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July 26, 2012 27 mins

How does time travel work? Could it ever cross the line from science fiction into science fact? Join Josh and Chuck -- along with a live audience at the 2012 Comic-Con -- as they explore the ins and outs of time travel.

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Speaker 1 (00:00):
Brought to you by the reinvented two thousand twelve Camray.
It's ready. Are you welcome to stuff you should know
from house Stuff Works dot com. Hey, and welcome to
the podcast pre rap. I guess it's what you call that,
a right, Chuck? Yeah, sure, prolog Forward is a good one. Um.

I'm Josh and that's Chuck, and we are introducing a
live podcast that we recorded in San Diego just a
little while ago. Wait, July twelve, I think I don't remember.
I believe it was the twelfth of July. It was
great fun though. At common Con. Yeah, it was a
big deal. Um, there were people who waited in line

to get in. Some of those very people didn't get
in got turned away to see us. That was weird.
All those people were sorry for the people that came
that weren't fans of the show, and if you happen
to be listening now, then welcome and thank you for
coming just out of interest. That was pretty weird, you know,
to see people They're like, I don't know who these

guys are, but it sounds interesting. Those were the three
people who had their arms crossed in front of their chests. Yeah,
expectantly and then disappointed. Um, so we're gonna just kind
of get into this. If if anything seems out of
place or you're freaked out by people laughing, just remember
it's the recording of a live podcast. Jerry did a

great job recording it, and um, so here's us doing
time travel at Comic Con two thousand twelve. But those,
if you don't know, we have a podcast called stuff.
You know, it's on a website called how stuff dot com,
our beloved website, and pretty soon we are going to

be on the Science Channel too in January. Right, Um,
time travel, Yeah, let's do Time Traveler. Everybody ready to
learn a little bit about time travel. We're just gonna
do our thing. We're recording this live. Everybody, say hi
to everybody who's not here. For fans of the show,
we have our producer, Jerry is actually here. I want

to say hi Jerry. Alright, brass tacks, Jerry, did you
press record yet? Okay? So we are recording kid alright,
so um chuck, gosh, have you ever heard of a
guy named Andrew Basaguel? I never know what to say

here because I do, But should I say now? Just
say maybe? Maybe? Okay? So let me tell you a
little bit about this guy. All right. He's a Seattle attorney.
Oh I know this guy, Okay, And ever since two
thousand four has been talking publicly about how he was
part of something that he says it was called Project Pegasus,
which was supposedly a DARPA initiative for time travel. Yeah,

the U. S. Government was using children because apparently children
were specifically suited for time travel, which I didn't know
more so than adults. We should say that this guy
is the only source for this information. That's kind of
a big qualifier, very much. Um. But so he does
have a pretty good story, like Um. Throughout the seventies,
from age seven to twelve, he uh did a lot

of Lincoln assignments. I guess he traveled to Gettysburg at
one point, um, where he was captured in a famous
Josephine Cobb photograph. And I went and looked, and I
mean it could be him. It's really blurry photographs. There
were several guys, but it was from eighteen sixty three,
so they didn't know what they were doing back then. Um.
And then he also traveled a Ford Steater several times,

where at one point he ran into another version of
himself from another time that had traveled back there for
that same night the Lincoln assassination, by the way, so um,
and all of this, by the way, was based on
technology that was made from schematics found among the personal
effects um of Nikola Tesla, that's who died in New York.
So supposedly the US government ransacked the department, came up

with us bill these time portals. Now, far be it
from me to cast this persions on another person's story,
Chuck in. My motto is to each his own always. Yes,
we should like clink swords when we say um. But
I would buy this guy's story a little more if
he said that he was traveling to the future. Because
after researching for this presentation it's doing a little bit

of time travel research, I found that there are a
lot of bona fide, legitimate physicist cosmologists who say that, yes,
it is entirely possible to travel to the future, and
we kind of do it every day. It's pretty exciting.
It's just yeah, it's it's true. Do you want to
talk about it now? Yeah? You know, Josh, there's an
old joke in the scientific community, in the time travel community,

about a Let me see if I get this right
about an immigrant who comes to the United States las
I would, I imagine, and he lost he lost his watch.
It's really sad. And he goes up to a science
tis and he says, please, what's this time? I don't
know what country that is. That's that's a general maybe
European act. Okay, he's European. And the scientist replies, I'm sorry,

you'll have to ask a philosopher. I'm just a physicist.
Kind of a silly joke, a good time travel scientists.
This kills it in lab rooms, but it is a
silly joke, but it really gets to the heart of
the matter. When you're talking time travel, it is very
much a philosophical question, and it is Uh, if time
flows like a river, like some people think, in one direction, Uh,

the question is can you stop that flow, can you
reverse that flow? Can you go back in time? Or
can you speed up the flow and go forward in time?
That's kind of the question. Yeah. I find it hardening
to see like physicists and philosophers getting along having a
beer talking about time traveler having their brains melt together. Um,
and you were talking about time flowing like a river.

