What are the unanswered questions in Cosmology?

[jimjohnson]

What are the greatest mysteries in Cosmology? Please comment on my list.
1 Complete explanation of black holes, what happens to time and space (worm holes?).
2 Process of symmetry breaking during initial stages of the of the big bang (includes matter/antimatter unbalance).
3 Source and characteristics of dark matter.
4 Source and characteristics of dark energy (cosmological constant).
5 Nature of gravity waves.
6 Is space and time discrete?
7 Source of ultra-high-energy cosmic rays.
8 Ultimate fate of the universe.
Any more?

 

[DennisN]

Have a look at http://math.ucr.edu/home/baez/physics/General/open_questions.html#cosmology (John Baez).

 

[skydivephil]

What happened at the big bang, was there a before and if so what?
Did inflation happen ? If so , how and is it eternal or not?

 

[jimjohnson]

Have a look at http://math.ucr.edu/home/baez/physics/General/open_questions.html#cosmology (John Baez).

Thanks, the Baez list was new to me. Jim J

 

[Mordred]

Loosely related to cosmology in Cosmological horizons though more QM related. Particle entanglement.

Thats about the only thing I could think of to the list above

 

[jimjohnson]

After reviewing the open questions in physics by John Baez, I compiled a revised list of the greatest mysteries in Cosmology. They are organized in three groups as shown below. Comments?
Big Bang/Universe
1 What happened before the big bang?
2 What was the process of symmetry breaking during initial stages of the of the big bang (includes matter/antimatter unbalance and inflation theory)?
3 Is the universe finite or infinite?
4 Are there more than 4 dimensions?
5 Is space and time discrete (arrow of time)?
6 What is the ultimate fate of the universe?
Energy/Forces
1 What is the source and characteristic of dark matter?
2 What is the source and characteristic of dark energy (cosmological constant)?
3 What is the nature of gravity waves?
Other
1 Is there a complete explanation of black holes, what happens to time and space (worm holes)?
2 What is the source of ultra-high-energy cosmic rays?
3 Why are galaxies distributed in clumps and filaments?
4 When were the first stars formed and what type were they?

 

[Ogr8bearded1]

4 When were the first stars formed and what type were they?

Fairly sure I read or saw on a programme that the first stars formed about 10 billion years ago. They were huge short lived stars composed of hydrogen. From other sources I've read, at this point only hydrogen, helium and lithium were most likely in existence with other elements being formed later from those stars deaths.

 

[Johnahh]

Fairly sure I read or saw on a programme that the first stars formed about 10 billion years ago. They were huge short lived stars composed of hydrogen. From other sources I've read, at this point only hydrogen, helium and lithium were most likely in existence with other elements being formed later from those stars deaths.

does the deep field image not show a galaxy of 13.2 billion light years away? this must mean stars formed before 10 billion years ago

 

[night_sky]

does the deep field image not show a galaxy of 13.2 billion light years away? this must mean stars formed before 10 billion years ago

There are also some stars which are measured to be older than big bang,but this doesn't make sense as we all know that big bang is the start of every thing. Either our estimation of the time of big bang must be false or the time of formation of stars must be false.

 

[Ogr8bearded1]

There are also some stars which are measured to be older than big bang,but this doesn't make sense as we all know that big bang is the start of every thing. Either our estimation of the time of big bang must be false or the time of formation of stars must be false.

They aren't older, but further away than normal expansion can explain. This is where inflation comes into play. Somehow, it appears that space became larger, for want of a better word, between our planet and a source. Space with gravitation bound entities expand slowly in their region but no longer inflate. That region can contain galaxies that are bound together as we are with Andromeda. Then there is space that doesn't have any gravitation bound entities and these areas appear to inflate instead of expand. This causes distant areas of space to recede from us, some at faster than light speed. This leads to our being able to see objects further away than the age of the Universe. The important part is that the object isn't moving away from us at great speeds, but the light from the object is having to travel further to reach us because of the inflation.

Scientists with math beyond my abilities can explain the effects that are happening. We don't know why or how though. It is believed by many that Dark Energy, which we don't know exactly what that is, plays a part. Some believe a particle called an Inflaton, which hasn't been found, could also play a role.

I'll also say my age of 10 billion was probably from old data. I did come across some recent findings of primordial gas with no heavy elements, that is from 750 million years after the Big Bang. You can read about that here http://phys.org/news/2012-12-stars-universe-million-years.html
They also mention less than 11 billion years ago heavy elements can be detected. That would suggest that some stars had formed and created heavy elements by that time.

 

[bapowell]

They aren't older, but further away than normal expansion can explain. This is where inflation comes into play. Somehow, it appears that space became larger, for want of a better word, between our planet and a source. Space with gravitation bound entities expand slowly in their region but no longer inflate. That region can contain galaxies that are bound together as we are with Andromeda. Then there is space that doesn't have any gravitation bound entities and these areas appear to inflate instead of expand.

You must be very careful with your terminology: inflation is a specific kind of expansion. Expansion occurs whenever the Hubble parameter, H=\dot{a}/a, is positive (contraction, when it is negative). Inflation is accelerated expansion, i.e. \ddot{a} > 0. Now, no expansion takes places -- inflationary or otherwise -- in gravitationally bound structures (solar systems, galaxies, etc.).

 

[Ogr8bearded1]

Thanks bapowell, I'm still trying to learn all the correct terminology. What I meant to say was that the area of a gravitation bound region could become larger. Such as, our solar system is a certain size now. If the Sun lost mass, such as it will when starts dying, the planets would orbit further away from it. Everything is still bound to each other but is now further apart and covering more area. The way I phrased it was that space in that region was slowly expanding and that was wrong.