Don't Believe in Black Holes? Then what's THIS?

"Why it is that of all the billions and billions of strange objects in the Cosmos -- novas, quasars, pulsars, black holes -- you are beyond doubt the strangest?" -Walker Percy

Black holes. You've all heard them before, and you can visualize them pretty easily. How so? Start by thinking about the Earth.

Held together by the immense force of gravity, the Earth is a difficult world to leave.

What exactly do I mean by that?

It takes a tremendous amount of energy to get off of the planet Earth. If you were at the surface of the Earth, you'd have to be moving at around 40,000 km/hr (or 25,000 mi/hr) to escape from the Earth's gravity!

Not even a patriot missile, above, has the juice to escape from the Earth.

A Saturn V rocket could do it, though. In fact, we've sent quite a few objects out of Earth's gravity, and even a couple out of the Solar System itself!

But what if you made something so massive and so dense that, forgetting about rockets for a minute, not even light could escape from it! What would that do?

Image credit: Alain Riazuelo.

Well, in theory, that would be a black hole. But how would we know, for certain, that an object was a black hole?

Well, we'd have to get an object that emitted no light, that was super-massive, and that we could, with great certainty, exclude all other possibilities.

There's one surefire place to look.

Image credit: Rainer Schödel.

Go to the center of our galaxy! If there's one place in space where we expect there to be a bigger concentration of mass close by than any other, it's the center of our spiral galaxy. After all, looking at other spiral galaxies, it's pretty obvious that's where the greatest, largest, densest area lives.

Well, we look at the center of our galaxy, and, unsurprisingly, there are a bunch of stars there. But, as astronomers, we know the virtue of being patient.

Imagine taking the very center of the galaxy, and watching the innermost stars over the timespan of years.

What do you find? A massive star making a beautiful elliptical orbit -- just like Kepler predicts -- with a very heavy mass at one point. What is that mass? Between 2.7 and 4.0 million Suns. But where's the light?

There is none!

But you know scientists. We're never convinced by one example. So we turn to the UCLA galactic center group, where they've been tracking many stars, over more than a decade, in their orbits.

(It may take a bit to load; movie download here.)

In fact, they have a slew of videos and images for download, but perhaps the most convincing image (cropped by me) is this one.

When you can see all of these different stars, and they're all orbiting the same point, and that "point" has millions of Solar Masses there, what else could it be?

Not only does it have to be a black hole, but there are no other ideas even out there. So if you didn't believe in black holes, I hope this convinces you, and if you aren't convinced, then please, tell me what that thing is!

More like this

Not only does it have to be a black hole, but there are no other ideas even out there.

So it is an object or region of space so dense that not even ideas can escape? Wow :)

Another random observation: Astrology must be a real pain there, with stars moving so very, very fast. In a little more seriousness, would it be an impressive sight to have the night sky move so much (if there even is a night sky with so many stars so close)?

I'm certainly not the be-all and end-all of logical thinking... but isn't this just an argument from personal incredulity?

By Shane Dalzell (not verified) on 08 Dec 2010 #permalink

I certainly believe in event horizons. But I'm not entirely certain about singularities.

So if you didn't believe in black holes, I hope this convinces you, and if you aren't convinced, then please, tell me what that thing is!


Well, I'm pretty sure it is as you say, but if I were to use my imagination with absolutly no evidence to back it up...hmmm.

If the areas that exhibit black hole tendencies were actually the Lagrangian points of a multiple universe system would we still call them black holes?

Of course you may have to evolve the super-clusters a few billion years to get the super-massive blackholes so this concept would be easier to see.

Well there's my spur of the moment, off the cuff,hypothetical pie in the sky idea.

Can't wait to see that! paper.

Regarding first picture; We have a beautiful home.

By Sphere Coupler (not verified) on 08 Dec 2010 #permalink

I guess I'm a little different than most folks, when I think of black holes {Gollums song by Emiliana Torrini} starts playing in my head. Don't watch the video, just listen to the words and music as you think about black holes.
Works for me.


By Sphere Coupler (not verified) on 08 Dec 2010 #permalink

Hi, jsut one big doubt, I see the stars orbiting on their own orbits, but I mean, all orbits seem quite different to me, there´s no central point they are orbiting around... or is there?

