June 17, 2010 • 17 mins
In the second episode of this two-part series, Robert and Allison check out the possibilities of travelling into the past. From wormholes to the grandfather paradox, there are many arguments for -- and against -- time travel. Tune in and learn more.
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Episode Transcript
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Speaker 1 (00:01):
Welcome to stuff from the Science Lab from how stuff
works dot com. Hey guys, and welcome to the podcast.
This is Alisoon dotom elk the science Center how stuff
works dot com. And this is Robert Lamb, science for
Rider at how stuffworks dot com. Hey Allison, Hey Robert.
(00:24):
Have you ever traveled back in time? M hmm, no,
have you? No? I haven't, so I guess we're woefully
unprepared for this podcast. We were talking about traveling back
in time. It's part two or part one of our series.
What order you're taking? Yeah, we already covered traveling into
the future in our first installment. And you know what,
(00:47):
traveling back in time is not as easy as traveling forward. No.
I mean, as we pointed out in the last one.
I mean we're all traveling into the future at a
very slow right every day. But traveling into the past,
it's not happened naturally. Yeah, you get a lot more
stumbling blocks. So like, for example, the name of our podcast,
Hey grandpa, you have the very famous grandfather paradox. Yeah,
(01:09):
you want to hit this one. This is a this
is a pretty uh pretty It's one of one of
the great things about time travels, just thinking about the
problems of time travel into the past, and the grandfather
paradox is one of the big ones. And you guys
have probably heard of this, but for the sake of
there's people who haven't. Okay, so the grandfather paradox is
pretty cool. Basically, the idea is, if you were to
(01:30):
go back in time and kill your own grandfather, what
would happen. It's like, I'm going to go back in
time and and kill my grandfather. Bam, my grandfather is
dead in the past. That means he never meets my grandmother.
They never have a kid, and they never have a kid.
I'm never born, so I never go back in time
to kill my grandfather. Right, how do you reconcile these things?
(01:52):
They're in laws? The paradox. Yeah, anything you would go
back in time to fix by fixing it, you would
you would destroy the need that arose to go back
and fix it. You would destroy the problem and then
with me a problem to fix. It's like this loop. Yeah,
and this also gets that another big problem with backward
time travel in that it violates the rule of causality,
cause and effect. Um. This is a big one for Hawking.
(02:14):
He's always talking about this when he talks about time travel. Yeah,
I mean, it's like a fundamental aspect of the universe,
and that cause comes before effect, and if effect came
before cause, that would be that would be crazy. That's
like having dessert before your meal, you know. Plus it
just doesn't sound as good affect and cause that doesn't
rull off the tongue. Yeah, not at all. And just
because the French do eat salad at the end of
(02:36):
their meals doesn't make it right. No, that's it's clearly
they're toying with forces beyond our comprehension. So while I
was researching this program, I came across Carl Sagan's interview
with a PBS their Nova program, and and Nova asked
him whether you thought backwards time travel would ever be possible,
And Sagan had this to say, such questions are purely
a matter of evidence, and if the evidence is inconsistent
(03:00):
or insufficient, then we withhold judgment until there's better evidence.
Right now, we're in one of those classic, wonderfully evocative
moments in science when we don't know, when there are
those on both sides of the debate, and when what
is at stake is very mystifying and very profound. Indeed,
as long as we're talking about Sagan, we should talk
about wormholes. Yeah. Yeah, he's one of the big the
(03:22):
big names behind wormholes, right, or the big inspiration for
research into wormholes, right, yeah, the because of his book Contact.
