During the first months of the pandemic I occupied myself while trapped at home in making over 25 short videos explaining various interesting aspects of physics
GREAT work to share this valuable information from one of the few geniuses we still have on Earth that shares the state of the art of the cosmos..thank you..
Thank you Lawerence for this information. I was also unaware of your videos! I looked at the titles and know I will enjoy all of them. You have a knack for explaining complex subject matter to non-physicists/mathematicians in a concise and perfectly understandable way.
Thanks for the reply! I picked-up a copy of Atom from Amazon and I'm looking forward to reading about this topic and others in more detail.
Per your comment on inflation,
1) what caused the reheating since space continued to expand after inflation (though not exponentially)?
2) could the "missing" antimatter be beyond the bounds of the observable universe?
Finally, I've heard that there are asymmetric interactions that produce more matter than antimatter and vice-versa. If this is true, do you address these interactions (and/or my other two questions) in any of your books?
Sorry for all the questions but this stuff is like a critical mass of radioactive material... one question creates 2+, each of which create 2+, ... This stuff is fascinating. Makes me wish I had pursued my original desire to go into astrophysics as a kid half a century ago rather than engineering.
Cheers and thanks again for your comments and any additional references you have time to provide.
inflation stores energy in empty space.. when it ends, that energy is converted into particles and radiation.. In atom I talk at length about baryon violating interactions.
If you addressed the imbalance in the abundance of matter and antimatter, I missed it and I've been unable to find any relevant information elsewhere that answers some questions I have on that topic.
I apologize if this is the wrong forum for these questions but it seems as good as I'm going to get.
Regardinng the apparent lack of antimatter with respect to "ordinary" matter in the universe....
Consider an early, hot, dense universe with very small purturbations in the distribution of matter and antimatter. Could this universe, after inflation, result in a universe with some regions of space dominated by matter and other regions dominated by antimatter. Within one of these regions, most of the less prominant matter/antimatter would annhilate leaving only traces of the non-dominant form. Are there measurements or theory that rule out this possibility?
Can one even distinguish between matter and antimatter using astronomical observations? If not, is it possible that there is no imbalance between matter and antimatter in our universe on average and that matter and antimatter exist in approximately equal abundance? We measure little antimatter in our tiny region of the universe but what direct evidence exists that material in distant galactic clusters is also "ordinary" matter? didn't see anything in your 5 min lectures that addressed the imbalance of matter and antimatter in the universe.
Here is a short longer answer.. again I refer you to Atom, which discusses this in detail. There are strong constraints on antimatter in the universe because near the boundaries of possible antimatter regions there would be strong annihilation with matter.. in the 1970's Steigman put a very strong limit on this.. The only antimatter we see in cosmic rays from distant galaxies can be understood as being produced by the collisions of high energy particles with particles in our atmosphere. Hope this helps a bit.
BTW.. finally, inflation basically empties out the universe.. all the matter and radiation that now exists within it was produced by reheating after inflation.
It turns out Wikipedia addresses this question. They cite a NASA study looking for annihilation products in colliding superclusters. The Wikipedia page states:
"Antimatter may exist in relatively large amounts in far-away galaxies due to cosmic inflation in the primordial time of the universe. Antimatter galaxies, if they exist, are expected to have the same chemistry and absorption and emission spectra as normal-matter galaxies, and their astronomical objects would be observationally identical, making them difficult to distinguish.[32] NASA is trying to determine if such galaxies exist by looking for X-ray and gamma ray signatures of annihilation events in colliding superclusters.[33]"
I absolutely loved your five minute physics videos. Short and to the point. Although I always laughed when you talked about remembering your high school algebra. That was 50 years ago I remember nothing. But I still managed to understand the concept of what you were speaking about. Thank you very much for helping me get through the pandemic.
GREAT work to share this valuable information from one of the few geniuses we still have on Earth that shares the state of the art of the cosmos..thank you..
thanks
Thank you Lawerence for this information. I was also unaware of your videos! I looked at the titles and know I will enjoy all of them. You have a knack for explaining complex subject matter to non-physicists/mathematicians in a concise and perfectly understandable way.
Thanks for the reply! I picked-up a copy of Atom from Amazon and I'm looking forward to reading about this topic and others in more detail.
Per your comment on inflation,
1) what caused the reheating since space continued to expand after inflation (though not exponentially)?
2) could the "missing" antimatter be beyond the bounds of the observable universe?
Finally, I've heard that there are asymmetric interactions that produce more matter than antimatter and vice-versa. If this is true, do you address these interactions (and/or my other two questions) in any of your books?
Sorry for all the questions but this stuff is like a critical mass of radioactive material... one question creates 2+, each of which create 2+, ... This stuff is fascinating. Makes me wish I had pursued my original desire to go into astrophysics as a kid half a century ago rather than engineering.
Cheers and thanks again for your comments and any additional references you have time to provide.
inflation stores energy in empty space.. when it ends, that energy is converted into particles and radiation.. In atom I talk at length about baryon violating interactions.
Dr Krauss,
Thanks for the series!
If you addressed the imbalance in the abundance of matter and antimatter, I missed it and I've been unable to find any relevant information elsewhere that answers some questions I have on that topic.
I apologize if this is the wrong forum for these questions but it seems as good as I'm going to get.
Regardinng the apparent lack of antimatter with respect to "ordinary" matter in the universe....
Consider an early, hot, dense universe with very small purturbations in the distribution of matter and antimatter. Could this universe, after inflation, result in a universe with some regions of space dominated by matter and other regions dominated by antimatter. Within one of these regions, most of the less prominant matter/antimatter would annhilate leaving only traces of the non-dominant form. Are there measurements or theory that rule out this possibility?
Can one even distinguish between matter and antimatter using astronomical observations? If not, is it possible that there is no imbalance between matter and antimatter in our universe on average and that matter and antimatter exist in approximately equal abundance? We measure little antimatter in our tiny region of the universe but what direct evidence exists that material in distant galactic clusters is also "ordinary" matter? didn't see anything in your 5 min lectures that addressed the imbalance of matter and antimatter in the universe.
Here is a short longer answer.. again I refer you to Atom, which discusses this in detail. There are strong constraints on antimatter in the universe because near the boundaries of possible antimatter regions there would be strong annihilation with matter.. in the 1970's Steigman put a very strong limit on this.. The only antimatter we see in cosmic rays from distant galaxies can be understood as being produced by the collisions of high energy particles with particles in our atmosphere. Hope this helps a bit.
BTW.. finally, inflation basically empties out the universe.. all the matter and radiation that now exists within it was produced by reheating after inflation.
It turns out Wikipedia addresses this question. They cite a NASA study looking for annihilation products in colliding superclusters. The Wikipedia page states:
"Antimatter may exist in relatively large amounts in far-away galaxies due to cosmic inflation in the primordial time of the universe. Antimatter galaxies, if they exist, are expected to have the same chemistry and absorption and emission spectra as normal-matter galaxies, and their astronomical objects would be observationally identical, making them difficult to distinguish.[32] NASA is trying to determine if such galaxies exist by looking for X-ray and gamma ray signatures of annihilation events in colliding superclusters.[33]"
Traveling. Will give you an explanation later. I discuss it at length in my book Atom.
I absolutely loved your five minute physics videos. Short and to the point. Although I always laughed when you talked about remembering your high school algebra. That was 50 years ago I remember nothing. But I still managed to understand the concept of what you were speaking about. Thank you very much for helping me get through the pandemic.
thanks for watching and therefore helping encourage me to get through the pandemic too.
GREAT work and idea to share such valuable and interesting information