At the risk of being a sceptic - it really could fit a number of possibilities.

It would have to be something that is:

1. Very massive (4 million solar masses)
2. Doesn't glow

Let's look at something very dense and stable - lead.
It has a density of around 11,340 kg per cubic meter

So if we type this into google:

[ cube root of ((4 million x 1 solar mass) / (11340 kg per cubic metre) * 3 / (4 * PI)) in AU ] it will calculate the radius of a lead sphere (in AUs) that will give 4 million solar masses..

The answer? About 0.4 AUs

So, a lead sphere that was about the diameter of the earth's orbit would fulfil both criteria. (I appreciate that Uranium would be even better)

So the question is - what measurements have we taken that would invalidate this 'big lead ball' model?

Sure - a big lead ball might not fit our current model of stellar formation ... but I'm interested in whether it contradicts our measurements?

(PS: I'm assuming that there are some measurements which would be different - just that the data given might match either model. I'm not seriously suggesting that lead balls can be found lying around the place.)

But I'm not entirely certain about singularities.

I am also quite unconvinced that mathematical artifacts of General Relativity (=singularities) trump Quantum Mechanics (discreteness of space-time rules out singularities). Maybe Ethan could give us the view of an astrophysicist on this?

@wega: The ellipses are not seen face-on, so the focus does not seem to be where we would expect it to be if they were. (Similar problem occurs with, for example, Sirius B orbiting Sirius A).

My 2-bits' worth: Pluto an Charon both follow Keplerian ellipses, but around a point in space between them; there's no object there. Same with Acen A/Acen B. And numerous globular clusters. Perhaps the stars are merely orbiting the group's overall center of mass. It's a falsifiable hypothesis: if it is correct, the center of mass (orbital focus) will move predictably over time in response to the changing locations of the stars (too erratically to be consistent with a moving massive object). If it doesn't, the hypothesis is dead.

J.B.: Can't be HoG, that belongs to Maradonna.;-)

So, a lead sphere that was about the diameter of the earth's orbit would fulfil both criteria. (I appreciate that Uranium would be even better)

Except that such a massive object would collapse under its own gravity. Matter is simply not solid enough to sustain such pressures.

Eski devletlerin yönetim anlayıÅı baskıydı.
Böyle giden bir iÅleyiÅe âdurâ diyebilmek için 1215 yılında Ä°ngiltere Kralına kabul ettirilen bildirge, Magna Charte (Magna Karta) Ä°nsan Hakları kavramının ilk belgesi sayılır. Ä°nsan hakları konusunda yayınlanan bir diÄer önemli bildirge, Amerikaâda yayınlanan BaÄımsızlık Bildirgesiâdir. Ãzgürlük, eÅitlik, kardeÅlik gibi kavramlar, 1789 yılında gerçekleÅen Fransız Devrimiânden sonra yayınlanan âÄ°nsan Hakları Bildirgesiânde gerçek yerini alacaktır.

Hi, jsut one big doubt, I see the stars orbiting on their own orbits, but I mean, all orbits seem quite different to me, there´s no central point they are orbiting around... or is there?

The Sun does not lie at the center of the Earth's elliptical orbit. It lies at one of the two focal points. That's how elliptical orbits work.

The Earth's orbit is almost circular, so both focal points actually lie inside the sun (one at the center of the sun, the other not); the orbits shown here are very far from circular, so that the black hole occupies only one of them.

By David MarjanoviÄ (not verified) on 09 Dec 2010 #permalink

Re #9 So the question is - what measurements have we taken that would invalidate this 'big lead ball' model?

I just took a rough measurement of the yellow orbit in the video, it appears to be less that 0.2 AU in diameter meaning that it orbits inside the hypothetical 0.4 AU lead ball. Perhaps the denser uranium ball would be small enough to accomodate a 0.2 AU orbit but a uranium pile of that size would either collapse into a nutron star/black hole or emit lots of light in the form of a massive nuclear explosion.

Also note that by definition the Earth's obit is 2.0 AU in diameter. 0.4 AU is roughly the diameter of Mercury's orbit.

a uranium pile of that size would either collapse into a nutron star/black hole

And so would a lead pile of that mass. Or indeed a pile of anything of that mass. We know the stability of atoms, and we have a pretty good grasp on the stability of neutrons. Anything with that mass within that little space instantly collapses to a black hole, period.

