Speaker 1: Get in touch with technology with tech Stuff from how
Speaker 1: stuff works dot com. Hey there, and welcome to tech Stuff.
Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with
Speaker 1: How Stuff Works, and iHeart radio and I love all
Speaker 1: things tech. And today we're gonna talk about a fun
Speaker 1: science fiction e kind of topic. We're gonna talk about
Speaker 1: time travel. But I don't really want to focus too
Speaker 1: much on the various proposed technological approaches to time travel,
Speaker 1: because those are all either pure science fiction or they're
Speaker 1: very much hypothetical and based upon lots of of tenuous guesswork. Instead,
Speaker 1: I'm gonna do something even more outlandish, like how could
Speaker 1: we tell if time travelers have walked among us? All Right,
Speaker 1: so we're gonna talk a little bit about that. I
Speaker 1: will cover a bit of the philosophy behind time travel,
Speaker 1: because there's still a debate about whether or not time
Speaker 1: travel is a technological possibility. I mean, we know that
Speaker 1: time travel works, because we're doing it right now, traveling
Speaker 1: forward in time at the rate of sixty minutes per hour.
Speaker 1: That that's just how time works. However, we also know
Speaker 1: that if you were able to say, get in a
Speaker 1: spaceship and push that spaceship too incredible speeds that humans
Speaker 1: have never been able to get to. But let's say
Speaker 1: that you're getting into a spaceship and you're able to
Speaker 1: accelerate to near the speed of light, like five the
Speaker 1: speed of light. That is wicked fast. And you know,
Speaker 1: we know the speed of light is the speed limit
Speaker 1: for space time in our universe, so you're not gonna
Speaker 1: go faster than that. And you can't really get mass
Speaker 1: to the speed of the speed of light as it
Speaker 1: has mass. That that's one of the limiting factors. But
Speaker 1: let's say you can get If you were able to
Speaker 1: do that, then time to you would seem to pass
Speaker 1: as normal, like a second would be a second, a
Speaker 1: minute would be a minute. It would feel exactly the
Speaker 1: same as if you were anywhere else. However, time with
Speaker 1: respect to someone who's back on Earth, it would seem
Speaker 1: to be very different. It would seem as if the
Speaker 1: people back on Earth were living out time at a
Speaker 1: much accelerated rate, and that to them, you are experiencing
Speaker 1: time at a much slower rate. So let's say you
Speaker 1: go off on a five year adventure of exploration around
Speaker 1: the galaxy. So you're zooming around at the speed of light.
Speaker 1: After five years, you come back home to Earth, it
Speaker 1: would look like everyone had aged decades while you were
Speaker 1: gone for just five years. Like you aged five years,
Speaker 1: everyone else aged fifty years. Everyone else looks much older
Speaker 1: to them. It would seem as if time had barely
Speaker 1: touched you at all. They had lived out their lives
Speaker 1: decade after decade, and you are barely any older than
Speaker 1: when you left. So, in a way, that's kind of
Speaker 1: like time travel, right it would be like you are
Speaker 1: traveling to the future, but you're doing so in a
Speaker 1: way that time is still to you, passing exactly the
Speaker 1: way it always has. It's only when you take the
Speaker 1: reference of someone else. Uh, this is why we call
Speaker 1: it special relativity. That's part of the theory of special relativity.
Speaker 1: It's relative to the perspective of someone else who's moving
Speaker 1: at a different speed throughout space time. So that kind
Speaker 1: of time travel would be totally possible if you could
Speaker 1: get a spacecraft up to those speeds, which right now
Speaker 1: would be impossible for us. But if you could, you
Speaker 1: would be able to travel to the future. But what
Speaker 1: if you wanted to travel to the asked ah That
Speaker 1: would be super duper hard traveling to the future is easy,
Speaker 1: you just wait. Traveling to the past way more tricky. So, scientifically,
Speaker 1: based upon what we understand of our universe and the
Speaker 1: laws of physics as we understand them right now, we
Speaker 1: would say that if time travel to the past is
Speaker 1: possible at all, it's probably only possible up to the
Speaker 1: point where uh are from the point where the time
Speaker 1: travel machine was first made. So, in other words, let's
Speaker 1: say it's Tuesday afternoon and you don't have anything going on,
Speaker 1: so you build yourself a time machine. Well, any point
Speaker 1: after Tuesday afternoon, you could use that time machine to
Speaker 1: travel back to Tuesday afternoon, but you couldn't go to
Speaker 1: Tuesday morning or Monday, or any point before you had
Speaker 1: created the time machine. The time machine would be your
Speaker 1: point zero. So, sadly, this would mean there's no way
Speaker 1: for us to go back to the time of the
Speaker 1: dinosaurs unless we just happened to come across some t
Speaker 1: rex's old time machine sitting around somewhere or something, or
Speaker 1: maybe an alien time machine where aliens had visited the
Speaker 1: Earth millions of years ago, and so we find their
Speaker 1: time machine. It's still miraculously works. We figured out how
Speaker 1: to use it, and it doesn't turn us into goo.
