quote:The two most important types of spacetime singularities are curvature singularities and conical singularities. Singularities can also be divided according to whether they are covered by an event horizon or not (naked singularities). According to general relativity, the initial state of the universe, at the beginning of the Big Bang, was a singularity.
Some of the stuff you're linking to is pretty clear, and I'm sure all of us reading your posts are pretty puzzled why you keep misinterpreting it. But some of the other stuff you're pointing to does seem fairly easy to misinterpret. It's not uncommon to see references to a singularity as if physicists believed it were something real when all the word is really doing is acting as a stand-in for the term "something we haven't figured out yet." That's what your Gravitational Singularity link at Wikipedia meant when it said in the part you quoted:
"According to general relativity, the initial state of the universe, at the beginning of the Big Bang, was a singularity."
You can tell that they didn't intend for you to interpret their reference to the singularity as something real by this sentence that follows, which you chose not to quote:
"Both general relativity and quantum mechanics break down in describing the Big Bang, but in general, quantum mechanics does not permit particles to inhabit a space smaller than their wavelengths."
In case this isn't clear, Wikipedia is saying that quantum mechanics doesn't allow particles to shrink to zero size, because the lower limit on their size is their wavelength, which is non-zero. Something that has a non-zero size cannot have an infinite density.
The word "singularity" is being used in different ways by different writers because of different contexts. In some cases they're writing about the hypothetical singularity of infinite density that is a theoretical construct and that we don't believe exists. In other cases they're using the term "singularity" to refer to the unsolved theoretical problem of what happens when one approaches T=0 at the beginning of the universe, or approaches the center of a black hole.
Black holes and singularities are two different things. In your reading perhaps you came across references to "naked singularities," those which exist independent of a black hole (though keep in mind again that singularities of infinite density are at this point theoretical abstractions and not thought to be real). Obviously if a singularity can exist independently of a black hole it can't be the same thing as a black hole.
Given what we know about quantum mechanics, neither singularities nor naked singularities exist in the sense of objects of infinite density, though since science is tentative that cannot be a final answer since there are no final answers in science. But do they exist as theoretical abstractions? Most certainly, which is why you keep seeing references that you think are referring to something scientists think is a real object.
Scientists don't believe that objects of infinite density actually exist in our universe. They believe that general relativity and quantum mechanics must be used together to solve the problem of what happened around T=0 and at the center of black holes, but they don't know how to combine these two different theories yet. I've mentioned a couple times that a number of theories has been proposed (quantum gravity that you once mentioned is one of them), but none has yet won out over the others.
And let's not forget this one: Plasmas have a roughly neutral net charge.
I somehow didn't receive the notice of summation mode, and my admin permissions means I was allowed to respond to justatruthseeker. I've modified this over to a summation.
Here's a list of things JustATruthSeeker was wrong about:
Normal matter is around 4.9% of the universe, not .13%.
Dark matter and dark energy actually comprise approximately 95.1% of the universe, not 99.86%. JustATruthSeeker was confusing the universe with our solar system. His 99.86% figure is the percentage of our solar system's total mass that resides in the sun.
Plasma cannot be responsible for keeping galaxies from flying apart because a plasma is normal matter, and since normal matter makes up only 4.9% of the universe there isn't enough of it. Like everything else in the universe, plasmas obey all physical laws, including those relating to gravity.
Black holes and singularities are not the same thing.
It is singularities that scientists believe aren't real, not black holes.
Plasma's are roughly electrically neutral. I can only guess that JustATruthSeeker is operating under the misimpression that a plasma is a cloud of particles all with the same charge, such as a cloud of electrons or a could of protons. It isn't. A plasma is a cloud of both positively and negatively charged particles, approximately equal number.