Recent content by phoenix-anna

I'm not sure what local standard would mean?

Thanks for your detailed and focused response; it was exactly what I needed. Thanks, too, for correcting my misconception that they were Cesium clocks. This is terrific!

Putting aside the question of whether it is politically feasible, why would we do it if we could?

Physicists have proposed linking a global network of cesium clocks in a phase-coherent entangled state, for example in the article A Quantum Network of Clocks (arXiv:131045v1). My audience would like to know how better synchronization or more accurate timekeeping would lead to advances in our...

Well the hint says to consider enumerators. It is clear that the recognized language is enumerable. However, it seems we need a subset that can be enumerated in a finite number of trials. If we run the enumerator 1000 times, for example, we will see 1000 or fewer strings in the language. That is...

Summary:: Show that every infinite Turning-recognizable language has an infinite decidable subset Sipser's Theory of Computation, third edition, chapter three contains and exercise that asks us to demonstrate this. I don't know how to do this; I have certain ideas. We could modify the...

Yes, that simplifies matters. However, I am left wondering exactly what is subtracted to obtain the time interval to which the scale factor is applied. Do all the clocks have to share a common start time for computing the interval?

Yes, all clocks on the geoid should run at the same rate because they are at the same gravitational potential. I am interested in the details of how the calculation is performed: given time signals for 450 clocks running at different rates, and knowing their time dilation factors, how exactly...

The International Bureau of Weights and Measures combines the readings of 450 atomic clocks around the world to obtain a time standard with sub-nanosecond accuracy. These clocks run at different rates - a clock at 1 km of altitude gains about 7 ns a day compared to one at sea level due to the...

In a few days, I will be hosting a Zoom-based meetup in which I will be explaining the Twin Paradox (time dilatation) and the Pole-in-a-Barn paradox (Lorentz contraction). To this end, I will need to make graphics of space-time diagrams like those in Wheeler's book Spacetime Physics. Can anyone...

Trying to understand how Einstein predicted the appearance of stars during the solar eclipse around the turn of the 20th century (the first experimental confirmation of General Relativity, I believe). My impression, which is not physically correct, is that the sun attracts the photons as they...