Skip to comments.Astronomers Celebrate Reliable Measure of Dark Matter
Posted on 10/30/2001 5:19:42 AM PST by callisto
Scientists are closer than ever to balancing the checkbook of cosmic matter. This is because two recent independent measurements of normal matter in the universe are in agreement. The results further strengthen the case for the Big Bang theory and for the nature of the universe as astronomers understand it today.
The universe contains normal atomic matter, what makes you, your dog, the stars, and everything in between. Normal matter is what Carl Sagan was talking about when he said we are all star-stuff.
But in addition to star-stuff, there is invisible dark matter that is known only because the universe is denser than normal matter alone, as evidenced by how structures, like clusters of galaxies, are bound together by gravity. Even individual galaxies don't have enough normal matter in them -- that which can be directly detected -- to keep them from simply flying apart.
Now, through different measurements of conditions existing at the very start of time, astronomers are beginning to see the light.
"There is more than one way of measuring the total amount of matter in the universe," said astronomer Brian Fields from the Center for Theoretical Astrophysics at the University of Illinois, Urbana-Champaign. "And if you have an idea of how much normal stuff there is to all the universe, then you know how much other stuff there is, too."
|Creation of normal matter|
All the "normal stuff" is thought to have been made in two steps, one occurring when the universe was roughly three minutes old, and the other some 300,000 years later.
According to the leading theory, an enormous nuclear explosion called the Big Bang happened 13 billion to 15 billion years ago. From it, the universe appeared in an instant, but as a billion-degree mess of neutrons, protons and electrons. The explosion was so energetic that nothing could come together close enough, for long enough, to form atoms. But the universe expanded and cooled so rapidly that within three minutes protons and neutrons bonded in twos and fours, and formed all the atomic nuclei in the universe. This Big Bang Nucleosynthesis determined how much normal matter would ever exist.
Just how much matter that was can be estimated from observing the most recently formed stars and galaxies, because they are fueled by the hydrogen atoms formed from those original nuclei of twos.
Fields explained that young stars, like our Sun, are just now fusing that original hydrogen into helium whereas older stars fuse helium into oxygen and iron. Because the hydrogen fuel has not been converted, scientists are able to measure the proportion of original normal matter to dark matter.
"Stars change the amount of hydrogen and helium in the universe," he said, "and we want to know what the Big Bang did. So we have to find places where pollution from stars is minimal" to estimate the original amounts of normal and dark matter.
But before any stars could form, hydrogen atoms had to exist. This took 300,000 years after the Big Bang Nucleosynthesis the universe had to cool down enough so that electrons could bind with the nuclei.
Once this happened, there was a curious side effect: the creation of light in the Universe. Unbound electrons scattered the UV radiation from the Big Bang, but once the electrons were bound, the radiation was allowed uniform movement, thus, light was finally released in the young cosmos.
This light has existed since then, travelling along the edge of the universe, stretching and weakening into a still measurable microwave radiation, called the Cosmic Microwave Background, or CMB as astronomers call it.
At the time of the original release of light, dark matter had congregated in clumps, which created small fields of gravity that eventually pulled in normal matter as well. Images of the CMB are therefore mostly smooth, but have spots, or wiggles, of slight variation, a result of the dark and normal matter pooling together.
"The nature of these 'wiggles' is basically saying how the normal matter was responding to that crazy dark matter," explained Fields, "by amplifying the places where the extra density was."
The CMB, most recently measured by highly sensitive probes in Antarctica, therefore gives a detailed measure of the proportion of normal to dark matter.
Phenomenally, both the measurements of young galaxies and of the cosmic microwave background showed that normal matter makes up just one-tenth of the universe. The rest must be dark matter, researchers say. Fields, who wrote about this astronomical agreement in the Oct. 19 issue of the journal Science, explained why this is causing astronomers to "bring out the bubbly."
"It didn't have to be true," Fields explained, "because they're completely independent things. It's just gorgeous that they agree with each other."
