Key ideas from Brian Greene

• The information paradox is resolved because gravitational fields outside black holes somehow 'know' what particles were consumed, preserving information through Hawking radiation
• Time machines must also be space machines - going back 30 years works because Earth returns to its orbital position, but shorter periods would leave you in empty space
• In Back to the Future, Twin Pines Mall becomes Lone Pine Mall after Marty destroys one sapling in 1955, showing attention to temporal causality details
• Black hole accretion disks heat up and expand because falling material's gravitational potential energy converts to thermal energy when it hits the disk
• Wormholes could theoretically connect to other universes in a multiverse, but different physics might make such travel lethal
• The only defense against an approaching black hole would be moving Earth itself to another star system using massive rocket propulsion