By David MarjanoviÄ (not verified) on 09 Dec 2010 #permalink

So ... how fast is S2 going? From your diagram I guess the orbital distance is about 0.01pc. If it makes an orbit in about 15 years, that averages out to be ~650km/s (compare to Earth's orbital velocity of about 30km/s). But what's the peak velocity?

By Zippy the Pinhead (not verified) on 09 Dec 2010 #permalink

You don't have to go to the galacatic center. The blue giant star HDE 226868 is much closer, and it is also orbiting a dark object much more massive then any neutron star can get. And it coincides with the position of a strong X-ray source.

By Birger Johansson (not verified) on 09 Dec 2010 #permalink

I thought the accretion disks of black holes would be quite bright (including in visible light). Shouldn't we see that?

I think that (it)

(it)meaning outflow

By Sphere Coupler (not verified) on 09 Dec 2010 #permalink

Lead in the solar system has an abundance by mass (per chemicool) of about 10 parts per billion. If the galactic lead abundance is roughly homogenous, the entire Milky Way, with a total mass of about half-a-trillion solar masses, contains an implied mass of lead in the range of 5000 solar masses, a roughly a factor of 1000 less than the mass of a central lead ball would have to be. Unless you're prepared to countenance a factor-of-1000 inhomogeneity, there exist reasonable obervational grounds for concluding there's no giant ball of lead there.

A geometry question--in the plane of an ellipse, the foci must always lie on the major axis. If you observe the ellipse in parallel projection out of the plane, the shape is still an ellipse. The question is: are the projected foci always still on the major axis of the projected ellipse?

By Andrew Foland (not verified) on 09 Dec 2010 #permalink

What's with S0-17 and S0-45? They appear to move in fairly straight lines at fairly constant speed close to the black hole. Are they just far out of the plane S0-2, S0-16, and the black hole are in?

Very impressive pictures, and I don't think it matters what's on the other side of the event horizon, a singularity or something else very dense, we can speculate, we can model, but we can never check. One question so, where does the momentum go when a proto-black hole finally collapses beyond it's event horizon? Does the singularity still spin?

If you 'don't' believe in black holes then you have to come up with another explanation for gravitational lensing and the old perihelion of Mercury problem other than General Relativity, and well, gravity itself. A black hole is only a difference of degree from gravitational lensing.

Re #9 So the question is - what measurements have we taken that would invalidate this 'big lead ball' model?

Aside from the mass problem a big lead ball, or uranium, or any matter, would reflect light, and thus, be visible. Or am I wrong here?

@ #24
"The question is: are the projected foci always still on the major axis of the projected ellipse?"

I don't have a proof for you, but the question intrigued me, so I drew an ellipse in AutoCAD, drew in the major radius, and then used the 3dRotate command to rotate it out of the direct plane of view, giving me something close to the projected ellipse you're asking about. It appears to me that the projected ellipse has different major and minor axes than the original ellipse. Since the original major axis and the major axis of the projected ellipse only cross at the point directly between the two foci, that would make it impossible for the original foci to be on the projected major axis. The projected foci, however, should be on the projected major axis, otherwise it wouldn't be much of an ellipse (that would kinda break the definition of an ellipse, no?).

I'd really like to see someone who knows more about this actually answer the question intelligently though. Autocad only uses center point, major/minor axis length, and rotation for its ellipses, so I'm not even entirely sure that it renders them true, especially when rotated away from the default plane.

Yes this is really excellent science.

I particularly like the images and explanation that our galactic center is very densely populated with stars and that the central most stars follow elliptical orbits around a massive unseen elliptical focal point. Thanks.

SGR A* sure smells like a black hole. Observations like these are essential to sniff out the mysteries of black holes. (blame Wheeler, he coined the name)

Nesxt, consider an astronomical scaling up, from galaxies to clustering of galaxies around voids, see here necklace of spiral galaxies:…

Now my questions and musings (arguing with myself):

--Q. Are there theoretically super supermassive black holes of suffiecient size to inhabit the center of clusters?
---A. Probably not, the upper limit of a black hole seems to be only an order of magnitude bigger than our Galaxy's SGR A*.

