Traveling to a far away star and getting back in time for dinner | Miguel Alcubierre | TEDxCuauhtémoc
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0:22 - 0:23I want to ask you something:
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0:23 - 0:26When was the last time
you watched the stars? -
0:26 - 0:28I know most people forget they exist
-
0:28 - 0:30specially in this polluted city
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0:30 - 0:33which is sometimes foggy,
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0:33 - 0:34we never see them.
-
0:34 - 0:36But since I was a kid,
maybe not that young, -
0:36 - 0:38maybe 12 or 13 years,
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0:38 - 0:41I've been captivated by stars
and would watch them whenever possible. -
0:41 - 0:44My dad gave me a small telescope
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0:44 - 0:47by the time I was 14 and I spent hours
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0:47 - 0:49watching planets and stars
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0:49 - 0:50and always wondering:
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0:50 - 0:52What is out there?
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0:52 - 0:55Is there someone watching me back
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0:55 - 0:57with a telescope, wondering
what is out here? -
0:58 - 1:00This allure went on for years
-
1:00 - 1:02and at some point
I decided to be an astronomer. -
1:03 - 1:06In Mexico, in order to be an astronomer
you need to be a physicist. -
1:06 - 1:08So I studied physics.
-
1:08 - 1:11I never got to be an astronomer,
now I'm something in between, -
1:11 - 1:13half an astrophysicist, half a physicist
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1:13 - 1:15but this idea of stars
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1:15 - 1:17and the possibility of reaching them
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1:17 - 1:18remained with me.
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1:19 - 1:21When I started my major in physics
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1:21 - 1:23I realized something many of you
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1:23 - 1:26have heard of, even if you are not
totally clear about it: -
1:27 - 1:31that more than 100 years ago, in 1905,
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1:31 - 1:32this guy named Albert Einstein,
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1:32 - 1:35discovered that light speed
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1:35 - 1:38is the fastest in the universe.
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1:38 - 1:39That might not say you a lot
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1:39 - 1:41because light speed is huge.
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1:41 - 1:45Light moves up to 186,000 mi/s
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1:45 - 1:48so high a speed that we can phone call
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1:48 - 1:50someone in India or Japan
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1:50 - 1:52with no problem at all.
-
1:52 - 1:56Even astronauts who went
to the moon 40 years ago -
1:57 - 2:01were interviewed and
the President could talk to them -
2:01 - 2:04with no evident delay
-
2:04 - 2:06even though the astronauts
were in the moon, -
2:06 - 2:09thing is that light speed is huge
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2:09 - 2:13and the universe gigantic.
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2:14 - 2:16We cannot travel faster than light speed
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2:16 - 2:18and that is a severe problem
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2:18 - 2:21to reach for the stars.
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2:21 - 2:23Sun is 8 light-minutes away,
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2:23 - 2:26that is, it takes 8 minutes for light
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2:26 - 2:28to get here from the Sun,
from the Sun to us. -
2:28 - 2:30If the Sun exploded right now,
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2:30 - 2:32nobody would notice
up until eight minutes later. -
2:33 - 2:36The closest star after the Sun
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2:36 - 2:38is Alfa Centauri,
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2:38 - 2:40it takes four years for light to travel
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2:40 - 2:42and it's right besides the Sun.
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2:42 - 2:43We live in a galaxy
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2:43 - 2:46that is a star spiral called Milky Way.
-
2:46 - 2:50The center of our galaxy
was 30,000 light years away, -
2:50 - 2:52it takes 30,000 light years
for light to travel -
2:52 - 2:55from the center of the galaxy to us,
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2:55 - 2:57and two million years
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2:57 - 2:58in traveling from Andromeda galaxy
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2:58 - 3:01that is one of our neighbor galaxies.
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3:02 - 3:04The universe is huge, vast,
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3:04 - 3:07if we ever want to reach the stars
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3:07 - 3:10the light limit is very serious,
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3:10 - 3:12a very serious problem, but why?
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3:13 - 3:15Why we cannot travel faster than light?
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3:15 - 3:17And it's not because Einstein said so,
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3:17 - 3:19that is no how science works.