Speaker 1: That's a lot of ifs. Also, it depends upon aliens
Speaker 1: having visiting us, so a long shot at best, I
Speaker 1: guess we could say, however, we can look for evidence
Speaker 1: to see if time travelers have visited us. So let's
Speaker 1: say that someone has infened a time machine at some point.
Speaker 1: Presumably that would mean someone from the future could come
Speaker 1: back to some point in our past up to present day,
Speaker 1: any point where the time machine had been made forward,
Speaker 1: and we would potentially be able to figure that out.
Speaker 1: How would we do that? How do we identify the
Speaker 1: time travelers who secretly walk among us? Well, maybe they
Speaker 1: would identify themselves. So the first person I want to
Speaker 1: talk about is someone that I actually did a full
Speaker 1: episode of tech stuff about years and years ago. This
Speaker 1: would be John t toor or tight towards t I
Speaker 1: t O R. This is one of those Internet memes
Speaker 1: from the early early days of the Internet, back in
Speaker 1: the late nineties early two thousands, was actually a radio
Speaker 1: thing before it was an Internet thing. And the story
Speaker 1: is that, supposedly, according to the narrative, a guy living
Speaker 1: in the year twenty six travels back in time, and
Speaker 1: the purpose for traveling back in time. According to the guy,
Speaker 1: was that he needed to get a specific compute, one
Speaker 1: of the early portable computers. And by portable, I mean
Speaker 1: you could in theory lug it around, but it was
Speaker 1: super heavy, like many many, many pounds. It was a
Speaker 1: nineteen computer, the IBM fifty. I think it was like
Speaker 1: fifty pounds if I'm not mistaken in weight, not in
Speaker 1: not in cost. And that, uh, this computer somehow was
Speaker 1: going to be able to fix a problem that existed
Speaker 1: in his present day of twenty thirty six, that problem
Speaker 1: being largely this issue of a Y two K like problem.
Speaker 1: So if you remember the Y two K issue, it
Speaker 1: was that a lot of computer programming had designated years
Speaker 1: as being two digit numbers. Because this was back in
Speaker 1: the nineteen hundreds, the late nineteen hundreds, when no one
Speaker 1: was really thinking, oh, the system I build now is
Speaker 1: going to be the same one we're gonna rely on
Speaker 1: thirty years from now. So pro members were building in
Speaker 1: the shortcut of of you know, abbreviating the year to
Speaker 1: two digits. The game. By the time this is getting
Speaker 1: to the point where we're at nine, surely will have
Speaker 1: moved on to a different architecture. Software architecture, and they
Speaker 1: were wrong, because if we can build onto existing structures
Speaker 1: without having to redo the whole thing, that's usually the
Speaker 1: choice we make. So the Y two K problem was
Speaker 1: that no one was really sure what would happen when
Speaker 1: the year rolled over from to two thousand and all
Speaker 1: those two digit numbers would now say zero zero instead
Speaker 1: of nine nine. Would that mean that the systems would
Speaker 1: suddenly think that we had rolled over and now the
Speaker 1: year was nineteen hundred and a lot of those systems
Speaker 1: were important for things like calculating things like interest and uh,
Speaker 1: you know, financial issues, and other control systems. There's a
Speaker 1: worry that things were really going to go pear shaped
Speaker 1: on January one, two thousand, when all these computer systems
Speaker 1: might spontaneously fail, and so there's a huge effort made
Speaker 1: to fix that. Well, there's a similar issue in Unix,
Speaker 1: except instead of it being the year two thousand, it
Speaker 1: would be the year twenty thirty eight. And so John Titor,
Speaker 1: as he called himself, said that was why he came
Speaker 1: back in time, was to get hold of this particular
Speaker 1: computer in order to solve this problem in the future
Speaker 1: and head off a terrible calamity of all the computer
Speaker 1: systems in in the world failing in various ways. The
Speaker 1: very first appearance of this personality was in a facts
Speaker 1: that used to be a thing still is in a
Speaker 1: few rare cases, but the facts that was sent to
Speaker 1: Art Bell, who was the host of a show called
Speaker 1: Coast to Coast a m which was really a show
Speaker 1: that focused on all sorts of weird fringe theories and
Speaker 1: paranormal phenomenon and things like that. This is back in
Speaker 1: nineteen and in that message, the person claimed that the
Speaker 1: Y two K problem had created a huge catastrophe in
Speaker 1: the future. And so there were a lot of warnings
Speaker 1: that John Titor would give. Over the course of the
Speaker 1: next several years. He would show up on various message
Speaker 1: boards giving various details about the future according to his travels.