Did you ever Recontact that way? Now? I saw the movie,
Jodie Foster didn't, really don't. I just recently read that
the character of Ellie Earraway was based on the real
life study explorer UM and scientist Jill Tarter. Sorry Jill
(03:44):
if I just muled your last name. All right, So
what is a wormhole? Right? Do you guys remember these
from Rinkle in Time? Did you read Wrinkle on Time? No,
that's one of those series I should have read, but
you should. You should. In fact, I'm going to go
back and read it. It's amazing. So a wormhole is
a hypothetical structure, right, A long, thin tunnel connecting two
points in space time, um, the way I like to
(04:06):
imagine it. And I know there's some sort of a um,
there's some sort of cool analogy involving an aunt. Right,
But I think back to the movie Event Horizon, which
is kind of a kind of a crappy, kind of
a fun sci fi horror film where like they fly
a spaceship into a black hole and travel to Hell
or something. But there's a scene where Sam Neil of
Jurassic Park fame is explaining something and he takes like
(04:28):
a poster off the wall and he folds it right
so that point A that's on the far side of
the one fast end of the sheet, and point B
on the other far into the sheet. He be binds
the paper until those two are touching back to back,
and then he shoves a pencil through the through both
holes and bang, there's our warm hole. Right, thank you,
Sam Neil. Yeah, that's the one good thing you can
(04:49):
get out of that movie. Yeah. The other one I've
heard is really similar. You squish a piece of paper together,
you get ant, say, the ant pokes a hole through it,
and the aunt doesn't want to travel that far. That's
like a universe to go from one then of the
piece of paper to another, so it just travels through
the little wormhole and the couple of piast paper to
get where it's going. So there you have it. Aunts,
Masters of space and Time, not really. Yeah. Wormholes are
(05:11):
also called Einstein Rosen bridges and which sounds like something
you would get done at a dental office, so no
wonder that one didn't stick. Yeah, and John Wheeler was
thought to have come up with the original term of wormhole,
and they're considered possible because they very nice leaping into
Einstein's theory of relativity, which, as you guys probably remember,
states that any mass curve spacetime. And the nice thing
(05:34):
about wormholes is that when you're talking about traversing a wormhole,
you're still talking about going at speed slower than the
speed of light. A lot of the study into wormholes
comes back to contact again, right, Yeah. Most recently thorn
Um Kip Thorne in particular got into it when Carl
Sagan as Thorne, who has done a physicist at cal
Tech with help for getting the protagonist in Contact, which
(05:56):
we just we're talking about Ellie air Away. He wanted
to get Eli to travel faster to a distant star
and he needed a means together there, so he asked
Thorn for some help, and Thorne of course suggested a wormhole.
He plugged a hole in a plot by creating a
hole in space time. Well Well done, Robert, well done.
And hockeying is also pretty big in this area. Um.
But let's get back to Thorne for a second. Thorne
(06:17):
slots even led to an idea for a time travel
machine based on these things called thorn plates. And we're
actually not going to get into them today because I
think that would be really hard to explain over a podcast,
but there is a there is an idea for a
time travel machine based on thorn Thorne's other big contribution
was he put the kibosh on care holes. So, according
(06:37):
to good old Kevin Bonser, who wrote the article on
time travel on her site, care holes are these rotating
black holes that could be used as portals for time
travel or traveled to parallel universes. So in there is
this New Zealand mathematician by the by the name of
Roy care and he proposed the first realistic theory for
a black hole. So there are a few problems with wormholes,
(06:59):
aside from the fact that they're purely hypothetical and might
not even be real at all. And there's that, and that,
and that is that, um, if we were able to
create one or find one, because their theories that they
like occur naturally at the quantum level, like just momentarily,
like in the quantum foam, which always makes me think
(07:19):
of pie for some reason. Really, it makes me think
of a temper pedic mattress. Yeah, I think it's like
a green like c foam pie. Is that a thing?
A c foam pie? No green pie? Maybe I think
that it was like a dessert my mom made or
something foam pie. That sounds revolting, Robert, Sorry, Robert's mom. Well,
the dessert was good, but my recollection of it maybe
(07:40):
a little afraid. But um, no way, I would like
to sleep on quantum foam. Didn't you think that would
be nice? Yeah? But if it has wormholes in it,
it's it might be problematic because these things, these things
would be like popping in and out of existence. In
each one would be a little tunnel to some other
corner of time and space, you know. Might be it
might lead to the center of a black hole. Might
we do a planet where like you know, kangaroos, rule
(08:04):
might go into the future, might go into the past.