--Q. What about dark matter at the center of voids?
---A1. But I just find the idea of dark matter problematic.
----A2a. But if dark matter were antimatter and the voids were bubbles of antimatter expanding (i.e. antimatter gravitationally attracting backwards in time; which from our forward in time viewpoint looks like antimatter expanding).
---A2b. Yes, makes sense to me. An anti-matter bubble would gravitationally expand from our forward in time viewpoint. It would interact inertially with matter until it transformed from antimatter into matter at the outer edges of the bubble (voids).
---A2c. Thus antimatter white phenomenon (i.e. white holes) and matter black holes would be a kind of cosmic B-Z oscillating matter/antimatter gravitational reaction.
---A2d. Here is a video of a Belousov Zhabotinsky B-Z oscillating chemical reactions:
Do you see the cosmic analogy.
---A2e. Of course entropy in voids would be the reverse of in galaxies; and the big bang would become more problemmatic despite current thinking.
---A2f. So my big question, what evidence is coming from cosmic voids to prove or disprove that they were full of antimatter? And around the edges of the voids to suggest that antimatter is converting into matter? I really much prefer extra-spatial dimensions for doing all of this B-Z cosmic stuff; but this is were my thinking takes me today.

OK, I'll bite.

Imagine a body at the focus with an unusually strong negative electric charge, and the orbiting bodies with a positive charge.

You would need to assume some surprising things, such as a scarcity of ions in the region (which would mask the electrostatic forces) and some process to maintain the charge on the focal object, probably related to its central position. You would need the focal object large and strong enough not to the be ripped asunder as all the charges try to flee from one another. You need a process to maintain charges in the other bodies.

Or, you could leave out the central body and assume a magnetic field to produce the same forces on the (again) charged orbiting bodies. You wouldn't need to assume ion scarcity, then, or a process to concentrate charge at the focus. You need, instead, a magnetic field, presumably generated by the rotation of the galaxy, concentrated at very nearly a point.

Of course these are testable, and perhaps depend on increasingly odd assumptions (as odd as dark matter or inflation?), but that's what astrophysics is all about -- right?

I think it's probably a black hole, but it's absurd to say there are no other ideas out there.

Really, I'd rather read about features nobody has any good idea about, that nobody mentions in press releases because they're just too embarrassing.

By Nathan Myers (not verified) on 09 Dec 2010 #permalink

I'd like to see a 3D model of the movie. SO45 seems to move in a straight line just passing the black hole so I assume we are on plane with it's orbit which must be more round than this movie shows. Thank you for the article and interesting comment by all.

Shane asked, "I'm certainly not the be-all and end-all of logical thinking... but isn't this just an argument from personal incredulity?"

Nope, more like Occam's Razor, the idea that the simplest explanation that accounts for all the observations is the most likely to be correct. The observations suggest something ginormous in there. You could make a list of the kinds of objects we know about and eliminate the ones that don't work. What you're left with is a black hole. The thinking is not, "I don't understand how this works, therefore I think it's a black hole;" it is, "I plot all those elliptical orbits and they look like 4 million solar masses in one place. It's dark there. A conclusion that makes sense is a black hole."

djlactin, I have the intuition that if it were just the center of mass of a bunch of stars, the gravitational gradient of that arrangement would not permit those kinds of orbits. I don't think the stars in a galaxy behave like there was a single point source of all their gravity at their common center.

Another really beautiful aspect of the animations is that an obscure one of Kepler's Laws is so well illustrated: the stars sweep out equal areas in equal times. Look at the star that does a complete ellipse: When it's at its farthest, it's moving relatively slowly. But when it gets close, zowie! Look at it move! There's got to be a dense point source of gravity for that to work. (That contributes to my doubting it's just an ordinary stellar cluster.)

By Timberwoof (not verified) on 09 Dec 2010 #permalink

Sorry for the double post. Here's a solution to the projected-ellipse conundrum.

Draw an ellipse on a sheet of paper using the two-thumbtacks-and-string method. The thumbtacks are the foci, so draw a star at one of them. Hold up the piece of paper at various angles. Can you find an angle at which the star (and the other focus) is not at the focus of the distorted ellipse? (Looking at it from close up is cheating. Look at it from across the room to reduce distortion from perspective.

Photograph (with a log lens so the ellipse fills the image) and print the off-angle ellipses. See if you can draw those ellipses with the thumbtacks-and-string method.

