|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
fourth "live post" from the Texas Symposium on Relativistic Astrophysics
The concluding talk on open problems in cosmology was given by Joe Silk.
I'll mention below a few things I found particularly interesting. Although the standard cosmological model essentially fits all the data, nevertheless people have looked for departures, in particular a non-constant cosmological "constant", usually parameterized as a change of equation of state with time. Observations are closing in on the regular cosmological constant, so it will probably be difficult to justify projects to narrow this down even more, in contrast, say, to gravitational-wave science, where it is clear that interesting stuff will be found. For the first time, some of the enthusiasm about gravitational waves reached me as well. Also, there is no compelling theoretical reason to expect some sort of "dark energy" other than the cosmological constant. No dark matter has been detected. Experiments for direct detection or production in colliders have turned up nothing. Possibly self-annihilation is seen in gamma rays at the centre of the Milky Way, but this is far from clear. There is still a window for WIMPs as dark matter, probably very low mass (de Broglie wavelengths measured in kiloparsecs) or high mass (TeV). Joe also thinks, though, that primordial black holes might be the best bet. The tension in the Hubble constant is real, but no-one knows what it means. If a banal explanation isn't forthcoming, perhaps new physics is around the corner. Joe also favours the low value, in part because it allows for a slightly older universe, old enough to accommodate the oldest objects. It is unclear what will resolve the inconsistencies between numerical simulations of galaxy formation and observations. While the former continue to improve to match the latter, what would be interesting are actual predictions from the former, later confirmed (or ruled out) by the latter. One of the basic questions of cosmology is still unanswered: is the universe finite or infinite? The official announcement was made for the next Texas Symposium, to be held in Prague. Some already knew, and a website (where one can register) has been up for a while. For a while, the symposia alternated betwen North America and the rest of the world. The last regular one in North America was in Vancouver in 2008, and since the 50th-anniversary symposium in Dallas in 2013, two have been in Europe and one in Africa. Maybe 2023 or 2025 will see it move back to North America. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
third "livepost" from the Texas Symposium on Relativistic Astrophysics | Phillip Helbig (undress to reply)[_2_] | Research | 0 | December 20th 19 06:46 AM |
second "livepost" from the Texas Symposium on Relativistic Astrophysics | Phillip Helbig (undress to reply)[_2_] | Research | 0 | December 18th 19 09:54 AM |
"live post" from the Texas Symposium on Relativistic Astrophysics | Phillip Helbig (undress to reply)[_2_] | Research | 0 | December 17th 19 05:47 AM |
Live Nude Astronomy - Gone "Postal"? Gone "Ballistic"? How About Going "Supernova"?! | Paine | Misc | 7 | April 6th 08 08:38 AM |
"Kali" Apology VVFWS NOMINATION: Guilty: Anyone Who Is Deliberately Supporting George Bush George Bush: World's #1 Mass Murderer "Kali" and the Torture Camps: The Abu Ghraib files Live From Fascist America | Double-A | Misc | 1 | March 26th 06 10:22 PM |