You don't know, And they're just popping in and out
of existence. But if you could grab one, you could
you could theoretically use some sort of unrealized technology to
like pull it open. Expanded enough to like fly spaceship
through or something. Right, Well, they speculate that keeping one
open would require exotic matter or a matter that has
a net negative mass energy density, which is handy for
(08:26):
pushing things apart, right, and that stuff hard to find. Yeah,
I think it is. I don't think about any but so, yeah,
there's there's that UM. And then also there's some theories
that if you could get one and you could actually
hold it open, there would be like so much radiation
heading into the wormhole that it would fry you, or
it would create a radiant there would be like a
(08:47):
radiation feedback loop, kind of like what happens with with
audio equipment. Yeah, this is Hawking's big thing. Yeah, that
it would be like in the same way that that
audio feedback could destroy a speaker. Um, it would destroy
the warmhole and whatever you were trying to throw back
through it, you know, your your terminators or time machines
or whatever. But luckily there are other equally high pothetical
(09:09):
theories out there. There are. Indeed, one of them is
the cosmic string slash got loop soon as User's guide
to time Travel on wired uh. The n YU theoretical
physicist Michio Kaku mentions one method thought up by ninety
one Princeton physicist J. Richard Gott. And this involves searching
(09:30):
for an infinitely long cosmic string leftover from the Big Bang.
Have you seen it? It It is lying around the universe lately,
not recently. I think what you need is a some
sort of a cosmic kitten. Right, that's a horrible joke.
I can't believe we just made that. So once you
find such a string, you arrange it in a rectangle
shape that's roughly fifty four thousand light years long and
(09:51):
point zero one light years wide. He's in gravity, so
that's fine. You just bang that out in an afternoon.
This is just this is another one of those. It's
like a thought experiment, and it's um you know, it's
it's purely hypothetical. Um. Right. So God's idea is that
the strings could warp space time in such a way
as to allow backwards time travel. It wouldn't be good
for four time travel, though, So let's move on to
(10:11):
the next one. Yeah, this and this is the giant cylinder. Yeah,
it's the Van stoke Um cylinder, which which sounds like
a pretty good uh like country band name, I think UM.
And this idea is that you get a huge cylinder,
in fact, a cylinder so big that it's it's infinite,
so even you know, just more astronomical to even try
(10:32):
and uh, you know, envision all right, you get this.
So you get this enormous cylinder, get it spinning at
near light speed. We don't want to we don't want
to go faster than light speed because we don't want
to get silly here with this stuff, this scheme UM,
and it would anyway, it gets going real fast and
it ends up dragging space time and into its rotation.
So in nineteen four, Frank J. Tippler, a cosmologist and physicist,
(10:55):
pointed out that the field surrounding the cylinder would violate
causality quote unquote in the sense that it allows it
closed a timelike line to connect any two events and
space stop. This suggests that a finite rotating cylinder would
also act as a handy time machine. Okay, he didn't
say handy, he just said as a time machine. Yeah,
there's there's nothing handy about this cylinder idea. But again,
(11:17):
it's it's all about it's not about saying, hey, here's
a realistic time travel device. It's kind of like, all right,
these are the this is what we're up against in
the universe. What would it take to break the laws
of the universe and make it possible? Yeah? Right, And
let's not forget that science builds on other science, so
you have to get some wacky ideas out there to
get some realistic ones. But let's stick with unrealistic for
(11:41):
another For yet another segment, let's stock takeions. Yeah, so,
like we've mentioned, according to the Einstein's theory of relativity,
nothing can go faster than light. Light is the universal
speed limit. But take eons are the universal speed limit breakers, right. Indeed,
they are going to get pulled over by the universal cops.
But they're too speedy. So ordinary matter is prevented from
(12:03):
ever reaching the speed of light because of the fact
that it would require infinite energy. Takeons, of course, are
no ordinary matter, and of course they're hypothetical, although they
do make an appearance on Star Trek and in the
Skeptics Dictionary. Check it out. In the Skeptics Dictionary, it
says that there's a whole line of New Age products
that range from beads, belts, and shoe inserts to sweat bands,
power pillars, massage oils, and volley files of take on water.
(12:26):
If that's true, those guys can make a mint showing
physicists where to get some take so the new Agers
can figure out where to get them about the physicists can't.