Speaker 1: You know, he's making all these these claims that were unsubstantiated,
Speaker 1: although if you wait around long enough you could find
Speaker 1: out if they were true. But a lot of his
Speaker 1: predictions failed failed to play out the way he had said.
Speaker 1: Like he said, why two K was gonna lead to
Speaker 1: massive disaster? It didn't. It did cause problems, but nothing
Speaker 1: nearly on the level that what of what people were
Speaker 1: afraid of? He said the two thousand four Olympics would
Speaker 1: get canceled. They didn't. He also said that by the
Speaker 1: United States would split into warring factions and there'd be
Speaker 1: a great civil war, which did not happen. I mean,
Speaker 1: you could say that people are more polarized than ever before,
Speaker 1: but we haven't turned into tribal groups that are actually
Speaker 1: making war on each other in uh, in the way
Speaker 1: that he was suggesting. And he did say, however, that
Speaker 1: he was really from a parallel universe, one that was
Speaker 1: nearly identical to ours, but that there was probably a
Speaker 1: deviation between one to two per cent, so that things
Speaker 1: that happened in his universe may not happen exactly the
Speaker 1: same way in ours, but largely things would be more
Speaker 1: or less the same. He also said eventually that the
Speaker 1: future wasn't necessarily fixed, which is another get out of
Speaker 1: jail free car card if you're a time traveler. I
Speaker 1: guess uh. Eventually, there was some evidence that suggested that
Speaker 1: this was all the work of a couple of brothers
Speaker 1: in Florida who had sort of orchestrated the whole thing.
Speaker 1: There was another person who claimed that he was sort
Speaker 1: of consulted as part of this and that was kind
Speaker 1: of a collaborative storytelling exercise that sort of snowballed out
Speaker 1: of control. So chances are not a real time traveler.
Speaker 1: So then there was also the sad but fascinating tale
Speaker 1: of a man who used the pseudonym Bob White among others.
Speaker 1: This was back in the early two thousand's and this
Speaker 1: guy sent out emails in huge blasts, like millions of
Speaker 1: people were getting these emails, and essentially this was a
Speaker 1: spam email, but instead of trying to sell something, uh,
Speaker 1: this spam email was asking for some pretty crazy fictional technology.
Speaker 1: It was like a three page long manifesto and it
Speaker 1: included things saying that the person needed something like an
Speaker 1: AcBe five by twenty four series time transducing capacitor was
Speaker 1: built in temporal displacement, which is not a thing, but
Speaker 1: was asked for. So a guy named Dave Hill responded
Speaker 1: to this. He found it fascinating and he went so
Speaker 1: far as to even send an old hard drive, calling
Speaker 1: it a warp generator. But then he found out that
Speaker 1: the recipient wasn't just someone like making a joke on
Speaker 1: the internet. It was someone who actually seemed to truly
Speaker 1: believe in what they were saying, and they were showing
Speaker 1: some signs of paranoia and some other concerns. And it
Speaker 1: turned out that this was Robert Robbie Todino, who had
Speaker 1: been sending millions of emails since November two thousand one.
Speaker 1: He was in his twenties. He had founded a company
Speaker 1: called RT Marketing, which sent out spam messages about all
Speaker 1: sorts of products on behalf of various clients. But he
Speaker 1: was eventually hit with a five thousand dollar fine from
Speaker 1: the state of Massachusetts in a cease and desist order
Speaker 1: for that sort of stuff. That's around the time when
Speaker 1: he started sending out these anonymous calls for help in
Speaker 1: obtaining various science e sounding but largely fictional pieces of equipment.