I can already see that this fails. Turn the paper so that its foci are close together. You'd expect the orbit to become a circle but it does not; it becomes a different ellipse, one you cannot draw on your image plane with the thumbtacks-and-string method.

By Timberwoof (not verified) on 09 Dec 2010 #permalink


It became clear to me on my commute home tonight that the answer to my question is "no"--the projected foci need not lie on the major axis of the projection. (Though they do, of course, have to lie on the projection of the major axis!)

Imagine a moderately eccentric ellipse in a plane. Now imagine projection primarily along the direction of the major axis, just infinitesimally out of the plane. The original major axis in this projection becomes very short, and forms the minor axis of the projected ellipse. The original minor axis (at a right angle) remains invariant and becomes the new major axis of the projected ellipse. The projected foci, however, both lie on the projection of the major axis, which is the minor axis of the projected ellipse.

The question comes up because the putative black hole position is clearly NOT on the major axis of SO-20's orbit. (Whereas it actually does seem to be pretty well for all the others.) But the answer to above being "no" means that it's possible that the orbit of SO-20 is being viewed from here on earth at an angle to the orbital plane.

By Andrew Foland (not verified) on 09 Dec 2010 #permalink

Hi David @ #18, yes I realise the lead ball would also collapse, that's why I called it a "hypothetical lead ball", my point with a similar hypothetical uranium ball was that it would emit light. ie: ignoring gavitational collapse there is no substance you can make such a massive ball from that would A. Not emmit light and B. Fit inside the yellow orbit.

But as I try to imagine the foci of these ellipses, they seem to suggest that the massive object is in various places, not a single point. So what's going on?

By MadScientist (not verified) on 10 Dec 2010 #permalink


Perhaps you are thinking in the two dimensions you are seeing, rather than the three that are actually there? We cannot (yet, due to technological limitations only) measure the motions of these stars in the radial direction: towards or away from us.

Throw in the third dimension, and every star up there can have the "star" in the second to last picture as its focus.

For all who wonder about why the foci of the orbits around SgrA* do not appear to coincide (Wikipedia):

Sirius B orbit around Sirius A, as seen from our perspective:

Apparent and real orbit of alpha Centauri B around alpha Centauri A:

A circle seems elliptical if you view it on an angle; similarly, an ellipse can seem circular it you view it from the 'correct' angle. An ellipse seems like a different ellipse if you look at it from any angle other than the normal.

In fact, contrary to what Ethan says, it's relatively easy to deconstruct the true ellipse from the apparent one: "just" tweak the viewing angle until the focus corresponds to (the obviously correct) one of the ellipse. A 3D representation would be way cool!

p.s. My earlier alternative hypothesis to refute the "existence" of SgrA* was "devil's advocate".

Thinking further on my "hypothetical pie in the sky" idea
in comment #6...

IF and that's a big if, you could envision a river where a rock lies just below the surface of a fast moving flow of water, you would see vortex (whirlpools)set up that would break away from the rock area and float downstream depending on the rate of flow, size of rock, depth of rock in medium (water).

Now assume a almost homogeneous (in every way)primordial SINGLE Universe where there are millions of small Lagrangian points created by the overall barycenter of all mass, Matter would tend to migrate to these center of mass points (because matter moves, it always moves)until the point is in equilibrium with the rest of the Universe.{no BH).

But if there were more than one Universe and they were fixed in relation to our Universe, and also assume that the combined relationship of all these Universes gave us the constants and properties that we experience.

All the combined forces of these unseen Universes set up a fixed Lagrangian point within our Universe (rock) and since matter moves (river), vortex (whirlpools)are set up at this fixed point and break away only to continue the collapse as we understand it as Black Hole Dynamics.Many points of black hole matter could initially be made as the homogeneous matter moves past the Lagrangian point(rock).

This of course is pure speculation as to the initial starting point in a primordial Universe for a BH and many assumptions would have to be made and everyone knows when you ass can be made out of you and me.



By Sphere Coupler (not verified) on 11 Dec 2010 #permalink

@Dunc, David MarjanoviÄ, anyone else who got after the "lead ball":

I don't think that the point of the lead ball was that it had to be ordinary matter, just that anything as heavy as lead (down to ~2.4 x weight of lead actually) could fit in 1 AU and weigh 4 million solar masses.

