There's only three known forces, distinct forces in the universe. Two of them actually in the 1970s were merged into one. electromagnetism and the weak nuclear force are manifestations of the same force. If you go back into high temperature, high density, two of those forces come together and they become one.
The pull of gravity (the force, not the movie) is irresistible as Neil deGrasse Tyson and Leighann Lord grapple with weighty fan questions about matter and the curvature of spacetime.
Read more and listen to the full episode at http://www.startalkradio.net/show/cosmic-queries-gravity/
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