Speaker 1: And he said that his life had been quote severely
Speaker 1: tampered with end quote and they needed to find a
Speaker 1: way to rewind time to fix it. And he called
Speaker 1: himself Bob Wyatt or Tim Jones or several other aliases
Speaker 1: as he corresponded with other people. His father said that
Speaker 1: Tudino had mental health problems, including dissociative disorder, and that
Speaker 1: the interactions with people had made it worse. Some people
Speaker 1: were likely taking advantage of him it's a very sad story.
Speaker 1: But he was seemingly convinced that time travelers were in
Speaker 1: fact real and walking among us, but no actual evidence
Speaker 1: came from that. So that's one way we can look
Speaker 1: for time travelers, look for people who claimed to be them.
Speaker 1: But maybe that won't work. Maybe people are maybe they're
Speaker 1: a little more shy. So what if we were to
Speaker 1: ask them to show up at a particular place in time.
Speaker 1: So that was the thought behind the m i T
Speaker 1: Time Traveler Convention. On May seven, two thousand five, students
Speaker 1: at m i T, who were led by an Electrical
Speaker 1: engineering and Computer scien it's graduate student named Amal Dora
Speaker 1: I held an official convention for time travelers and according
Speaker 1: to Dora, any real lifetime traveler was welcome to show
Speaker 1: up with no rs VP. They just had to bring
Speaker 1: proof that he or she was from the future. And
Speaker 1: and what I think was a pretty clever move. They
Speaker 1: focused very heavily on getting the word out to the press.
Speaker 1: And this wasn't just about night marketing a goofy silly event.
Speaker 1: It was a vital part of this experiment because by
Speaker 1: publicizing the event, by spreading the word wide, they could
Speaker 1: better ensure that people time travelers in the future learn
Speaker 1: about that convention, that party, and that as a result,
Speaker 1: they could travel back to that moment in time to
Speaker 1: attend the party. And as they said, this web page
Speaker 1: is insufficient. In less than a year, it will be
Speaker 1: taken down when I graduate. Spoiler alert, it wasn't taken down.
Speaker 1: It's still up. And furthermore, the World Wide Web is
Speaker 1: unlikely to remain in its present form permanently. Probably true,
Speaker 1: but it's still pretty much the way it was back then.
Speaker 1: We need volunteers to publish the details of the convention
Speaker 1: in enduring forms so that the time travelers of future
Speaker 1: millennia will be aware of the convention. This convention can
Speaker 1: never be forgotten. We need publicity in major outlets, not
Speaker 1: just Internet news. Think New York Times, Washington Post, books,
Speaker 1: that sort of thing. If you have any strings, please
Speaker 1: pull them. And you could ask, well, what what can
Speaker 1: I do? And they said that's great. Uh, write it
Speaker 1: down on a piece of acid free paper and slip
Speaker 1: those pieces of paper into obscure books in academic libraries,
Speaker 1: carve them into a clay tablet. If you write for
Speaker 1: a newspaper, insert a few details about the convention, tell
Speaker 1: your friends so that the word of the convention will
Speaker 1: be preserved in our oral history. Time travel is a
Speaker 1: hard problem and it may not be invented until long
Speaker 1: after m I t itself has faded into oblivion. Thus
Speaker 1: we ask you to include the latitude longitude information when
Speaker 1: you publicize the convention. You can also make an absolute
Speaker 1: commitment to publicize the convention afterwards. In that case, bring
Speaker 1: a time counsel or whatever it may be to the party,
Speaker 1: and then bury it afterwards. So I got a lot
Speaker 1: of coverage. They even got our rite up in Nature
Speaker 1: News that was called Time Travelers Snub Conference, So I
Speaker 1: guess you can see how that turned out. The website,
Speaker 1: which like I said, is still up to this day,
Speaker 1: says update. The convention was a mixed success. Unfortunately we
Speaker 1: had no confirmed time travelers visit us, yet many time
Speaker 1: travelers could have attended incognito to avoid endless questions about
Speaker 1: the future. We had a great series of lectures, awesome bands,
Speaker 1: and even a DeLorean. We regret having had to turn
Speaker 1: away visitors, but there was were capacity restrictions governing Morse Hall.