Can I talk about my boy Stephen Hawking? Yeah? Sure,
Do we have any Hawking fans in here? Same here?
I love that guy. Yeah, he's my Hawking is my homeboy. Um.
Stephen Hawking was talking about how he wrote this this
really great article or essay or whatever you want to
call it for the Daily Mail of all people, UM

about time travel, and then he talks about time as
a river. He says, it's very poetically. It's like a
river because it flows in one direction, you know, and
we're all just kind of going along with it. But
it's also a bit like a river in that UM
in different spots, it travels at different speeds, and if
we can figure out how to exploit those different spots,

then we can get to like the brass texts of
time travel. Yeah, Hawking basically thinks you can travel into
the future. All you have to go is really really,
really really fast. And we're talking, uh, I think the
stat is the fastest thing ever was Apollo ten yea
thousand miles an hour. That's very very fast. If you

want a time travel wall, Hawking says, you need to
go two thousand times faster than that. That's really fast
man interject something. Sure, I actually did the math, and
Hawking got his math wrong way tim from what he
goes on to say that you need to get very
close to the speed of light. You have to go

like twenty thousand times more, not two thousands. So I
just corrected. Homeboy been hawking and it's math. And I
hope he doesn't hear this because there will be a
SmackDown afterward. I'm sure be like, oh, you know math,
huh well. And one of the big problems with going
that fast is fuel. In order to go that fast,
you need a humongous ship that can carry fuel enough

to travel. I think he said six years, like ramping
it up speed wise, right, And that's not very likely
at least any time. You would need the seed ship
to go towards the speed of light, accelerating constantly for
six years. And then like the fourth year you'd started
time travel, could you hit speed of light which is
like six d million miles an hour pretty fast? Um?

And then I think at that point time goes um
an hour on the ship equals two hours back on Earth,
so you're starting to travel into the future relative to
the Earth. Right. Then after another two years, you get
to like the speed of light, which is like six
hundred and sixty. That's when like a day, is it

a day? A day on the ship equals like a
year on Earth, which okay, then that's that's time travel.
It's that's very very fast. And if you turned around
and went back to Earth, you could be like, check
me out, I'm from the past. Because really, this is
another thing I figured out from from researching. This is
time travel is really it doesn't matter if you don't

have anyone to show it off to, Like you can
go travel out and outer space as long as you
want and live forever. But if no one's there to
see it, who cares? You know? Exactly the philosopher's exactly. Yeah,
So you go ahead. Are we at Carl Sagan or yeah, okay,
that's always a great question to ask, are we at

Carl Sagan? So Carl Sagan, who's my homeboy, has a
viewpoint that sort of body slams the skeptics of the world.
And I know there are skeptics, and skeptics like to
unite and tell people things a lot with great vigor,
but I am not one. I've always been more of
a molder than a scully you know what I'm saying,

And uh yeah, thank you for that. And here's what
Carl Sagan has to say, because basically what skepticals say is, well,
if you can dime travel, then why aren't we always
visited by time travels all the time? That's skeptics. That's
what skeptics sound like. I think we just said a
skeptical form there than and Dunning, he's gone. Uh So

Carl Sagan has this to say about gonna read it
because I cannot summarize it any better than he says it.
He says, first of all, it might be that you
can build a time machine to go into the future
but not into the past, and we don't know about it,
but couzy, because we haven't yet invented that time machine.
Little brain melting, but it makes sense. Secondly, it might
be that time travel into the past is possible, but

they haven't gotten to our time yet. They're just really
far into the future. And the further back in time
you go, the more expensive it is. That when I'm
a little bit like a little economics into it. Uh.
And then thirdly, maybe backward time travel is possible, but
only up to the moment that time travel is invented,