Earlier studies had showed that dark matter made up anywhere from 85 to 95 percent of the universe. Only now do the two different measures of dark matter agree. Now, 90 percent of everything is known to be virtually nothing.
"Normal matter is what Carl Sagan was talking about when he said we are all star-stuff."
What does that have to do with anything?
First off, if all the matter in the universe had ever been in one place (i.e. prior to the "big bang(TM)"), it would have amounted to the biggest black hole imaginable and nothing would ever have blasted its way out of that.
Second, if this "dark matter(TM)" were actually 90% of the mass of the universe, you'd be vacuuming it off your carpets every day, and not just five or ten vacuum-cleaner bags either. All of the conjecture about MACHOs, WIMPs (Weakly Interacting Massive Particles) and other sundry forms of dark matter are a bunch of BS. What all of that stuff amounts to and a much better acronym for all of it is Fabricated Ad-hoc Inventions Repeatedly Invoked in an Effort to Defend Untenable Scientific Theories, or FAIRIE DUST.
The whole thing is a load of BS. Astronomers and cosmologists have painted themselves into a total box by trying to insist that gravity chiefly governs the cosmos while anybody with an iota of common sense can look at spiral galaxies and similar cosmic phenomena and tell that he is seeing electrical, electromagnetic, and plasma phenomena. The notion of an expanding universe and a "big bang(TM)" are nothing more than logical requirements of a broken theory and a misinterpretation of redshift.
Eureka! I think you've discovered the secret.
Once this happened, there was a curious side effect: the creation of light in the Universe. Unbound electrons scattered the UV radiation from the Big Bang, but once the electrons were bound, the radiation was allowed uniform movement, thus, light was finally released in the young cosmos."
"1. In the beginning God created the heaven and the earth. 2.And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.3.And God said, Let there be light: and there was light. 4. And God saw the light, that it was good: and God divided the light from the darkness. 5. And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day."
Cosmology, with the Big Bang Theory postulating all of creation coming out of essentially nothing, in fact, supports more and more, the Old Testament. The creation of light after darkness carries this one step further. Atheistic cosmologists are VERY uncomfortable with the Big Bang Theory.
Into authoritarianism, you say? Next time you pass through Virginia, be mindful of these laws, all still technically in force:
Not only is it illegal to have sex with the lights on, one may not have sex in any position other than missionary.
There is a state law prohibiting "corrupt practices of bribery by any person other than candidates."
It is illegal to spit on sidewalk.
If one is not married, it is illegal for him to have sexual relations.
You may not have oral or anal sex.
Police radar detectors are illegal.
Citizens must honk their horn while passing other cars.
Children are not to go trick-or-treating on Halloween.
It is illegal to tickle women.
Be sure to honk as you go whizzing through the speed trap -- I'm sure the judge will understand your position.
You might want to check out Dumb Laws to be sure that you faithfully maintain your law-abiding standards. Or perhaps you insist that people obey only those laws you agree with? ;-)
Yeah. Any fool can plainly see your wisdom.
Not at all. It would be that exceedingly rare Biblical-literalist cosmologist who's having difficulties reconciling his beliefs, for time itself begins with the Big Bang.
There is no such thing as a time "before" the Big Bang when God could roll up his sleeves to do His creating.
...one of those religous, creationist, Bible quoting, begatting, and on the other hand, heavy math, quark quoting, over everyone elses heads ,with a heavy emphasis on theorical equations that makes Greek an easy read, resulting in someone calling someone else a Nazi threads.Cosmology and theoretical physics tend to bring that out in people, for some reason. LOL.
"Hmmm...that's not gonna work....how about we say that the universe is made up of...eleven dimensions....yeah! That's the ticket!...and uh...ummm....all but say.....four of them...disappeared after the big bang.....yeah...no, wait...they CURLED UP!....yeah, that's it!...they curled up into....into.....nothing!...something so small it can't be measured...yeah!....There! I think this will convince the Journal Nature!....(if I could only remember the question...)"