Presenters
Adam Brown, Stanford University
Adam is a theoretical physicist at Stanford, interested in early universe cosmology, inflation, black holes, and assorted other topics. He arrived at gravitational physics via studying mathematics in Great Britain…
Q&A Takeaways:
- The story of Einstein’s overturning of Newton’s gravitational theory is a phenomenal story.
- Time machines are currently impossible – violating the null energy condition
- Black holes were a prediction resulting from general relativity, but the general idea predates Einstein.
- Gravitational waves used to be a subfield of relativity, now they have been measured.
- Our sun will never be a black hole, it’s too light.
- Gravitational theory has implications for space travel, with implications for black hole mining. One method suggested was to use the spin of a black hole for energy, but if there is no spin it still may be possible to extract energy.
- Black holes emit a lot of energy but most of it falls back into the gravitational pool. Adam is working on an inverse space elevator concept using string theory for extracting this energy.
- How do we see the afterglow of the big bang? The original big bang happened everywhere, volumetrically across the universe. Some part of that radiation is always hitting us in our current position.
- How does Adam’s work relate to humans getting into space? The reason getting off the earth is hard is due to the fundamental nature of electromagnetic forces.
- Are these black hole concepts just thought exercises or do they have real relevance? For the moment, yes they are. The engineering is still far away.
- Will we ever be able to build a warp drive? It almost certainly requires the violation of the null energy condition.
- For black hole mining, is it possible to put a laser in orbit around a black hole to harvest energy and shoot it out as light? No, orbiting the black hole at that distance is impossible. You cannot use centrifugal force to maintain orbit due to the nature of relativity.
- Would micro black holes work for something similar to this idea? Yes, one proposal is to use black holes to overcome baryon conservation mechanics and generate larger amounts of energy than nuclear reactors.
- Eventually, we need to figure out how to mine the cosmological constant itself.
Seminar summary by Aaron King.