Nazis take is that if takeons exist, the universe could
be filled with them, but they interact so weekly with
ordinary matter that we couldn't detect them. So far, none
of the big accelerator labs have detected an interaction which
(12:49):
can only be explained by tachons. So let's say I
were to order a bunch of take eons from my
New Age supplier and they were actually real takeions, not
not fake tachons. Um is that, how do I go
back in time with these guys? So we just wrote
an article on this for Through the Wormhole for Discovery,
and it was on quantum nonlocality entangled physics and in
(13:09):
fact take on. So here's the experiment that one of
the writers, Susan Nassar, came up with. Pretend all the
clocks in the world are broken. Okay, done, Just forget
about having any means to tell time. Instead, just imagine
point A and point B. Okay, so we're gonna say
that time has moved forward when light leaving A reaches by.
(13:32):
When light leaves A, it's now, but when it reaches
B it's later. Okay, Now add a take in into
the mix, and which you'll remember it travels faster than light,
so no surprise here. You're going to release the photon
and the tacon at the same time, and the sub
atomic particle is going to reach B first, not the photon.
(13:53):
So when it reaches B, what time is it? It's before? Now? Okay,
what happened? Did it move backward in time? It's kind
of an interesting thought experiment. Okay, so think of think
of the photon as the turtle and the take eon
as the hair exactly. And so when the turtle, the
(14:13):
turtle leaves point A now and when he arrives at
point point B it's later. But the problem here is
the hair beats him to point B, so he gets
there before now. But the handy thing about takons is
there hypothetical So they so the tortoise, as usual, wins
the race because that hair, it just it can never
pull it off. That sounds a little crazy. They are
(14:35):
in fact a little crazy, and that is in fact
where we're going to wrap up today's podcast on backwards
time travel. I'm gonna get myself some tachions though. If
any anybody wants to supply me with take eons uh
dis contact me hook me up. So as always, you
can type time travel into a search bar on her
homepage and see what good stuff that brings up. Stuff
(14:57):
on warp drives, which we didn't cover today, or time
travel or weather space is a shape, all that good stuff.
And we are all over social networking, aren't we, robbert
Um And hey, why do we have all these pictures
of lizards? We do have some pictures of lizards. Listener mail, Yeah,
we got listening mouth from bath and Beth writes, Hi,
(15:21):
I really enjoy your podcast. Thanks for investigating such cool
topics and for putting it up for free. I'm a
graduate student in ecology and evolutionary biology staying lizards, so
I was especially interested in your podcast on regeneration. That
was a fun one, Yeah, Beth writes I was thus
a little sad when you didn't talk about tail loss
and regrowth and lizards, although I agree that salamanders are
(15:42):
definitely more impressive, and then she goes on to write,
lizard tails don't regenerate in the same way that salamander
lives limbs do reground tails have a tube of cartilage
in the center rather than bothe. Nonetheless, I thought you
might enjoy seeing a photo of a lizard with a
funny looking fork tail that I caught during recent field work,
and that she sent three photo us and the lizard. Indeed,
how's this fork tail? Which is really unusual? And I'm
(16:04):
just going to assume that she did not pull the
tail off that lizard just to impress us. No, I
do not think that's it. That she writes that I
think would probably happened was that she suffered a tailbreak
the lizard she started to regenerate her tail and then
had to partial break higher up than stimulated new tail
growth from the broken part, even though the rest of
the tail is still attached. It sounds complicated, but the
pictures are well worth it. So yeah, send us send
(16:27):
us pictures of your lizard tales and various other things.
We we would love to get them. Uh. And you
have another another letter doing it? I do, I do?
I have one from an Aussie uh And Karen writes,
Hey guys, First, I'd like to say I love the
various topics you choose. I'm quite handy at quiz Nights
thanks to you. My only grip is how you pronounced
in Australian cities in terms. For instance, Geelong isn't with
(16:49):
a hard G like engulf, it's a soft G like
G that's long. Perhaps project casting you could check an
AUSEE site as to how we pronounce things. Very sorry, Karen,
we apologize and we will indeed follow up on that
aggestion in the future. Yeah, all Australian websites are blocked
on our server. I don't know what's up with that,
So if you guys want to send us an email,
(17:09):
you know where to find us. Science stuff at has
Differs dot com for more on this and thousands of
other topics. Does it how stuff works dot Com. Want
more how stuff works, check out our blogs on the
house stuff works dot com home page
Welcome to stuff from the Science Lab from how stuff
works dot com. Hey guys, and welcome to the podcast.
