Ask Ethan: Would Traveling Back In Time Destroy The Universe?
“My 8 year old watched the Back to the Future movies for the first time and would like to know if, as Doc Brown suggests, the creation of a temporal paradox could unravel the space-time continuum and destroy the entire universe?”
Whenever someone attempts to travel back in time in any science-fiction setting, they’re always warned against messing with the timeline and making drastic changes. The reason? If you alter the past, you have a chance of changing the present in some dramatic ways, potentially in ways that would even prevent your own existence, or the possibility of events that have already occurred. But that’s normally the entire motivation for traveling back in time, from 12 Monkeys to Terminator to Back to the Future. Yet there might be not just one, but two possible ways out. Traveling back in time and changing the past may or may not be physically possible, but if it is, it might lead to a new present that’s just fine in terms of the Universe’s stability, no matter what it is you do.
What are the problems, and potential solutions, to traveling back in time and altering the past? Find out today!
Ask Ethan: Which Movies Get The Science Of Time Travel Right?
“I’m admittedly a fan of time-travel movies (however they explain it). What movie makes the best case for using this plot device accurately?”
Time travel has been a staple of fiction for centuries, as the notion of either traveling forward in time to explore the future or back in time to right a past wrong have been a part of humanity’s imaginings for perhaps always. But we have explicit laws and rules for traveling through time, and how our motion through space affects it. In General Relativity, the possibilities of wormholes and closed-timelike-curves arises, opening up a whole new set of avenues for success. From Bill & Ted’s excellent adventure to Idiocracy, from Harry Potter and the Prisoner of Azkaban to Interstellar, and from Back to the Future to Groundhog Day, the science of time travel is one of the most fascinating ones out there.
Which movies get it right, and which ones get it egregiously wrong? Find out what my evaluations are on this edition of Ask Ethan!
‘Star Trek: Discovery’ Confronts The Ethics And Science Of Survival, And Human Frailty
"Finally, Burnham is forced to confront her failings as a human being throughout the series. Her repeated treachery. Her inability to tell the truth to Saru. Her decision to save the Emperor because of her own regrets. Her lack of internal strength to see Tyler, and then her failure to own up to her continued love for him. Everyone sees her weakness: Saru, Georgiou, Tilly, Tyler. Yet all she can do is make excuses. The first rule of ethics is you must be honest with yourself about yourself, and until Burnham can do that — something she’s been unable to do all series long, particularly since the Battle of the Binary Stars — her character growth will be fundamentally limited, even as everyone else around her blossoms.“
There’s so much to discuss from the latest episode of Star Trek: from the plot itself to the ethical decisions and dilemmas to the science. In particular, this episode focuses on the science of time travel, nature vs. nurture, and terraforming. While we may think of so much of it as complicated, the aspects these three take on are as straightforward as they come. There are the consequences of jumping just a little bit ahead into the future, and the catastrophic changes that can happen in a short time. There is the (flawed) idea that we would be the exact same person, with the same moral compass, regardless of how we were raised, an assumption that Discovery very clearly challenges with the mirror Universe. And there’s the fascinating idea that all it would take was one hardy, well-adapted species to turn a planet from lifeless into thriving. That may, in fact, be all it takes to give life on an uninhabited world its start.
Come check out the latest recap, review, science, and right-and-wrong from Star Trek: Discovery. We’re just one episode from the season finale!
How Traveling Back In Time Could Really, Physically Be Possible
“Satisfyingly, we discover that this form of time travel also forbids the grandfather paradox! Even if the wormhole were created before your parents were conceived, there’s no way for you to exist at the other end of the wormhole early enough to go back and find your grandfather prior to that critical moment. The best you can do is to put your newborn father and mother on a ship to catch the other end of the wormhole, have them live, age, conceive you, and then send yourself back through the wormhole. You’ll be able to meet your grandfather when he’s still very young — perhaps even younger than you are now — but it will still, by necessity, occur at a moment in time after your parents were born.”
So, you want to travel back in time? It’s long been considered as a trope in science fiction movies, television, and literature, but the laws of physics make traveling backwards through time very difficult. In special relativity, it’s impossible, as you can only control the rate you move forward through time; the direction is non-negotiable. But in General Relativity, the curvature of space and time opens up additional possibilities. You can create a stable, traversible wormhole if some type of negative mass/energy exists, with a supermassive black hole connected to its negative mass/energy counterpart. Now, move one end of that wormhole close to the speed of light, and the two mouths age at different rates. Travel through the fast-moving end, and discover you’re back at the stationary end way in the distant past… but still in the future compared to when the wormhole was created.
It’s a brilliant way to achieve time travel, and as a bonus, it makes it impossible to go back in time and kill your own grandfather before you were conceived! Come learn how time travel could really, physically be possible after all.
Ask Ethan: What Science Experiments Will Open The Door To The Future?
“Provided that we have some luck, what science experiments that are going to happen withing a couple of decades could open us a way to build some sci-fi movie tech?”
The dream of futuristic technologies and what they might enable us to do – travel back in time, create artificial gravity, traverse the stars, create unlimited energy – are some of the best goals science can aspire to. While a great many of the technologies we’ve envisioned might well prove to be physically impossible, these four could immediately become reality if just one experiment, potentially within the next decade, reveals a surprise it should be able to detect. If dark matter is detected and proves to be its own antiparticle, then all we need to do is figure out how to harness it and unlimited fuel along an interstellar journey is ours for the taking. Antimatter might fall upwards in a gravitational field, having a negative mass, which would create artificial gravity and even, potentially, warp drive. And if the Universe rotates with just the right value, traveling back in time might become a part of science, not just science fiction.
There are experiments ongoing today and ones presently under design that might unlock these mysteries and more. Find out all about them on this week’s Ask Ethan!
New Podcast: Is Time Travel Possible?
Is time travel possible? Of course it’s inevitable in some sense, as we always move through the Universe at the “boring” rate of one second per second. But what about traveling into the future? If we go, can we ever come back? And what about back in time? Would it be possible to alter the past, or revisit a historical event as an observer?
The mathematics of relativity opens the door to a lot of possibilities, but the physical Universe has a lot to say about it, too. Find out on the latest edition of the Starts With A Bang podcast!
Is Time Travel Possible, According To Science?
“You can witness the evolution and destruction of humanity; the end of the Earth and Sun; the dissociation of our galaxy; the heat death of the Universe itself. So long as you have enough power in your space ship, you can travel as far into the future as you like.”
Have you ever wondered about time travel? Perhaps you have your destination in the far future, and want to see how it all turns out? Maybe you want to return to the past, and alter the future or present by your actions there? Or maybe you want to freeze time altogether? If you want to know whether it’s possible, the physics of relativity holds the answer. Special relativity allows us to control our motion through time by manipulating our motion through space. The more we move through space, the less we move through time, allowing us to travel as far as we want into the future, limited only by our energy available for space travel. But going to the past requires some specific solutions to general relativity, which may (or may not) describe our physical Universe.
What’s the status of traveling through time? Come get the scientific story (with a brand new podcast) today!