On Sun, Jul 20, 2025 at 1:11 AM Liz R <[email protected]> wrote: *> The earliest directly observable thing in the universe (at present) is > the microwave background. It's possible neutrinos or gravitational waves > will let us observe earlier eventa, but none of these appraoch the > inflationary era, which predates the quark-gluon plasma that became nuclei > etc.*
*If inflation existed then we should be able to detect the primordial gravitational waves it produced, although that won't be easy. In 2014 a group of astronomers thought they had done that, they thought they had observed polarization pattering in the Cosmic Microwave Background Radiation (CMBR) caused by those primordial gravitational waves, but it turned out to be caused by the magnetic field of our own galaxy. * *However the technique itself remains sound because our galaxy's magnetic field affects the polarization of different frequencies of the CMBR differently, so in principle we can cancel out the noise caused by magnetic fields and see the effect caused by primordial gravitational waves, assuming they actually exist. But to do that our measurements need to be incredibly precise. * *Our best hope for finding those primordial gravitational waves caused by inflation was the CMB-S4 microwave telescope being built at the south pole, if it had been completed then by 2030 we would know if such waves actually exist. However about two weeks ago on July 9, in an attempt to make America great again, Trump canceled CMB-S4:* *US. abandons hunt for signal of cosmic inflation* <https://www.science.org/content/article/u-s-abandons-hunt-signal-cosmic-inflation> *Trump killed CMB-S4 despite US scientists wanting it very badly, or perhaps because they wanted it, Trump doesn't like scientists very much. A 2021 survey of particle physicists said that out of all the proposed future projects CMB-S4 should be first one on the priority list. Astronomers said it should be #2 after a successor for the aging Hubble space telescope, something with a larger mirror and works at optical and near ultraviolet frequencies. Hubble was only designed to work for 15 years, but it's already been operating for nearly 29. Nevertheless I wouldn't be a bit surprised if Trump cancels Hubble's successor too.* *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* rbr -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/CAJPayv1gGJ5hw%2B3uV4hFhFiPnQ9SuzvPpqFrQjOsdMAp0_ZP1g%40mail.gmail.com.