so we haven't invented it yet, so it can't come
to us. We are s o l So that is like, yeah,
you need to be drinking something to understand that. Uh
so No, not really, not really. He's just saying like
maybe there's like a like you just can't go back
beyond the point where time travel is invented. He's just
being a rabble rouser. And the final thing he says

is there's a possibility that time travel is really perfectly possible,
but it requires such a great advance on our technology
that the human civil is Asian will destroy itself before
they can invent it. That's the gloom and Doom one exactly.
But and segands raising all these points to say, like,
you know, if somebody's saying, if time travel is possible,
where are all the time travelers? And he's saying, hey,

hey man, keep an open mind. That's what he used
to say. And put on this turtleneck, right, let's all
just wear turtlenecks. Everyone will mellow out. And I like
Carl Sagan. And there was one other thing about um
hawkings view. He made a good point where if you
aren't a show off, and you don't need to time
travel just to impress your friends in the future. Um,

you could use the same ship that's going super super
fast towards the speed of light to just go to
other parts of the Milky Way. It would come in
handy very much for these long distance trips. Right. So, UM,
say you wanted to make it to the iryan Nebula,
you could do this several foul goption Chucks come in, Man,
you hear something, Joshing Chuck, come in this time pilot

John Hodgman speaking to you from the future. Hey, Hogy,
she probably shouldn't be talking to me because I can't
hear you. This is a time message. It only goes
in one direction backwards, and I'm not even sure that
I reached you. It all depends on if I got
the time coordinates correct time coordinates by the way, just

latitude and longitude and altitude and time. But listen, Josh
and Chuck, if you're getting this message, I need you
to do something. Things have gone horribly wrong and this
time stream and it's all because of something that happens
at comic conve that you are intimately involved with. Basically,
you piss off John Sweden because you's already pressn't so

I urge you look at a picture of John Sweden
and don't piss him off, because if you do, he
gets so angry and he hates podcasts and then he
becomes a dictator and and stops making movies. But if
you recognize him, I guarantee you he will make um
another season of Firefly completely. Also, Josh and checked that

person in the Wookie costume is not a Wookie. H Okay, Well,
I hope that fixes everything. It's really not good here
in the future, so I hope you can fix it.
I also hope that this message went to my time
stream in the past and didn't get booted off to
another multiverse, in which case is this is reaching you
in a different multiverse. Watch out for the flood and

ghostly piranha um. They will eat your face off. All right,
I've got to go. It's all the time I have
so to speak. Time pilot John Hodgman from Unnamed Future
signing off goodbye and wow, I was a guy. He

is always looking out or you never know when the
future John Hodgman is going to pop in. Does anyone
know what Joss Wheden looks like, Okay, we need to
pick later. He's not here. Is anyone going to the
firefly panel? Yeah, you better go get in lined right
after this? Yeah, which we should we talk about methods

of time travel? Maybe? Oh yeah, go ahead. Okay, So
if you're talking time travel, which we are, Uh, there
are two directions. You can go go into the future
or you can go into the past. I'm a past guy.
I'd always like to see the Old West. You were
going to see Old West? Well, I just want to
be a gun slinger. Yeah, and we're less right. But

if you want to advance into the future, here's what
you're gonna have to do. You're gonna have to exploit uh, spacetime,
which isn't the easiest thing in the world, but it's possible.
It actually happens every day up in the sky with
GPS satellites. I don't know that guy's nodding, he knows, uh,
But many of you may not know that these satellites
actually a crew an extra third of a billionth of

a second every day. It doesn't sound like much, but
it's time trouble and it's kind of cool. And the
reason this happens is time passes faster in orbit. Uh.
Down here on Earth. Basically, Earth is like a big
dope st Bernard like dragging on time, and all the
mass on Earth is just slowing down time in little

tiny increments. Out there in deep space, you don't have
to worry about that kind of thing. And that's called
gravi gravitational time dilation, and it's a real thing. Uh,
and we observe this all the time scientists. Two astronomers
do UH. When they see light in deep space. They'll
see light moving in uh in a straight line, and
if it gets close enough to a sufficiently large object

like say Sagittarius A, which have which has the mass
of four million sons, time will actually bend and they
see this, and it's called the gravitational lensing effect. So uh,
if you were to, let's say, travel to Sagittarius A
and circle it is black hole and if you don't
fall in, which would be bad, Actually it might be