Speaker 1: Thanks so much to the dozens of people who helped,
Speaker 1: I've got a lot more to talk about trying to
Speaker 1: track down those pesky time travelers, but first let's take
Speaker 1: a little time out to thank our sponsor sticking with
Speaker 1: these events that are being held for time travelers. On
Speaker 1: June two thousand nine, Stephen Hawking held a party in
Speaker 1: Cambridge for time travelers. All time travelers were invited to come,
Speaker 1: but the catch was he did not issue the invitation
Speaker 1: to the party until after the party had already taken place.
Speaker 1: So the invitation flyer read you are cordially invited to
Speaker 1: a reception for time Travelers hosted by Professor Stephen Hawking,
Speaker 1: to be held at the University of Cambridge, Gonville and
Speaker 1: Caius College, Trinity Street, Cambridge. And then it's gave the
Speaker 1: exact global positioning coordinates for the party and said champagne
Speaker 1: would be served. But I guess it wasn't that rally
Speaker 1: party because it was it was held at noon, unless
Speaker 1: I don't know, kay, Cambridge, if you're out there, do
Speaker 1: you get turned up at noon? If so? Well done? Anyway,
Speaker 1: Later on, after the party had happened, he publicized the
Speaker 1: party in the press and on the web, and had
Speaker 1: an elegantly designed version of this flyer printed up and
Speaker 1: placed on sale, and said I'm hoping copies of it,
Speaker 1: in one form or another, will survive for many thousands
Speaker 1: of years. Maybe one day someone living in the future
Speaker 1: will find this information and use a wormhole time machine
Speaker 1: to come back to my party, proving that time travel
Speaker 1: will one day be possible. But no one showed up.
Speaker 1: Hawking later said during an interview at the two thousand
Speaker 1: twelve Seattle Science Festival, I have experimental evidence that time
Speaker 1: travel is not possible. I gave a party for time travelers,
Speaker 1: but I didn't send out the invitations until after the party.
Speaker 1: I sat there a long time, but no one came.
Speaker 1: So I guess Stephen Hawking just kind of watched champagne
Speaker 1: slowly go flat. So if they're not showing up to
Speaker 1: our parties, maybe maybe there's some you know, weird laws
Speaker 1: in the future about time travel and keeping it secret.
Speaker 1: What if we were to use big data to mind
Speaker 1: for the presence of time travelers. There is a paper
Speaker 1: that was written back in or released in It was
Speaker 1: written before that, titled searching the Internet for Evidence of
Speaker 1: Time Travelers. It was written by Robert J. Nemerov and
Speaker 1: Theresa Wilson over at the Michigan Technological University's physics department,
Speaker 1: and they looked for evidence of time travelers by sifting
Speaker 1: through enormous amounts of data on the Internet. And the
Speaker 1: idea was that if travelers from the future were to
Speaker 1: come to the Internet age, they might not, you know,
Speaker 1: come forward and proclaim themselves as time travelers, but they
Speaker 1: might leave some sort of race of their presence on
Speaker 1: the web if you just looked for things that showed
Speaker 1: evidence of what they called prescient knowledge, in other words,
Speaker 1: looking for any indications that someone knows about something before
Speaker 1: that something actually happens. And they used three main methods
Speaker 1: to do this. First, they looked back at the web
Speaker 1: for terms that would not have made any sense at
Speaker 1: the time they were published, but which now referred to
Speaker 1: something meaningful. They gave examples. They said, search terms related
Speaker 1: to comment I sn I S O N, which was
Speaker 1: not discovered until September twenty first, two thousand twelve. Or
Speaker 1: Pope Francis, which was formerly Cardinal Jorge Mario Burgoglio uh.
Speaker 1: He chose the name Francis in March two thousand thirteen,
Speaker 1: but before March two thirteen there was no Pope Francis.
Speaker 1: There never been a Pope Francis, he's the first one.
