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Quasars, the Earlyverse, Dark Matter and Antigravity

Henningjohnathan

20:20 / 12.07.06

Recently musing on Quasars. I heard that these are distant objects "powered by" black holes at their center. In the article I read it mentioned that the light from some Quasars was 12 Billion Light Years away.

Since I've also read the the universe is just a little older than 13 billion years, that seems to me to imply that when we "look" at that quasar we are seeing an object that existed only one billion or so years after the Big Bang.

At that point the universe would only be around 2 billion light years across, meaning that all the matter and energy in the universe would be relatively much more compressed than it is now. Also, this led me to think that Quasars probably predate most if not all the stars and galaxies in the universe. Is it flawed to think that perhaps quasars are in fact the seeds for stars and galaxies?

Imagine if that black hole "powering" the quasar is in fact being torn apart by a kind of antigravitational force that caused the big bang. While the universe still has a relatively small diameter, the repellant force is still quite strong, but as all the matter and energy of the universe expands, its influence grows imperceptibly weaker.

Could there be an antigravitational force that we haven't yet discovered that could cause the big bang, reverse black holes, but is only perceptible if you take into account the entire mass of the universe? Could an undiscovered supra-scale force be behind the inexplicable (and possibly erroneous) gravitational effects that leads scientists to believe there must be vast amounts of unseen "dark matter" to account for it.

01:51 / 13.07.06

Henningjonathan, perhaps you might try reading wikipedia sometime. Your threads here are very difficult to answer because they are like asking why rainbows don't just fly away because they have no mass- so full of fundamental misunderstandings they are almost meaningless. Try the 'Stupid Science Questions' thread instead of starting new ones every time please.

This time, I'm providing links on basic astronomy and cosmology which will answer your question, next time expect short shrift.

Recently musing on Quasars.
They are probably supermassive black holes.

Is it flawed to think that perhaps quasars are in fact the seeds for stars and galaxies?
Yes. They are bigger. Is it flawed to think continents are the seeds of pebbles?

Imagine if that black hole "powering" the quasar is in fact being torn apart by a kind of antigravitational force that caused the big bang.
What does this even mean? The antigravitational force that caused the Big Bang? See my comment above on why rainbows don't fly away.

Could there be an antigravitational force that we haven't yet discovered that could cause the big bang, reverse black holes, but is only perceptible if you take into account the entire mass of the universe?
No. No there couldn't.

12:19 / 13.07.06

Actually, there's something to the seeding-galaxies idea -- last paragraph here:
In the 1980s, unified models were developed in which quasars were viewed as simply a class of active galaxies, and a general consensus has emerged that in many cases it is simply the viewing angle that distinguishes them from other classes, such as blazars and radio galaxies. The huge luminosity of quasars is believed to be a result of friction caused by gas and dust falling into the accretion discs of supermassive black holes, which can convert about half of the mass of an object into energy as compared to a few percent for nuclear fusion processes.

This mechanism is also believed to explain why quasars were more common in the early universe, as this energy production ends when the supermassive black hole consumes all of the gas and dust near it. This means that it is possible that most galaxies, including our own Milky Way, have gone through an active stage (appearing as a quasar or some other class of active galaxy depending on black hole mass and accretion rate) and are now quiescent because they lack a supply of matter to feed into their central black holes to generate radiation.

...and this discussion of Population III stars might be of interest. (Using quasar emission spectra to get an idea of the elements in the early universe.)

In general, though, the idea of an undiscovered anti-gravitational force is, well, needlessly complicated and doesn't really follow. (As if gravity wasn't complicated enough....)

Henningjohnathan

14:01 / 13.07.06

If there is no anti-gravitational force, then what causes the expansion of the big bang? Essentially, if all matter attracts itself, then what overcame the gravitational attraction of supermassive objects in the early universe? All motion is the result of the effect of a force, right?

Henningjohnathan

14:07 / 13.07.06

Here's an interesting connection:
http://www.guardian.co.uk/science/story/0,,1768191,00.html
"The Cosmological Constant is a mathematical representation of the energy of empty space, also known as "dark energy", which exerts a kind of anti-gravity force pushing galaxies apart at an accelerating rate."

Why couldn't "dark energy" or "dark matter" simply be the effect of a force inherent to normal matter but one that we can't perceive on our scale? Its effects are only realized when you look at the universe from the perspective of masses the size of galaxies and distances of billions of light years.

