Yet More Cosmology Questions From Me.

Re: Yet More Cosmology Questions From Me.

I believe that 13.3bya is projected to be the birth of the Universe, so our standard cosmological models do not go back further than that.

Inflation happened after the beginning, not before it.


Space itself is "inflating" even now. This is not the same thing as the "Inflation Event" which is part of the BB model, but it is a better description of what is currently called the "expansion of the Universe".

It's important to remember that nothing is moving away from us with any velocity, it's moving away from us because it's being carried along in the inflating space which permeates everything.


First of all, you need to differentiate Dark Matter from Dark Energy.

Dark Matter is chunks of stuff, either microscopic or simply dark, which we can not see with our instruments. The only thing mysterious about Dark Matter currently is, what "stuff" is it, and how much of each type of "stuff" composes the bulk of Dark Matter.

Dark Energy is an entirely different mystery. Dark Energy is apparently an aspect of physics which we have yet to grasp. One effect of Dark Energy is to cause the Universe to not only expand (or inflate), but to cause it to inflate faster and faster as time passes. Dark Energy comprises the largest component of the energy and structural equations which are used to define the current model.

Dark Matter is a curiosity.

Dark Energy is a revelation waiting to happen.


It shouldn't be surprising that we can not see dark stuff in a dark sky, only the shiny stars stand out. But stars and planets coalesce from vast interstellar clouds. For every star we see, there must exist some remnant of the interstellar cloud which formed it and didn't fall into the star (planets are one piece of this) and there's a good chance that the bulk of the cloud material is dispersed rather coalesced. Then of course, there are black holes and brown dwarfs and elementary particles of minute mass but incredible numbers.

Astronomers put the age of the universe at 13.7 billion years, but they can only see as far as 13.3 billion years with their telescopes. The first 0.4 billions years (or so they claim), is what I am asking about. How did they know what happened earlier than 13.3 billion years ago? Or if there was a universe before then, or how old the universe is.

I know the difference between space expanding now and the Inflation period, the supposed first 0.4 billion years of the universe (see above). I think you're not getting what I am trying to say rosborne979. Astronomers say the further away a galaxy is from us, the faster it is moving away from us, do to the exansion of space. But, the further away a galaxy is from us, the further back in time we are observing it, so aren't they seeing that galaxies further back in time are moving faster, and thus the expansion is slowing down?

I understand why dark matter came about, if you look at the motion of galaxies etc., but why dark energy? What's it for? Why not a new force or two? Dark matter must be far more prevelant in the universe than the stuff they can see. Planets cannot get too large or they become stars, so how much really can be dark matter? Really not on the scale they talk about.
If they get really large they must have gravatational effects that can be observed, well, where are they?

Ok, sorry. I didn't realize you had the basics of this down already.


I think these things are all predictions of "The Model". Currently there is a standard model for the physics of the universe based on the Big Bang. That model includes an inflation event, and predicts the energy state of elementary particles back to the initial point in time. As new evidence is accumulated, the model is refined in more and more detail, but some of the things we "know" are simply predictions of the model.


I think when they say "the further away it is, the faster it is moving away from us" it has more to do with the fact that there is more space between us and whatever we're observing. Since there is more space between us and the distant object, there is more expansion which makes things appear to be moving away from us faster.


I think that's what "Dark Energy" will turn out to be; a new force. I don't know why they call it Dark Energy. Maybe because they can't define it as a force yet. Also, it might not be a 'force' as we know understand forces. It may be something radically different. I suspect that once we understand Dark Energy, we will have to alter the Standard Cosmological Model radically to accommodate it.


We know what some of the Dark Matter is. Planets and gasses and dust and stray atoms and black holes and brown dwarfs and probably a slew of stuff we don't know about yet. I think the big discussion with Dark Matter is the proportions of the stuff. Some people think it's mostly black holes, large and small. Others think it's mostly neutrino's (or some other minutely massive particle) which permeate all of space.

I'm not sure how the energy equations of the model differentiate between the predicted amounts of Dark Energy versus Dark Matter.


Some are. Black holes are being discovered all the time, and large ones occupy the center of every galaxy.

Also, the rotation of galaxies indicate that much of their mass is contained outside of the visible boundary (probably huge swaths of dust). Somewhere I saw a picture of one galaxy in front of another, and you could see the dark matter surrounding the galaxy in front. I'll try to find the image. It was probably on APOD somewhere.

