We would like to cordially invite you to the next Jerzy Pniewski and Leopold Infeld Colloquium of the Faculty of Physics, which will be held on Monday, June the 7th, at 4.30 PM.

Thanks to a discovery made in 1929 by Edwin Hubble, we know that the universe we live in is constantly expanding. One would expect that the rate of expansion, slowed down by gravitational interaction, would decrease with time. However, there is a surprising acceleration of this process. Moreover, there is no consensus on the rate at which the expansion occurs. Depending on the measurement method, significantly different results are obtained, which calls into question our understanding of a number of laws of physics.

These issues will be the subject of a lecture entitled "Precise determination of the cosmic distances and the Universe's expansion mysteries", delivered by prof. Grzegorz Pietrzyński from the Astronomical Observatory,  University of Warsaw.

You are welcome to join the meeting 15-30 minutes before the Colloquium to talk or chat in an informal atmosphere.

Link: https://us02web.zoom.us/j/93881687598?pwd=UmFhVUdVSXhnQ2tIVVozNmowSUNtZz09
Meeting ID: 938 8168 7598
Passcode: prv316

With best regards,

Barbara Badełek
Jan Chwedeńczuk
Jan Kalinowski
Jan Suffczyński

Abstract:

After the detection of the accelerated expansion of the Universe (Nobel prize 2011) and the introduction of an enigmatic “dark energy” component of the matter-energy content of the Universe, the physical explanation of the nature of dark energy has become a major challenge for astronomers and physicists. The recent empirical determinations of the Universe expansion based on standard candles (Cepheids, Supernovae Ia) complicated even more our understanding of the Universe since they differ by about 4σ from the value obtained from Planck data and the ΛCDM model, which suggest that new physics might be required in the models. However before one can claim the revision in modern physics all systematic errors affected the determination of the expansion rate must be very carefully investigated and accuracy, and not only precision must be reached.

In my presentation, I will discuss the most precise and accurate methods for cosmic distance determinations. I will also explain how these methods can be used to calibrate other long-range distance indicators, which allow us to calibrate Supernovae Ia. Finally, I will discuss how accurately we expect to determine the expansion rate of the Universe in the near future, and how this will impact the current discrepancy between different values of the expansion rate of the Universe as obtained with different techniques.