Thanks for the clarification. :)
I wonder if anyone has considered the time difference between light from the far side of the galaxy and the near side changing the shape of the visible galaxy, and thus the measured speeds. probably, but I've never heard anyone talk about it.
I haven't seen the math, and I doubt I could understand it, but I think I understand what he is getting at with external gravitational forces holding galaxies together. If you think of a gravity well as a sphere, each galaxy has a gravity well of monsterous size. At some point, there are places where galactic gravwells will intersect and overlap, much like the circles in a Venn Diagram. In these intersection areas, that is where you will find spiral galaxies. You would probably need an intersection point of 3 or more galactic grav wells, but then you can have networks of spiral galaxies, all interdependent on eachother's gravity fields to keep them from flying apart.
The black hole at the center of our galaxy cannot be directly seen, however it interacts with stars we can see. Based on the motion of stars that inhabit the heart of our galaxy, scientists can precisely calculate the mass and position of our galaxy’s black hole. It plays with stars like a juggler plays with bowling pins. Clearly there is SOMETHING there, call it what you will.
However, when scientist watched the movement of the stars at the outer edge of galaxies, they saw the stars were moving too fast. When they add all of the known mass of the central black hole, plus a very generous estimate of the mass of all the stars, dust, planets etc. they only have about 20% of the mass necessary to keep those stars in the outskirts of the galaxy from flying off into intergalactic space. So they named this mysterious 80% remainder dark matter.
I am impressed when observations confirm your theory AFTER your theory has been published (special relativity). Coming up with math that fits existing data is not as impressive. The question is: does Carati’s equations predict anything new that can be confirmed with new observations?
It's math, either it equates or it doesn't.
"But in reality, black holes have never been observed" well. I have to say you are wrong on this.
that is like saying there is no dead cat in the box until you open the box and observe it.
yes it impossible to SEE a black hole as it suck in light! but we have OBSERVED the phycial effects it has on surrounding matter.
what you are saying is like saying we have not observed the center of the earth. only proved it to exist because of math... that is hogwash!
there is more to science and observation than "math" and "VISIBLE observations"
can you see a light bulb when the light is on? no you can see the light coming from it. but you know there is a light bulb producing the light. The same goes for black holes. we can SEE the massive gas ejections from black holes and have pictures of the x-ray and gamma rays being shot from a black hole.
Technically speaking, a 'Black Hole' is a scientific construct to explain a myriad of unseen factors that produce a cumulative effect we can observe. Though in reality it is not one 'natural' "entity" Its just a grouping of factors that produce a observed result.
PS there isn't really any 'light' coming from a 'black hole' so can we immediately deduce there must be a black hole(so generically named) object with x properties that causes this and that? The Observed facts can be caused by any myriad of disconnected factors that produce the observed result. For all we know there are forces acting in unison that we can never grasp from such great distance.
Lets first sort out all the basics we have here observably near us! Then...nnn go to the basics of the basics.
Is gravity the only attractive force between celestial bodies?
Is it possible to have an electrostatic force too? Are all celestial bodies electrically neutral or are they charged? If they are charged, then there will be electrostatic forces between them.
The equations for the force of gravity and the force from electric charge are very similar:
F = G*m1*m2/r^2
F = ke*q1*q2/r^2
What kind of test will show if celestial bodies are charged or not? How much would they need to be charged to have the same attractive effect as dark matter?
"The Observed facts can be caused by any myriad of disconnected factors that produce the observed result."
Is this not true for EVERYTHING? And perhaps flies are spontaneously generated by rotting meat. It fits the observed results.
Isn't this the point of Scientific Theory? To explain which "disconnected factors" are likely causing the observed result?
I’m not saying they don’t exist, I’m just saying we are observing effects and calling it a “black hole” when it could be any number of other phenomenon. Google “Black Holes Don’t exist”….and you will get many papers from PHD physicists that will tell you what you are observing is not a “black hole”
Einstein himself did not believe in them, they were just a product of his formulas.
We know that the objects in our solar system are relatively neutral as far as a net electrostatic field. Other stars are really too far away to make accurate measurements. A electric field powerful enough to influence a star’s trajectory 4x more than gravity on a galactic scale would be easily detectable here on earth (and would be quite disruptive).
And if our galaxy’s outer stars did have an electro static charge large enough to be influenced by this galaxy wide field, they would exert a force on one another. Like charges repulse and opposite charge attract. This would be apparent in their trajectories.
"The Observed facts can be caused by any myriad of disconnected factors that produce the observed result."
Ockham's razor applies here. Why do we need to evoke "forces acting in unison that we can never grasp" for a phenomenon that is perfectly explained by established science?
Relativity predicted time dilation, gravitational lensing, frame dragging, etc. Relativity also predicts black holes. Gravitational fields bend light. A gravitational field strong enough will bend light back to its source. Why all the doubt and controversy?
That being said, what exactly occurs inside a black hole is up for debate. The Theory of Relativity breaks down at this point. This is where M-theory attempts to take over, however there is no real way to test M-theory at this point. So while the internal workings of a black hole are a mystery, their external influences are well understood.
Einstein himself doubted that matter would continue to compress into infinite density/energy/ (a singularity). He believed that a yet undiscovered force would come into play.
its fun reading scientific explanations on how our galaxy holds itself together, i feel like in 100 years or so we (as a race) will look back and laugh at our current scientific understanding of the universe. dark matter, higgs boson, alternate universes. we will consider those obsolete like ether or alchemy of past generations. (or be correct)
Maybe this is kind of like Einstein with the Unified Field theory. It too was scoffed and heavily criticized (as was Einstein for supporting it), but look at it now! Maybe this is another theory that is simply "before its time", so to speak.
Or it could be completely wrong on the other hand haha.
This article reminded me of that circumstance, though.
Dare to say the world is not flat! “OH MY anti-GOD!" say it aren’t so!
The article says his numbers make his argument or theory plausible. I appreciate a fresh new view with good science. Now it just needs to be supported from another source or 2.
For Galileo to say the world was round was being anti-godly during his time frame, if you get my drift now...
'Well Established' and 'Reality' are two different things...
Thanks for answering about electric charges and fields. I was expecting things within the solar system to be mostly neutral.
Maybe the heliosphere of the solar system is charged. Like a Faraday cage, the voltage can't be measured from the inside. Similarly, electric fields from outside the heliosphere will be shielded by it.
Where do all the charged particles from solar wind and coronal mass ejections go? Are the charged particles a plasma with a net neutral charge, or are they biased towards positive or negative? Is this the stuff that makes up the heliosphere?
Voyager is now at the edge of the heliosphere. Hopefully it will be able to make some measurements related to these questions once it has passed the boundary of the solar system.
I agree with basically everything democedes and pheonix1012 said, who said it better than I could, for sure.
I'd like to point out one statement, though:
"we can SEE the massive gas ejections from black holes and have pictures of the x-ray and gamma rays being shot from a black hole."
This technically isn't true. Nothing "escapes" a black hole, hence its name. However, Hawking predicts Hawking radition (black body radiation), but the problem is, the more massive the black hole, the less it actually radiates. So any black holes we're familiar with are sufficiently massive that anything emitted from them is simply not detectable with current instruments.
So literally, to my knowledge, the only means we have of identifying them is by their gravitational influence on objects around them or by viewing their quasars, which are specific to black holes, but also I believe relatively rare, if ridiculously luminous.
Not trying to give credence to the argument that black holes don't exist, but one can't deny that they're ridiculously difficult to observe.