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3:19 - 3:21In science
there is no authority principle; -
3:21 - 3:23it's not because some famous guy says so.
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3:24 - 3:26There are reasons, theoretical reasons,
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3:26 - 3:28observational reasons,
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3:28 - 3:29experiments show it,
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3:29 - 3:33it is a verified fact,
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3:33 - 3:34but why?
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3:34 - 3:38Basically, the answer is that
theory of relativity prevents it, -
3:38 - 3:40so I will tell you a bit,
-
3:40 - 3:42a very quick course:
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3:42 - 3:46Relativity in a couple of minutes.
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3:46 - 3:49Don't be afraid,
I'll give a general overview, -
3:49 - 3:52normally it takes six months to teach this
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3:52 - 3:55to sixth and seventh graders
of physics major. -
3:55 - 3:57So right now I will explain it
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3:57 - 3:59in two minutes and for non-physicists.
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3:59 - 4:01So, don't worry.
-
4:03 - 4:05Relativity is an old concept
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4:05 - 4:07though it wasn't called like that.
-
4:07 - 4:11The concept can be traced
back from Galileo Galilei -
4:11 - 4:14around 1620, in the 17th century.
-
4:15 - 4:18Galileo was the first one
to realize something interesting, -
4:18 - 4:20when it comes to movement, when I move,
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4:20 - 4:23my movement is always relative
to something else. -
4:23 - 4:25Movement is said to be relative,
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4:25 - 4:29here on the stage,
my movement is relative to the floor. -
4:29 - 4:32The measurement of your car speed
is relative to the street, -
4:33 - 4:35actually planes speed measurement
-
4:35 - 4:38is made relative to the air,
not the floor. -
4:38 - 4:40You might have noticed this
while watching a movie. -
4:40 - 4:43A plane speed measurement
is relative to the air, -
4:43 - 4:46and the Earth spins around the Sun, etc.
-
4:46 - 4:48If you were somewhere in space
-
4:48 - 4:52in the middle of nowhere
it would be useless -
4:52 - 4:54to ask if you are moving or not
-
4:54 - 4:58because there is no reference
to compare your position, -
4:58 - 5:00so movement is relative,
speeds are relative, -
5:00 - 5:03because they are always measured
in relation to something else. -
5:03 - 5:06This was discovered
by Galileo 400 years ago. -
5:06 - 5:08That was an interesting fact
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5:08 - 5:11for all physic studies made after Galileo.
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5:11 - 5:15Newton and all great advances
of the 18th and 19th centuries -
5:15 - 5:17agreed with Galileo.
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5:17 - 5:20Speed is relative, that's fine,
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5:20 - 5:22speeds aren't absolute.
-
5:22 - 5:25But by the end of 19th century
something strange happened, -
5:25 - 5:28many physicists studying light
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5:28 - 5:31discovered that light is quite weird,
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5:31 - 5:34light speed is indeed absolute
-
5:34 - 5:36and though Galileo stated
that speeds were relative, -
5:36 - 5:39that's not the case of light,
it's always the same number -
5:39 - 5:40no matter who measures it,
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5:40 - 5:43or how fast is going whoever is measuring,
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5:43 - 5:47no matter how fast the lightbulb
sending out the light is moving. -
5:47 - 5:49The measurement always
yields the same number -
5:49 - 5:51and this was a problem.
-
5:51 - 5:53This might not seem interesting to you
-
5:53 - 5:57but physicists of the 19th
century were going crazy. -
5:57 - 6:01Problem was: either Galileo was wrong
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6:01 - 6:03and speeds were indeed absolute,
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6:03 - 6:05which was apparently nonsense;
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6:05 - 6:07or those who were measuring light speed
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6:07 - 6:09were wrong and didn't know how to measure.
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6:09 - 6:11But nobody was wrong
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6:11 - 6:13which was even worst.
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6:13 - 6:17Decades went by,
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6:17 - 6:20until in 1905 this guy appeared,
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6:20 - 6:22a man called Albert Einstein,
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6:22 - 6:25who devoted his life to bringing together
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6:25 - 6:28Galileo's idea that speeds were relative
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6:28 - 6:31and the apparently real fact
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6:31 - 6:34shown by the experiments,
that there was an absolute speed, -
6:34 - 6:36light speed.