pretty cool. It would be really what would be bad.
There's a word for it, like what happens to you
kind of It's called spaghettification, like the the infinite density
of the center of a black hole. Just finge you
out into a spaghetti version of yourself that is not
alive anymore. Could use that actually would be a good look. So, um,

if you were to be able to circle sagittaries a
for a little while, uh without falling in, you would
experience time at half the rate on Earth, which is
time trouble again, and you come back to Earth and
you show off for everybody. Yeah, and that's basically the
center of this sagittary, say, is a really super dense point.
It's called a singularity. But don't confuse that with the singularity,

two very different things. That's a that's another big future problem. Yeah,
I'll be in big trouble at the singularity. Yet, Can
I throw out some of my favorite, um, please, universal
cosmic anomalies? So Chuck was talking about a black hole. Um,
one of my favorites is called the carring or curring.
We can't figure out how you say it. Honestly, we looked,

We really looked, so probably for the rest of the
time when I say it, I'm gonna say curring or carring, Okay, okay, um.
And basically, this is like a black hole that forms
from a lot of neutron stars that have collapsed, and
neutron stars are about the size of Manhattan, but they
have like the mass of our sun, so they're super dense,
and a bunch of will form into this ring that

kind of turns into this whirlpool um and because of
the centrifugal force of these things, they're a singularity doesn't form.
Hence spaghettification doesn't befall you when you go through the
center of these things. But it's still a black hole, right.
They think that if you go through, though, it's a
one way ticket because probably on the other side is
what's called a white hole, which is the opposite of

a black hole, and it pushes light and matter out
away from it, so there's no way of getting back.
But it's still possible that you can travel through time
at the very least to another part of space. Yeah. Right,
So you want me to tell you about another one, Well,
this next one is my favorite. Oh, the the Einstein
rosen Bridge, which wow, that got applause. Yeah, and here

comes the rest also known as a wormhole. Yeah, but
everyone calls it a wormhole because like you couldn't have
a TV show called Through the Einstein rosen Bridge with
Morgan Freeman. I guess you could. But through the wormhole
with Morgan Freeman is like catchy, right, it's sexy. It
is very sexy, super sexy. Um. And so an Einstein

rosen bridge or a wormhole. Uh, it's it's kind of
actually easy to grasp if if you consider time or
space spacetime, it's like a flat sheet that you fold
it in half and you left some space in between, right,
and then you have a sheet if you want to demonstrate,
do you I like this? Uh? And then gravity is
pushing towards the center, towards this empty space in the middle.

So if you have the sheet like that and you
put like a baseball on either side, these depressions are
going to form that are kind of akin to um,
the bending of time time delation, gravitational time delations thing.
And if the depressions that they form connect, you've got
a wormhole. Boom. Yeah, and you may be able to
travel through this. No one knows for certain, but it's

this kind of like the physicist or at the point
now where they're like, oh, and there's also this other
weird thing and maybe you can travel through time and
that is that what they say, that's kind of what
they say. But so, Chuck is an Old West kind
of time travel guy. I like time travel of the
past two UM. I tend to think the time travel
of the future is the one we're gonna accomplish first.

But the reason most physicists pooh poo the idea of
traveling back in time is because paradoxes our eyes. And
when a paradox arises, usually that means like the point
is moot, Like you can't argue it any further with
a learned person. Yeah, we uh. This is a point
where we talk about something called causality. And everything we
know here on planet Earth, as I say, is based

on and in a time sense, it's based on cause
and effect, and it's a one way street. Something happens
first and that leads to something that happens after. You
can't have something. You can't have an effect without the cause, right,
And it's a one way street going then in that direction,
cause effect, cause effat, cause effects cause out and you
have um. One of the big, great famous paradoxes is

the grandfather paradox. Right, the status of all paradoxes, which
is it kind of demonstrates Yeah, this bums Chuck out
because the grandfather is like, it's like, what the grandfather
do you know? Um? But let's say that you went
back to kill your grandfather, right, you're an assassin. Maybe
you'll do anything for money, a looper if you will.
And uh, And you go back and you you walk

up to your grandfather and you shoot him and kill
him dead. But this is the vision of your grandfather
before he's conceived your father. Therefore you can't possibly exist. Therefore,
how could you get back to time travel in the
first place to kill yourself? That's so sad, it is,
said the grandmother. Paradox, that's where you go back. And