This is Alisoon dotom elk the science Center how stuff
works dot com. And this is Robert Lamb, science for
Rider at how stuffworks dot com. Hey Allison, Hey Robert.
(00:24):
Have you ever traveled back in time? M hmm, no,
have you? No? I haven't, so I guess we're woefully
unprepared for this podcast. We were talking about traveling back
in time. It's part two or part one of our series.
What order you're taking? Yeah, we already covered traveling into
the future in our first installment. And you know what,
(00:47):
traveling back in time is not as easy as traveling forward. No.
I mean, as we pointed out in the last one.
I mean we're all traveling into the future at a
very slow right every day. But traveling into the past,
it's not happened naturally. Yeah, you get a lot more
stumbling blocks. So like, for example, the name of our podcast,
Hey grandpa, you have the very famous grandfather paradox. Yeah,
(01:09):
you want to hit this one. This is a this
is a pretty uh pretty It's one of one of
the great things about time travels, just thinking about the
problems of time travel into the past, and the grandfather
paradox is one of the big ones. And you guys
have probably heard of this, but for the sake of
there's people who haven't. Okay, so the grandfather paradox is
pretty cool. Basically, the idea is, if you were to
(01:30):
go back in time and kill your own grandfather, what
would happen. It's like, I'm going to go back in
time and and kill my grandfather. Bam, my grandfather is
dead in the past. That means he never meets my grandmother.
They never have a kid, and they never have a kid.
I'm never born, so I never go back in time
to kill my grandfather. Right, how do you reconcile these things?
(01:52):
They're in laws? The paradox. Yeah, anything you would go
back in time to fix by fixing it, you would
you would destroy the need that arose to go back
and fix it. You would destroy the problem and then
with me a problem to fix. It's like this loop. Yeah,
and this also gets that another big problem with backward
time travel in that it violates the rule of causality,
cause and effect. Um. This is a big one for Hawking.
(02:14):
He's always talking about this when he talks about time travel. Yeah,
I mean, it's like a fundamental aspect of the universe,
and that cause comes before effect, and if effect came
before cause, that would be that would be crazy. That's
like having dessert before your meal, you know. Plus it
just doesn't sound as good affect and cause that doesn't
rull off the tongue. Yeah, not at all. And just
because the French do eat salad at the end of
(02:36):
their meals doesn't make it right. No, that's it's clearly
they're toying with forces beyond our comprehension. So while I
was researching this program, I came across Carl Sagan's interview
with a PBS their Nova program, and and Nova asked
him whether you thought backwards time travel would ever be possible,
And Sagan had this to say, such questions are purely
a matter of evidence, and if the evidence is inconsistent
(03:00):
or insufficient, then we withhold judgment until there's better evidence.
Right now, we're in one of those classic, wonderfully evocative
moments in science when we don't know, when there are
those on both sides of the debate, and when what
is at stake is very mystifying and very profound. Indeed,
as long as we're talking about Sagan, we should talk
about wormholes. Yeah. Yeah, he's one of the big the
(03:22):
big names behind wormholes, right, or the big inspiration for
research into wormholes, right, yeah, the because of his book Contact.