Speaker 1: So if they said we find evidence of these terms
Speaker 1: existing before those dates, that could indicate a time traveler
Speaker 1: who was googling around or maybe popping on Facebook or
Speaker 1: Twitter or something and looking for these terms, but it
Speaker 1: was before those things had happened. The next method they
Speaker 1: used was they looked for prescient search terms in search
Speaker 1: engine history. So again, if let's say that they're not
Speaker 1: posting to Facebook or Twitter or whatever. Also, Facebook is
Speaker 1: problematic because you could back date posts for a really
Speaker 1: long time, so you could actually cheat. You could post
Speaker 1: about you could set the date on a post to
Speaker 1: being before the thing actually happened, so that would be
Speaker 1: it would look like you were a time traveler, but
Speaker 1: it was just because Facebook allowed you to do it. Anyway,
Speaker 1: they said, let's see if there's any evidence of search
Speaker 1: terms being used before these things happened. Google trends didn't
Speaker 1: really turn up any interesting results. But then they pointed
Speaker 1: out Google aggregates this data and it very well. Maybe
Speaker 1: that if it's a time traveler who's come back to
Speaker 1: present day, there might not be enough information there for
Speaker 1: you to draw an in conclusions. Uh, one of the
Speaker 1: studies authors happened to have access to the back end
Speaker 1: for NASA's Astronomy Picture of the Day subsite, so he
Speaker 1: checked to see if anyone had searched for any evidence
Speaker 1: of common ice and before it had been discovered. And Third,
Speaker 1: they invited the future people to travel into the past
Speaker 1: before the end of August tweet at them with one
Speaker 1: of two hashtags. They said, if you're a time traveler,
Speaker 1: go back to the past. Use Twitter and send on
Speaker 1: the message and include one of these two hashtags. Either
Speaker 1: hashtag I can change the past. Two. That would be
Speaker 1: if the time travelers says yes, I can travel through
Speaker 1: time and history is plastic, which means the past is changeable.
Speaker 1: You can go back in time and change things, and
Speaker 1: the present and the future are not set in stone.
Speaker 1: The second was hashtag I cannot change the past two,
Speaker 1: and that would be if time travel works, but it
Speaker 1: works in a fixed history scenario, which means it's possible.
Speaker 1: But the stuff that we experience is already part of
Speaker 1: the whole time travel thing. Like you, you wouldn't be
Speaker 1: able to change the future. It would have to be
Speaker 1: stuff that it's the way it's always happened. It's a
Speaker 1: little confusing. It actually goes into a principle called self consistency.
Speaker 1: They were careful to not use the hashtag in search
Speaker 1: until after their advertisement asking for past tweets in order
Speaker 1: to prevent time paradoxes, and it didn't turn up any results.
Speaker 1: So in the end they discovered no prescient knowledge through
Speaker 1: any of these inquiries. So that leads to the question
Speaker 1: of if time travel is possible, why haven't we seen
Speaker 1: any evidence of it. So, so possibility number one is
Speaker 1: time travel to the past is impossible. It's just not
Speaker 1: possible at all, at least not for human beings, or
Speaker 1: we never figure out how to do it. The next
Speaker 1: is that, yes, time travel is possible, but we have
Speaker 1: that limit of you can only go back as far
Speaker 1: as a time travel machine has been invented, and so
Speaker 1: far no one's invented one. That's the next possibility. Then
Speaker 1: there's the concept of causality branching, or the multiple world's theory,
Speaker 1: the idea that that our timeline is one of many,
Speaker 1: and anytime you travel through back through time, you're actually
Speaker 1: creating a split from your timeline. So you have your
Speaker 1: original timeline where everything is the same and nothing in
Speaker 1: the past gets changed. Then you have the new timeline
Speaker 1: that splits off to the moment when you travel back
Speaker 1: to it, and so you can make changes to that,
Speaker 1: and everything in that timeline is affected by your actions.
Speaker 1: But your original timeline, the one you traveled from, continues
Speaker 1: to go without you in it because you've you've moved
Speaker 1: away from it, but it doesn't the past events don't
Speaker 1: get changed round, so you're looking at lots of parallel universes.
Speaker 1: So this would allow you to do stuff like actually
Speaker 1: go back in time and to kill yourself or your father,
Speaker 1: or your grandfather or or any of your ancestors. And
Speaker 1: it wouldn't affect you, the person who traveled back, because
Speaker 1: you're from a parallel timeline, But it would mean that
Speaker 1: the alternate version of you would either die or never
Speaker 1: be born because you eliminated them and called blood you,
Speaker 1: you crazy person. So the other possibility is that maybe
Speaker 1: time travelers from the future are just hiding from us
Speaker 1: and are just really really good at it. Uh So
Speaker 1: that's also a question of how would that be possible.
Speaker 1: I mean, people make mistakes all the time, so you
Speaker 1: would think someone somewhere would have slipped up if they
Speaker 1: had traveled back in time. There's gotta be some goofs, right,
Speaker 1: if time travel is possible, some goofs eventually gets hold
Speaker 1: of time travel and makes a complete mess of things.