14:39 / 13.07.06

what causes the expansion of the big bang?

God or nothing or spaghetti hoops, we don't (can't?) know. In the article you refer to you may notice this- "There doesn't have to be a beginning of time. According to our theory, the universe may be infinitely old and infinitely large."
"the new theory suggests it is a cyclic event that consists of repeating big bangs."

The cosmological constant is the energy density of empty space and Einstein called it his biggest blunder. Space is expanding, if I understand it correctly, while dark energy is hypothetical as yet. I prefer "quintessence, a dynamic field whose energy density can vary in time and space" to the cosmo constant personally.

grant that's cool about the dead quasars being the nuclei of galaxies like ours, I stand corrected. Posting in frustration I'm afraid.

15:31 / 13.07.06

Why couldn't "dark energy" or "dark matter" simply be the effect of a force inherent to normal matter but one that we can't perceive on our scale?

That's what the definition of "dark energy" and "dark matter" is. Ordinary stuff we can't perceive because of scale (or, if you prefer, distances between things). I can't see where the "force" is necessary.

The problem might be that "force" has a specific meaning in physics that isn't just "something that does something."

Henningjohnathan

15:38 / 13.07.06

Hey, you're right, I should switch to the Stupid Science questions.

15:45 / 13.07.06

Space is expanding, if I understand it correctly

Yes. This is the source of a lot of misconceptions about the Big Bang -- that somehow there was this object called a singularity that was floating in infinite space and that somehow blew up into it, like a firecracker going off in an empty room. That's wrong.

The Big Bang is where space comes from -- we're still living inside the explosion, in a way. There was no room, no emptiness... no dimensions, no distance, no gravity, no force.

Henningjohnathan

15:55 / 13.07.06

That's what the definition of "dark energy" and "dark matter" is. Ordinary stuff we can't perceive because of scale (or, if you prefer, distances between things). I can't see where the "force" is necessary.

The problem might be that "force" has a specific meaning in physics that isn't just "something that does something."
Maybe I misunderstand it, but when I looked up Dark Energy and Dark Matter, it described it as something other than what anything I can see or touch is made from. As an unidentified form of energy and matter that simply "must exist" to explain the motion of the universe, not because anyone has actually found the stuff.

My question really has to do with the idea that maybe this "dark stuff" doesn't have to exist if there is a repellent force opposing gravity that doesn't have a perceptible effect on local events but does have a significant effect (even stronger than gravity) on events that involve galactic sized concentrations of matter.

Henningjohnathan

16:41 / 13.07.06

BTW, I now see where the Quasar becoming a galaxy plays against the idea that the black hole spewed forth the galactic matter.

The black hole still exists but is in the center of the resultant galaxy.

Thanks.

10:37 / 14.07.06

"Dark Matter, it described it as something other than what anything I can see or touch is made from."

I see where the misunderstanding arises- dark matter is just anything that doesn't emit light. You and I are made of dark matter, all planets, asteroids, comets etc. are dark matter, stars aren't.
The thing about dark matter is this as far as I know, hope I can make it clear...

"Estimates of the amount of matter present in galaxies, based on gravitational effects, consistently suggest that there is far more matter than is directly observable."

If most of the matter in our solar system is concentrated in the Sun (it is), and our system is relatively typicalof the universe (i.e. mostly space with clumps of matter) then most matter in the universe should be bright and visible. The universe should be stars in empty space with some little bits of dark stuff floating about. But astronomical observations show that it isn't so.

The dark matter component has vastly more mass than the "visible" component of the universe

This is the tricky bit, only 4% of the universe is stars and other stuff we can see. About 22% is probably dark matter (and about 74% is probably 'dark energy' but that's another issue). So what is this stuff? Where is it all?
The answer is we just don't know and are desperately trying to figure it out.
"The terms . . . 'dark matter' and 'dark energy,' serve mainly as expressions of our ignorance", much as the marking of early maps with 'Terra Incognita'." (D.B Cline)

10:44 / 14.07.06

In a tinier nutshell, 99.86% of our solar system's known mass is in the Sun. But only 4% of the universe is like the Sun, so there would have to be 25 invisible suns worth of mass/energy to balance it out to fit our observations of gravity.
Where is it all? That's the mystery of dark matter, and all the really complicated stuff is an attempt to explain it.