Did you ever Recontact that way? Now? I saw the movie,
Jodie Foster didn't, really don't. I just recently read that
the character of Ellie Earraway was based on the real
life study explorer UM and scientist Jill Tarter. Sorry Jill
(03:44):
if I just muled your last name. All right, So
what is a wormhole? Right? Do you guys remember these
from Rinkle in Time? Did you read Wrinkle on Time? No,
that's one of those series I should have read, but
you should. You should. In fact, I'm going to go
back and read it. It's amazing. So a wormhole is
a hypothetical structure, right, A long, thin tunnel connecting two
points in space time, um, the way I like to
(04:06):
imagine it. And I know there's some sort of a um,
there's some sort of cool analogy involving an aunt. Right,
But I think back to the movie Event Horizon, which
is kind of a kind of a crappy, kind of
a fun sci fi horror film where like they fly
a spaceship into a black hole and travel to Hell
or something. But there's a scene where Sam Neil of
Jurassic Park fame is explaining something and he takes like
(04:28):
a poster off the wall and he folds it right
so that point A that's on the far side of
the one fast end of the sheet, and point B
on the other far into the sheet. He be binds
the paper until those two are touching back to back,
and then he shoves a pencil through the through both
holes and bang, there's our warm hole. Right, thank you,
Sam Neil. Yeah, that's the one good thing you can
(04:49):
get out of that movie. Yeah. The other one I've
heard is really similar. You squish a piece of paper together,
you get ant, say, the ant pokes a hole through it,
and the aunt doesn't want to travel that far. That's
like a universe to go from one then of the
piece of paper to another, so it just travels through
the little wormhole and the couple of piast paper to
get where it's going. So there you have it. Aunts,
Masters of space and Time, not really. Yeah. Wormholes are
(05:11):
also called Einstein Rosen bridges and which sounds like something
you would get done at a dental office, so no
wonder that one didn't stick. Yeah, and John Wheeler was
thought to have come up with the original term of wormhole,
and they're considered possible because they very nice leaping into
Einstein's theory of relativity, which, as you guys probably remember,
states that any mass curve spacetime. And the nice thing
(05:34):
about wormholes is that when you're talking about traversing a wormhole,
you're still talking about going at speed slower than the
speed of light. A lot of the study into wormholes
comes back to contact again, right, Yeah. Most recently thorn
Um Kip Thorne in particular got into it when Carl
Sagan as Thorne, who has done a physicist at cal
Tech with help for getting the protagonist in Contact, which
(05:56):
we just we're talking about Ellie air Away. He wanted
to get Eli to travel faster to a distant star
and he needed a means together there, so he asked
Thorn for some help, and Thorne of course suggested a wormhole.
He plugged a hole in a plot by creating a
hole in space time. Well Well done, Robert, well done.
And hockeying is also pretty big in this area. Um.
But let's get back to Thorne for a second. Thorne
(06:17):
slots even led to an idea for a time travel
machine based on these things called thorn plates. And we're
actually not going to get into them today because I
think that would be really hard to explain over a podcast,
but there is a there is an idea for a
time travel machine based on thorn Thorne's other big contribution
was he put the kibosh on care holes. So, according
(06:37):
to good old Kevin Bonser, who wrote the article on
time travel on her site, care holes are these rotating
black holes that could be used as portals for time
travel or traveled to parallel universes. So in there is
this New Zealand mathematician by the by the name of
Roy care and he proposed the first realistic theory for
a black hole. So there are a few problems with wormholes,
(06:59):
aside from the fact that they're purely hypothetical and might
not even be real at all. And there's that, and that,
and that is that, um, if we were able to
create one or find one, because their theories that they
like occur naturally at the quantum level, like just momentarily,
like in the quantum foam, which always makes me think
(07:19):
of pie for some reason. Really, it makes me think
of a temper pedic mattress. Yeah, I think it's like
a green like c foam pie. Is that a thing?
A c foam pie? No green pie? Maybe I think
that it was like a dessert my mom made or
something foam pie. That sounds revolting, Robert, Sorry, Robert's mom. Well,
the dessert was good, but my recollection of it maybe
(07:40):
a little afraid. But um, no way, I would like
to sleep on quantum foam. Didn't you think that would
be nice? Yeah? But if it has wormholes in it,
it's it might be problematic because these things, these things
would be like popping in and out of existence. In
each one would be a little tunnel to some other
corner of time and space, you know. Might be it
might lead to the center of a black hole. Might
we do a planet where like you know, kangaroos, rule
(08:04):
might go into the future, might go into the past.