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6:36 - 6:38Long story short,
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6:38 - 6:40because math is complicated,
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6:40 - 6:41part of Einstein genius
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6:41 - 6:44was realizing there was a solution.
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6:45 - 6:47There was a logical solution
to the problem -
6:48 - 6:51and that logical solution
derived in what we now know -
6:51 - 6:54as Einstein's theory of relativity.
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6:54 - 6:57It's a very interesting theory
that changes -
6:57 - 6:59what we understand by space and time,
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6:59 - 7:02for instance, nobody tells us
that space is relative -
7:02 - 7:05distances, object lengths
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7:05 - 7:08depend on their movement;
if an object moves fast, they shrink. -
7:08 - 7:10Time is also relative,
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7:10 - 7:13any watch ticking relative
to my movement, would delay -
7:13 - 7:15this we have measured many times,
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7:15 - 7:19even worst: simultaneity is relative;
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7:19 - 7:22when I say two things
happen exactly at once, -
7:22 - 7:24someone moving in relation to me
would disagree. -
7:25 - 7:28One of us sees something first
and worst: -
7:28 - 7:30we might be moving on opposed directions
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7:30 - 7:31and watch things backwards:
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7:31 - 7:33first this one, then that one.
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7:33 - 7:35So the conclusion is that sometimes,
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7:35 - 7:38the order in time of different things
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7:38 - 7:40is not absolute, the order
of time can change, -
7:40 - 7:43one thing before, other thing after
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7:43 - 7:45but this brings up another huge problem,
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7:45 - 7:48if time order is not well defined,
what about causality? -
7:48 - 7:50If something causes something else
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7:50 - 7:52that something should had happened first,
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7:52 - 7:55but if we disagree on what happened first,
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7:55 - 7:58where does that leaves causality?
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7:58 - 8:00Another crisis.
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8:00 - 8:02Part of what Einstein did
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8:02 - 8:04was realizing that there was solution,
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8:04 - 8:07a solution to protect causality
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8:07 - 8:10was thinking that light speed
is not absolute, -
8:10 - 8:15but the maximum speed of universe.
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8:15 - 8:18If nothing can travel faster than light
we protect causality. -
8:19 - 8:21If something could travel
faster than light -
8:21 - 8:24then we could travel to the past,
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8:24 - 8:28we would be able to see
the effect before the cause, -
8:28 - 8:30which is not the proper way.
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8:30 - 8:33So light speed is the maximum speed
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8:33 - 8:35and that is to protect causality.
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8:35 - 8:39So far as of the beginning
of the 20th century, -
8:39 - 8:40light speed was the fastest
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8:40 - 8:43and if that was all left to say,
my talk would be done -
8:43 - 8:45and off we go.
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8:45 - 8:47But, fortunately that's not the case.
-
8:47 - 8:50In 1916, Einstein developed
a second theory, -
8:50 - 8:53also called relativity and that's
why people get confused -
8:53 - 8:55this one is called general relativity,
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8:55 - 8:57and it's a theory about gravity.
-
8:57 - 8:59Einstein tried to understand gravity,
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8:59 - 9:01which we already understood
a bit since Newton; -
9:01 - 9:03but he noticed some problems,
-
9:03 - 9:07gravity was thought of
by Newton as instantaneous, -
9:07 - 9:10if someone moved the Sun,
Earth would immediately react, -
9:10 - 9:14this would go against the fact that
nothing can travel faster than light, -
9:14 - 9:18so Einstein began to develop
a new gravity theory, -
9:18 - 9:19it took him 10 years,
-
9:19 - 9:23an amazing achievement
for someone as smart of Einstein, -
9:23 - 9:24was based on a beautiful thing:
-
9:24 - 9:27the Equivalence Principle,
also discovered by Galileo: -
9:27 - 9:30all objects fall at the same speed
-
9:30 - 9:33if two things were dropped at once,
they would fall at the same time, -
9:33 - 9:37a bowling ball or a ping pong ball
would fall just the same, -
9:37 - 9:40the heavier one does not fall faster,
in case you were wondering. -
9:40 - 9:42That means, from another point of view,
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9:42 - 9:47that the trajectory of an object
when there is gravity, -
9:47 - 9:49does not depend on the object.