Is that closer to answering your questions?

As far as signs of dark matter, I believe they've also located galaxies with plasma shooting between them whose plasma exchange appears to be affected by this "dark matter." I'll look it up the next time I have access to my library.

Overlapping Galaxies

Dark Matter map

The Standard Model

Actually there was nothing before when there was something assuming before has any meaning. Which is being dicussed at great expense in the philosophy departments of the world's universities as we post.

There are rather too many "I believes" on here for my liking.

I believe for every drop of rain that falls
A flower grows.

I realise I'm kidding myself but it sounds nice don't you think? And that's not to be sneezed at in this day and age.

Hey, my "I believes" have only been coming out with a promise of fact checking, and it just so happens that it's one of two "I believe"s in the topic, both of which were used in some form of "if i recall correctly".

But what about the time considerations? It should be happening further in the past shouldn't it?
And so dark matter could be mostly black holes, planets, gas etc. stuff we know and understand? But dark energy is something we completely have no idea about.

I'm not sure I understand what you are asking.

"What" is happening further in the past?


Yes. Or it could be some proportion of that stuff combined with stuff we haven't identified yet. But whatever it turns out to be, in whatever proportions, it's going to be mundane compared to the dark energy.


Yes.

Well ah, if the assumption is correct that all points in space are expanding at the same rate, then that would explain the observations that galaxies further away from us are moving faster away from us, saying nothing of any acceleration. But, the further a galaxy is from us, that astronomers abserve, are also being observed further back in time. So we are seeing that further back in time, it appears they are moving faster away from us the further they are, so would it not be correct to say that, at that time in the past, at that location in space, space was expanding at the same rate it is here on Earth, and now, at this instant?

A few clarifications for you, the time line you are interested in goes:

1. Big Bang - over in an instant, real time in real space doesn't exist before it - time elapsed during 'creation' is as close to zero as we can get.

2. Inflation - between 10 ^-35 -> 10^ -34 of a second (take a second, divide it by the age of the universe, and do it again to get a notion of the length of this interval). The geometry of spacetime overwhelms all other laws of relativistic physics (which may not have held much sway at such ultra high energy densities - here the rules or Quantum gravity under SuSy might more likely apply). So rather than gravitiational collapse (into the mother of all black holes - with event horizon 60% of the size of the known universe today) the universe instead inflates at at least 50,000 times lightspeed under our most conservative models.

3. Post inflationary expansion epoch - as things spread out temperatures cool, until the four forces seperate out (after 10 ^-34 second) and the period of relativity takes dominance in most areas of spacetime - things (quarks, leptons, energy carriers) are still moving around quickly and spacetime as the underlying field is itself expanding post haste (versus moving) so it is not necessarily relativistically bound.

4. 300,000 years after big bang - things have cooled down enough for the universe to become transparent - light can move around

5. Several million years after big bang - energy and matter in parts of spacetime gravitationally collapse to form protosuns - 100 of times bigger than a red giant - lasting for only 1 - 10 million years before going super nova and scattering elements heavier than hydrogen around the place.

Today 13.7 billion years +/- 0.2 billion years under our current models (and supported by the study of Celepheid variable stars (standard candles) for dating and distance measures.

The further we look away the faster we can see galaxies recede from us - carried predominantly by the expansion of the spacetime field - not their recession velocities within this field. We are used to seeing movement within spacetime - not spacetime itself expanding (which is not necessarily relativistically bound) - that's what kinda jerks folks thinking around.

We can see specific Type I supernovae remanents whose very specific light signature (sprectrum) is altered in a way under our model that seems to only indicates spacetimes expansion is speeding up - not slowing down.

As said in this thread - dark matter (hot or more likely cold) is just dust or exotic slow ultra heavy s-particles we haven't detected yet.

Dark energy may be different forces - those that effect the very spacetime field itself rather than the energy and matter within it. Our models of theoretical physics aren't advanced enough yet to propose a well constructed framework we can investigate - they are either too broad - string theory, allowing 10 ^ 500 different possible theoretcial relatities - or to incomplete M-theory - barely describing the edges of the mere topology of the universe let alone its governing rules.