You don't know, And they're just popping in and out
of existence. But if you could grab one, you could
you could theoretically use some sort of unrealized technology to
like pull it open. Expanded enough to like fly spaceship
through or something. Right, Well, they speculate that keeping one
open would require exotic matter or a matter that has
a net negative mass energy density, which is handy for
(08:26):
pushing things apart, right, and that stuff hard to find. Yeah,
I think it is. I don't think about any but so, yeah,
there's there's that UM. And then also there's some theories
that if you could get one and you could actually
hold it open, there would be like so much radiation
heading into the wormhole that it would fry you, or
it would create a radiant there would be like a
(08:47):
radiation feedback loop, kind of like what happens with with
audio equipment. Yeah, this is Hawking's big thing. Yeah, that
it would be like in the same way that that
audio feedback could destroy a speaker. Um, it would destroy
the warmhole and whatever you were trying to throw back
through it, you know, your your terminators or time machines
or whatever. But luckily there are other equally high pothetical
(09:09):
theories out there. There are. Indeed, one of them is
the cosmic string slash got loop soon as User's guide
to time Travel on wired uh. The n YU theoretical
physicist Michio Kaku mentions one method thought up by ninety
one Princeton physicist J. Richard Gott. And this involves searching
(09:30):
for an infinitely long cosmic string leftover from the Big Bang.
Have you seen it? It It is lying around the universe lately,
not recently. I think what you need is a some
sort of a cosmic kitten. Right, that's a horrible joke.
I can't believe we just made that. So once you
find such a string, you arrange it in a rectangle
shape that's roughly fifty four thousand light years long and
(09:51):
point zero one light years wide. He's in gravity, so
that's fine. You just bang that out in an afternoon.
This is just this is another one of those. It's
like a thought experiment, and it's um you know, it's
it's purely hypothetical. Um. Right. So God's idea is that
the strings could warp space time in such a way
as to allow backwards time travel. It wouldn't be good
for four time travel, though, So let's move on to
(10:11):
the next one. Yeah, this and this is the giant cylinder. Yeah,
it's the Van stoke Um cylinder, which which sounds like
a pretty good uh like country band name, I think UM.
And this idea is that you get a huge cylinder,
in fact, a cylinder so big that it's it's infinite,
so even you know, just more astronomical to even try
(10:32):
and uh, you know, envision all right, you get this.
So you get this enormous cylinder, get it spinning at
near light speed. We don't want to we don't want
to go faster than light speed because we don't want
to get silly here with this stuff, this scheme UM,
and it would anyway, it gets going real fast and
it ends up dragging space time and into its rotation.
So in nineteen four, Frank J. Tippler, a cosmologist and physicist,
(10:55):
pointed out that the field surrounding the cylinder would violate
causality quote unquote in the sense that it allows it
closed a timelike line to connect any two events and
space stop. This suggests that a finite rotating cylinder would
also act as a handy time machine. Okay, he didn't
say handy, he just said as a time machine. Yeah,
there's there's nothing handy about this cylinder idea. But again,
(11:17):
it's it's all about it's not about saying, hey, here's
a realistic time travel device. It's kind of like, all right,
these are the this is what we're up against in
the universe. What would it take to break the laws
of the universe and make it possible? Yeah? Right, And
let's not forget that science builds on other science, so
you have to get some wacky ideas out there to
get some realistic ones. But let's stick with unrealistic for
(11:41):
another For yet another segment, let's stock takeions. Yeah, so,
like we've mentioned, according to the Einstein's theory of relativity,
nothing can go faster than light. Light is the universal
speed limit. But take eons are the universal speed limit breakers, right. Indeed,
they are going to get pulled over by the universal cops.
But they're too speedy. So ordinary matter is prevented from
(12:03):
ever reaching the speed of light because of the fact
that it would require infinite energy. Takeons, of course, are
no ordinary matter, and of course they're hypothetical, although they
do make an appearance on Star Trek and in the
Skeptics Dictionary. Check it out. In the Skeptics Dictionary, it
says that there's a whole line of New Age products
that range from beads, belts, and shoe inserts to sweat bands,
power pillars, massage oils, and volley files of take on water.
(12:26):
If that's true, those guys can make a mint showing
physicists where to get some take so the new Agers
can figure out where to get them about the physicists can't.
