We will have the 15th online colloquium “Extreme Universe Colloquium” on April 13th (Thu) 22:00 (JST). The speaker is Prof. Andrew Strominger (Harvard University). For details, please refer to the poster. If you have not registered yet, please register at our online event website at least three days prior to the colloquium. (It is not necessary to register again if you have done it already.)