Speaker 1: But we haven't really noticed that. I'm gonna put political
Speaker 1: commentary aside. Let me take another quick break, and then
Speaker 1: we'll conclude our discussion about searching for time travelers. All right,
Speaker 1: So we talked to a little bit about the different
Speaker 1: ways that we might be able to to find time travelers.
Speaker 1: There are a couple of other things I think would
Speaker 1: be kind of fun to talk about, like, uh, evidence
Speaker 1: supposedly of time travel. You may have heard about Chaplain's
Speaker 1: film about the Circus, and there's a image of a
Speaker 1: woman in the background. Um, it's this movie was made
Speaker 1: in nineteen and there's a woman in the background who
Speaker 1: looks like she's on a smartphone, Like it looks like
Speaker 1: she's holding a smartphone to her face, and you're thinking, nine,
Speaker 1: this is someone from the future, but so far in
Speaker 1: the future that smartphones are no longer a thing. Although
Speaker 1: it raises interesting questions like what network would that smartphone
Speaker 1: be on if you had traveled back to nineteen eight.
Speaker 1: There's no infrastructure there to support it. It turns out
Speaker 1: it probably was just a very large hearing aid, because
Speaker 1: hearing aids of that sort of size, portable hearing aids
Speaker 1: that you could carry around, but they were quite large,
Speaker 1: had been around for a few years. Uh. Prototypes have
Speaker 1: been around for at least a couple of years. One
Speaker 1: had been patented as early as nineteen twenty four, so
Speaker 1: night was still pretty early for that. They might probably
Speaker 1: were pretty rare, but it seems like a more accurate
Speaker 1: guests than a woman had time traveled to be an
Speaker 1: extra and a Charlie Chaplin film. Uh. There's also the
Speaker 1: famous picture of a group of people standing around looking
Speaker 1: at a bridge and one of them looks like a
Speaker 1: hipster from modern day, wearing like a it looks like
Speaker 1: a print T shirt, and them crazy looking sunglasses. And
Speaker 1: the picture was taken in ninety one at South Fork
Speaker 1: Bridge in gold Bridge, British Columbia. However, upon closer examinations,
Speaker 1: people pointed out the glasses the guys wearing were totally contemporary.
Speaker 1: They existed in the forties. They the leather side guards
Speaker 1: were a little antiquated. It wasn't something that you frequently
Speaker 1: saw in nineteen forties, but they did exist before then. Uh,
Speaker 1: And also that the print t shirt he's wearing was
Speaker 1: actually probably more of a sweater and cardigan layer with
Speaker 1: a with a logo knit on the sweaters. In fact,
Speaker 1: there's some guests that it probably was the logo of
Speaker 1: a local hockey team, So that kind of puts the
Speaker 1: the the lid on that particular one. Um, So there
Speaker 1: are other ones that I've seen h people who supposedly
Speaker 1: are time travelers. In some cases you would argue this
Speaker 1: could easily be photoshop, or it could just be a
Speaker 1: case of, you know, mistaking one thing that was actually
Speaker 1: quite common during that era as something that came from
Speaker 1: outside of that time. Sadly, no no actual hard evidence
Speaker 1: there either, and I am I am hurt to say that.
Speaker 1: So what else can we do? Maybe we could provide
Speaker 1: an incentive for time travelers to show up and and
Speaker 1: leave evidence of time travel. But to do that, we'd
Speaker 1: have to figure out what motivates time travelers, like what
Speaker 1: what would be considered valuable. I mean, if grabbing a
Speaker 1: drink with one of the most famous scientists of the
Speaker 1: modern age isn't enough to convince you to pop on
Speaker 1: over to Cambridge at noon and have some Champagne. I
Speaker 1: don't what is so. I'm not sure that we could
Speaker 1: come up with something even if time travel were possible now. Ultimately,
Speaker 1: I don't think time travel is going to be possible
Speaker 1: any time in our lifetimes. Like if we ever do
Speaker 1: design a time travel device, my guess is it's far
Speaker 1: into the future. And I also think that the scientists
Speaker 1: are right on the money that no one will be
Speaker 1: able to travel back further than the moment when the
Speaker 1: time travel machine was made. I think it far more
Speaker 1: likely that we will develop faster propulsion systems that will
Speaker 1: ultimately bring special relativity into the situation where we will
Speaker 1: have some discrepancies between how much time seems to have
Speaker 1: passed for one person versus another. But that's not quite
Speaker 1: the same thing, and I don't think it's going to
Speaker 1: be so dramatic as traveling at the speed of light.
