The efficacy of vaccines is estimated from trials, using statistical techniques.

Because the vaccine may not stop transmission of the virus.

Yes the approved vaccines are safe. If you balance the risks, then taking the vaccine is much safer than taking your chances with COVID-19.

On the fourteenth day of advent, we consider the night sky...which isn't actually black, but permeated by the faint afterglow of the Big Bang.

There are some interesting answers to this question, including that we live in a bubble multiverse!

On the twelfth day of advent we celebrate Stephen Hawking's contribution to cosmology.

On the eleventh day of advent we explore an unresolved puzzle concerning black holes which greatly intrigued Stephen Hawking.

Now we think we know all about black holes, here is another surprise: they are not completely black after all.