StarTalk @ NY Comic Con: It’s About Time! (Brian Greene & Neil deGrasse Tyson)

Travel Paradoxes

Neil deGrasse Tyson and Brian Greene explore the intriguing paradoxes of time travel, such as the causal loop paradox, which challenges the consistency of cause and effect. Brian explains that if time loops exist, future events could influence the past, creating logical inconsistencies. He suggests that the universe must maintain internal consistency to avoid these paradoxes 1. James Murray humorously adds that time travelers might already be among us, disguised as astrophysicists 1.

If you go to the past and you change things that prevent, for instance, your own birth, how were you there in the first place to make that change?

--- Brian Greene

The discussion also touches on the possibility of parallel universes, where changes in the past might not affect our own universe but create alternate realities 2.

   

Temporal Logic

The philosophical implications of time travel are profound, as Neil deGrasse Tyson and Brian Greene discuss the need for logical consistency in the laws of physics. Brian highlights the chronology protection conjecture, which suggests that the universe prevents changes to the past to maintain consistency 2. Neil humorously imagines sending a text message back in time to warn a friend about a banana peel, illustrating the complexities of altering past events 2.

You can't change the past of your own universe. So if you go back into the past and, say you prevent your parents from meeting, you're preventing them from meeting in a parallel copy of the universe within which you were born.

--- Brian Greene

This leads to a discussion on whether time travel, as depicted in science fiction, could ever be theoretically possible 3.

   

Doctor Who

The conversation takes a pop culture turn with references to Doctor Who, a show that has long explored time travel in a "wibbly wobbly, timey wimey" manner. Neil deGrasse Tyson notes the show's cultural impact and its portrayal of time travel through the TARDIS, a time machine that travels through space and time 4. James Murray humorously recalls the iconic blue police box, highlighting its significance in the series 5.

One of the interesting features of Doctor Who is that, this blue thingy, it's called a TARDIS, which is an acronym for Time and Relative Dimension in Space.

--- Neil deGrasse Tyson

The discussion underscores how science fiction can inspire real scientific inquiry and imagination 5.