Speaker 1: I don't think we're gonna get that fast, but we
Speaker 1: might get fast enough where you know, the clock on
Speaker 1: the ship is not going to match the clocks on Earth.
Speaker 1: We already have to account for this sort of stuff
Speaker 1: due to both special and general relativity with our satellite systems.
Speaker 1: I talked a bit about that in a recent episode
Speaker 1: about how special relativity has to do with the relative
Speaker 1: speed of various bodies traveling through spacetime. General general relativity
Speaker 1: involves time in its relationship with gravity, so both of
Speaker 1: those things affect the apparent passage of time for respective bodies.
Speaker 1: And again, it's all relative, right, because your experience of
Speaker 1: time is dependent upon those factors, And if those factors change,
Speaker 1: then the way your experience of time happens will like
Speaker 1: to you. It will seem the same until you meet
Speaker 1: up with somebody else who has been going through a
Speaker 1: different experience, and then you'll realize that they don't match up.
Speaker 1: And you might say, I don't understand only five minutes
Speaker 1: have gone by, and the other person says, no, you
Speaker 1: were gone for an hour, and because of the actual
Speaker 1: factors involved, you both could be right. It's the crazy
Speaker 1: thing about relativity. Man, it's awesome. I loved thinking about
Speaker 1: this stuff. I didn't really touch on things like wormholes
Speaker 1: and other hypothetical kind of possibilities, largely because they might
Speaker 1: end up being a promising way to look at the
Speaker 1: possibility of time travel. I didn't talk about faster than
Speaker 1: light travel either, because as far as we can tell,
Speaker 1: that's not really possible. Uh, but maybe in the future
Speaker 1: ha ha, I will co into those a little bit more.
Speaker 1: Maybe I can get somebody on who's kind of an
Speaker 1: expert in these sort of physical, uh these physics problems,
Speaker 1: and to talk about the possibilities and which ones are
Speaker 1: pure science fiction versus well, hypothetically that's possible, and which
Speaker 1: ones are no. We might totally do that. I'm very
Speaker 1: curious what about you, guys, And I'm also curious what's
Speaker 1: your favorite time travel movie? I want to I want
Speaker 1: to hear responses because there's so many out there, and
Speaker 1: my favorites change. I really like them Back to the
Speaker 1: Future series, even though if you look at it from
Speaker 1: a theoretical time travel point of view, it gets super messy.
Speaker 1: But I really like that series. Uh. I also really
Speaker 1: like Bill and Ted, and they're excellent adventure I think
Speaker 1: that one's a lot of fun. I really like time
Speaker 1: travel movies that don't take it too seriously, because time
Speaker 1: travel is hard to do well. But there are a
Speaker 1: few out there, a few serious sci fi movies that
Speaker 1: use time travel that do it quite well. Do you
Speaker 1: have any favorites I want to hear Also, if you
Speaker 1: have any suggestions for future episodes of tech Stuff. Whether
Speaker 1: it's a technology, maybe it's a company, maybe it's a
Speaker 1: person in tech. Let me know. Send me an email.
Speaker 1: The address is tech stuff at how stuff works dot com.
Speaker 1: You can go to our website that's tech Stuff podcast
Speaker 1: dot com. You'll find links to other ways to contact me,
Speaker 1: like on Facebook or Twitter. You'll find more information about
Speaker 1: the show. You'll find all the episodes there. Sorry, does
Speaker 1: a great job on that, so go check that out.
Speaker 1: You also can head on over to our store that's
Speaker 1: over at t public dot com slash tech stuff. Remember,
Speaker 1: every purchase you make goes to the show. We greatly
Speaker 1: appreciate it, and we're always having fun coming up with
Speaker 1: new and uh goofy designs. I mean it's me. You
Speaker 1: know it's gonna be goofy. I I gave up trying
Speaker 1: to be cool years ago after it was abundantly clear
Speaker 1: I would never achieve that status. So that's all right.
Speaker 1: I'm all right with who I am now, and that's
Speaker 1: it for me. I'll talk to you again really soon
Speaker 1: for more on this and bathands of other topics. Because
Speaker 1: it how stuff works dot com. Wh whe