Nitpicking about what it's made of is like dismissing Zeno's dichotomy with lim x>inf 1 / 2 ^x. it works, but no one could prove it until Weierstrass et al.

Either saying it must be a black hole or that it can't be requires more knowledge than we currently possess. A black hole looks like a pretty neat solution, yet the math doesn't all work.

So, I say that there could be thousands of kinds of stable material far heavier than lead, or more than one kind of gravitational geometry. Who knows?

Just keep an open mind, and avoid dogma. The answer is likely out there, but don't be sad if you don't live to see it.

Regardless, this is beautiful stuff, IMO.

Surd1618, dogma? What assertions of truth presented without evidence are you talking about?

That's right; the math doesn't all work; that's the problem with black holes. As physicists who study this stuff have been saying, black holes cause a collision between quantum theory and general relativity. But that doesn't mean that black holes don't exist; it means that we don't understand what happens.

I'm not concerned about the elliptical orbits seen in the animations: The math to do this is well-understood by the graduate students working on the problem. They probably have a system worked out to plot positions of stars over time and derive all the parameters of the orbits.

So you have a hypothesis: "there could be thousands of kinds of stable material far heavier than lead". Well, probably not. Physicists smarter than I have been working on this problem, and it turns out there are not, and astronomers have observed objects that correspond to what physics predicts. For a complete discussion on this, you need to read up on white dwarf stars and neutron starts.

So using what we know (and admitting the things we don't know) about the behavior of matter under extreme gravity, the best explanation is still a black hole. If you want to say it's not, you need to present arguments that take into account what is known and not just claim that people are being dogmatic. Do you expect us to accept alternatives presented without thorough reasoning? That would seem to be a kind of dogma to me.

By Timberwoof (not verified) on 11 Dec 2010 #permalink

I know its unrelated, but have we ever observed stars disappearing into a black hole? Does the light output of that part of space suddenly drop?

OK, here's an idea from someone who has no scientific experience, but does have an active imagination.
Think Big Bang theory. Now think about the possibility of Parallel Universes. What if the "Black Holes" that we see (or assume are there), are actually portals to a Parallel Universe? If we're correct and Black Holes are incredible masses (from our own universe) squeezed into tiny dimensions, then maybe those masses are exploding out the other side (where we can't see), thus creating a 'Big Bang' in a Parallel Universe? OK, now let the more educated begin ripping my theory. :-)

@MMTR: That idea is actually already quite old, I'd estimate several decades (although I don't think that it can be supported by actual calculations). The only thing you should change that you shouldn't call these "explosions" in the "parallel universe" a "big bang" - because the big bang was not an explosion of matter outwards into an already existing space, but essentially the beginning of spacetime itself. The more usual name for such "explosions" you mean here is "white holes".

And on the other hand, the idea that new universes can "spawn" from already existing ones is also already rather old (I'd estimate about 20 years).

Bjoern- Thanks for the clarification. I always wondered if that idea was mine or if I had heard it at some point in my past and just forgotten. I do still think that the other side of Black Holes are portals to other universes. I have to believe that all that matter being sucked into them is going somewhere. I'm really fascinated by space, but my brain is not scientific enough to comprehend the more complex theories. I have to resort more to imagination....

no offence but this doesnt prove NEthing

Quasars are not singularities but vortices to universe center. That mass will realize all other matter suddenly and create next Big Bang.

By dddoouugg (not verified) on 18 Mar 2011 #permalink

just saying, and i havent looked anything up at all, i think that when something is sucked into a black hole that, looking at how slowly stars move compared to the whole galaxy, it could be forced out of time for many decades, centuries, or even millenia and it could come out of the other side numerous years later.

By ralph poodle (not verified) on 30 Apr 2011 #permalink

There are not black holes out there. They simply are not referenced in the Bible. Everyone knows that is the most authoritative book. Don't you think if God had made Black Holes, Jesus would be talking about them in Nazareth? And if Black Holes are so dense light can't get out, then what about God? Can God get out or does he just get sucked in like some kind of drain hole? Does God need to keep His Distance from them?

I remember when the Earth was flat and all the planets just went around in elipses. Can't you people just be satisfied with that? Why do you have to go mix things up? Have you been talking with The Devil?