they couldn't call it that they did. They tried it
and they were like, go back and kill your grandmother?
Are you serious? They're like, can you just call a
grandfather at least because maybe he hits you once or something.
You know, at the very least he made you mow
the lawn for a nickel or something. Yeah, grandmother just
caddles you and pet you chicken and pie or at
least mine. Did you miss you miss Granny Bryant? Don't

you do? Um? Although she lived to be a hundred
I know that's a right hold age. That's a right
poled age. Um, that's called a sidebar. There's also so
that's a that's an inconsistent uh, inconsistent cause of loop night.
My favorite is the consistent cause a loop. Yeah, this
is pretty cool because it's paradox free, which means it

could actually happen. And there's a physicist named Paul Davies
who describes it like this. Let's say a math professor
travels into the future and steals this really valuable math theorem.
Then he goes back to the past and he gives
theorem to a student, and that student ends up growing
up to be the very person he stole it from.
Everyone's going pretty awesome. No one dies in paradox free, right.

My favorite example of this, though, is, um, well, we
have a special guest here named Brian who's gonna help
us with this. Come on up here, Brian. Everybody give
Brian a round of applause. So this is Brian. He's
going to read to us an example, an explanation of

probably the coolest example of a consistent causal loop. So Brian,
will you take it away? Probably the best demonstration of
a consistent causal loop is found in the film Back
to the Future. Towards the end of the movie, Marty
McFly performs Johnny be Good on his guitar during the
enchantment under the Sea Dance. His playing catches the attention

of one Marvin Barry, cousin of the famed musician Chuck Berry.
His interest, Pete Marvin calls Chuck Berry to alert him
to this unusual sound, which prompts we must assume Chuck
Berry to write and record Johnny Be Good. But since
he is from the future, we must assume that Marty
McFly learned to play the song Johnny Be Good in
his own time based on the song recorded by Chuck
Berry years in the past. This is impossible, however, because

it was Marty McFly's performance of Johnny Be Good that
prompted its creation. This paradox, where the origination of a
thing comes as the result of time travel, violates the
law of causality a truly important lie. Indeed, it's true
that we could have also cited the Pocket Watch and
the Christopher Reave movie Somewhere in Time as an example,
but Back to the Future was a way better movie.

All right, right, very much time, Nicety Good? Thanks well down,
to and then the final possibility, uh is my favorite one,
which is many worlds, parallel universes. You can times. I
saw some head nods. People love that one because he
can time travel all over the place. Man, And you're
just create separate timelines and you're in many different sandboxes,

and it just doesn't even matter, right because if you
go back and kill your grandfather in another version of
the universe where you weren't born, who cares? Who cares? Man,
because I'll just go in another timeline. Do you know
why are you talking like that? Because that's what they
hit these like, Man, Yeah, are you do you want
to stumma? I guess in summation. You know, we certainly

don't know if it's for sure possible, but I think
it's important to ask these questions. You know, with people
like Stephen Hawking and Carl Sagan and sixth century philosophers
are talking about slowing down time and speeding up time,
then it's worthwhile to me, agreed, And that's a That
is our presentation on time travel. Thanks so um, I

think we're about out of time unless we have a
few minute for Q and A. Do we one question?
Let's do one question? Let's do too quick. Your hand up,
there's a microphone right there. Nice rocket. Have either of
you ever wanted to be on Celebrity Jeopardy so you
could just smoke them? Thank you? I would love to

be on Jeopardy. I don't know if we qualified for
Celebrity Jeopardy yet, but I used to sit around in
college all the time and play with my roommates. Uh
and I did pretty well. I thought. I think that
the X factor is whether or not you freeze on TV.
So one more, one more bam in the hat in
the back baseball hat. You just yeah, yeah, yeah, yeah,

thank you for John. Hello. H question, do you are
you guys gonna like do books like you know, how
do you have the little books so and all this stuff?
Are you gonna like release those eventually or do you
plan on it? We have two audio books which are
like books, but they're way easier than um. But yeah,

that's stuff. We've definitely talked about that before, like we're
still trying to figure out what the idea would be
behind it, but um, yes, we're definitely not opposed to that.
So look for in like maybe yes, we get all
time job there right now exactly so um, let's see.
If you want to get in touch with us, you
can tweet to us on s Y s K podcast,
you can visit us on Facebook dot com, and you

can always send us a good old fashioned email by
wrapping it up, spanking it on the bottom and sending
it off to Stuff Podcast at Discovery dot coms and
very much everybody for more on this and thousands of

other topics, does it how stuff works dot com h
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