Nazis take is that if takeons exist, the universe could
be filled with them, but they interact so weekly with
ordinary matter that we couldn't detect them. So far, none
of the big accelerator labs have detected an interaction which
(12:49):
can only be explained by tachons. So let's say I
were to order a bunch of take eons from my
New Age supplier and they were actually real takeions, not
not fake tachons. Um is that, how do I go
back in time with these guys? So we just wrote
an article on this for Through the Wormhole for Discovery,
and it was on quantum nonlocality entangled physics and in
(13:09):
fact take on. So here's the experiment that one of
the writers, Susan Nassar, came up with. Pretend all the
clocks in the world are broken. Okay, done, Just forget
about having any means to tell time. Instead, just imagine
point A and point B. Okay, so we're gonna say
that time has moved forward when light leaving A reaches by.
(13:32):
When light leaves A, it's now, but when it reaches
B it's later. Okay, Now add a take in into
the mix, and which you'll remember it travels faster than light,
so no surprise here. You're going to release the photon
and the tacon at the same time, and the sub
atomic particle is going to reach B first, not the photon.
(13:53):
So when it reaches B, what time is it? It's before? Now? Okay,
what happened? Did it move backward in time? It's kind
of an interesting thought experiment. Okay, so think of think
of the photon as the turtle and the take eon
as the hair exactly. And so when the turtle, the
(14:13):
turtle leaves point A now and when he arrives at
point point B it's later. But the problem here is
the hair beats him to point B, so he gets
there before now. But the handy thing about takons is
there hypothetical So they so the tortoise, as usual, wins
the race because that hair, it just it can never
pull it off. That sounds a little crazy. They are
(14:35):
in fact a little crazy, and that is in fact
where we're going to wrap up today's podcast on backwards
time travel. I'm gonna get myself some tachions though. If
any anybody wants to supply me with take eons uh
dis contact me hook me up. So as always, you
can type time travel into a search bar on her
homepage and see what good stuff that brings up. Stuff
(14:57):
on warp drives, which we didn't cover today, or time
travel or weather space is a shape, all that good stuff.
And we are all over social networking, aren't we, robbert
Um And hey, why do we have all these pictures
of lizards? We do have some pictures of lizards. Listener mail, Yeah,
we got listening mouth from bath and Beth writes, Hi,
(15:21):
I really enjoy your podcast. Thanks for investigating such cool
topics and for putting it up for free. I'm a
graduate student in ecology and evolutionary biology staying lizards, so
I was especially interested in your podcast on regeneration. That
was a fun one, Yeah, Beth writes I was thus
a little sad when you didn't talk about tail loss
and regrowth and lizards, although I agree that salamanders are
(15:42):
definitely more impressive, and then she goes on to write,
lizard tails don't regenerate in the same way that salamander
lives limbs do reground tails have a tube of cartilage
in the center rather than bothe. Nonetheless, I thought you
might enjoy seeing a photo of a lizard with a
funny looking fork tail that I caught during recent field work,
and that she sent three photo us and the lizard. Indeed,
how's this fork tail? Which is really unusual? And I'm
(16:04):
just going to assume that she did not pull the
tail off that lizard just to impress us. No, I
do not think that's it. That she writes that I
think would probably happened was that she suffered a tailbreak
the lizard she started to regenerate her tail and then
had to partial break higher up than stimulated new tail
growth from the broken part, even though the rest of
the tail is still attached. It sounds complicated, but the
pictures are well worth it. So yeah, send us send
(16:27):
us pictures of your lizard tales and various other things.
We we would love to get them. Uh. And you
have another another letter doing it? I do, I do?
I have one from an Aussie uh And Karen writes,
Hey guys, First, I'd like to say I love the
various topics you choose. I'm quite handy at quiz Nights
thanks to you. My only grip is how you pronounced
in Australian cities in terms. For instance, Geelong isn't with
(16:49):
a hard G like engulf, it's a soft G like
G that's long. Perhaps project casting you could check an
AUSEE site as to how we pronounce things. Very sorry, Karen,
we apologize and we will indeed follow up on that
aggestion in the future. Yeah, all Australian websites are blocked
on our server. I don't know what's up with that,
So if you guys want to send us an email,
(17:09):
you know where to find us. Science stuff at has
Differs dot com for more on this and thousands of
other topics. Does it how stuff works dot Com. Want
more how stuff works, check out our blogs on the
house stuff works dot com home page
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