I had a thought the other day that I would quite like feedback on:
Could the universes accelerating expansion be fuelled by the amount of mass in the universe decreasing? Is it possible that a black hole could become so massive that it tears away from/gets pinched off spacetime, how much mass...
I place two permanent magnets on a desk so that their poles are orientated for attraction. I take my hands away and they move towards each other. Where does the energy come from? Are the magnets now slightly less magnetic?
A few questions about mirrors:
1) How much light (as a percentage) does your average home mirror reflect?
2) How much light (as a percentage) does a very high quality mirror reflect?
3) How much does a very high quality mirror cost?
I’m on a train sitting next to an open window - it’s a bit stuffy - travelling towards a station. A siren is sounding at the station. As I travel toward the siren its pitch is higher that it would be if I were stood on the platform. Once I have passed the siren and I’m moving away, its pitch...