Piece of Sir Isaac Newton’s apple tree to be carried into space
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Tag Archives: physics
Video of the Galactic Center
I saw this on How The Universe Works Sunday evening. Andrea Ghez and her team have made one of the coolest science videos I have ever seen. Continue reading
The winner and still champion ….
They could have added: “Leave a good looking corpse”
Top quark motto: Live fast, die young.
To a physicist, clear results from the particle’s decay certainly look good.
Really long range thinking
Back in December I linked to The End of the Universe by John Baez, Continue reading
Found: 90% of the distant Universe
From Bad Astronomy
Happy Pi Day and Happy Einstein’s Birthday!
Happy Birthday!
Background and significance at How stuff works. See also Top quark chefs and Wikipedia.
No laptops in this class!
In general relativity…
Einstein tells us that space and time are dynamical, and in particular that they can evolve with time. When the space through which particles move is changing, the total energy of those particles is not conserved.
Don’t look for a free lunch. There are still rules:
….energy and momentum evolve in a precisely specified way in response to the behavior of spacetime around them. If that spacetime is standing completely still, the total energy is constant; if it’s evolving, the energy changes in a completely unambiguous way.
This has been known since the 1920’s, and I learned about it when I first seriously studied GR at Stanford in 1973. However, scientists now need to pay more attention to it. In recent decades astronomical observations have have revealed many more situations where the effects of general relativity are significant.
Mathematical details at Is Energy Conserved in General Relativity?
From Hilbert Space to Dilbert Space, and beyond 