-
9:49 - 9:51All objects follow the same trajectory
-
9:51 - 9:54curved trajectories, you've seen that,
-
9:54 - 9:57I throw objects and they move
in parables and ellipses -
9:57 - 10:01but if those trajectories are curve
and nondependent of the object -
10:01 - 10:04then trajectory is a property of space,
but they are curve, -
10:04 - 10:06then space must be curve.
-
10:06 - 10:07Einstein concluded
-
10:07 - 10:10that gravity is a space deformation.
-
10:10 - 10:12An interesting and beautiful thing,
-
10:12 - 10:15and what is beautiful about it
is that I can cheat, -
10:15 - 10:18I can use space deformation
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10:18 - 10:19to cheat on Einstein himself,
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10:19 - 10:22so I use Einstein to cheat on Einstein.
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10:22 - 10:25I can imagine ways to distort space
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10:26 - 10:29to work around the statement
"nothing can go faster than light" -
10:29 - 10:32and, technically, I could
reach a faraway star -
10:32 - 10:35and then come back in time for dinner.
-
10:35 - 10:38I will share with you two possibilities,
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10:38 - 10:41that are allowed on Einstein theory,
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10:41 - 10:43one is beautiful
-
10:43 - 10:46and its technical name
is Einstein-Rosen bridge, -
10:46 - 10:49sounds technical because Einstein
-
10:49 - 10:51and another scientist called Rosen
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10:51 - 10:54had this idea in 1935.
-
10:54 - 10:57But in literature and on sci-fi movies
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10:57 - 10:59it is called a Wormhole.
-
10:59 - 11:02If you like science fiction
then you might have seen it recently, -
11:02 - 11:04in the movie Interstellar.
-
11:04 - 11:08On the movie, they travel
through a wormhole. -
11:08 - 11:10A wormhole is like a tunnel,
-
11:10 - 11:14I enter here and I end up
in Alpha Centauri, -
11:14 - 11:16but traveling a shorter distance,
-
11:16 - 11:18like a shortcut in space.
-
11:18 - 11:19These structures --
-
11:19 - 11:23here is a beautiful diagram
of a wormhole in two dimensions -- -
11:23 - 11:26are allowed by the Einstein's theory,
-
11:26 - 11:29because this theory allows these tunnels,
-
11:29 - 11:31one thing is that the theory allows it
-
11:31 - 11:33and another is having
an idea of how to do that. -
11:33 - 11:36Nobody knows how to make a wormhole,
-
11:36 - 11:39but at least theory allows it.
-
11:39 - 11:42Another idea,
and I'll let you think about it, -
11:42 - 11:45another idea is that it is not necessary
to make holes in space, -
11:45 - 11:48an idea that thought by some guy
not so long ago, -
11:48 - 11:51in 1994, this guy on the picture,
-
11:52 - 11:55and the idea is different;
instead of making holes in space -
11:55 - 11:57let's use another property of space.
-
11:57 - 12:02Space can bended, twisted and expanded,
-
12:02 - 12:05maybe you heard about
how universe expands, -
12:05 - 12:07galaxies move away from one another
-
12:07 - 12:11not because they are
drifting away from a center -
12:11 - 12:13where an explosion occurred, no.
-
12:13 - 12:16The way we understand it in physics
is that galaxies are still, -
12:16 - 12:20and what is growing bigger is space;
space is expanding. -
12:21 - 12:23So I can use this idea in a small scale.
-
12:24 - 12:27Imagine I'm standing here and somehow
-
12:27 - 12:29I can expand the space behind me.
-
12:29 - 12:31I would start to drift away
from that wall, -
12:31 - 12:34and if at the same time
I shrink the space in front of me -
12:34 - 12:36I would become closer
to the wall in front of me. -
12:36 - 12:39If I combine
the expansion and contraction, -
12:39 - 12:42I could move from here
to that wall without moving, -
12:42 - 12:44because the space made all the moving.
-
12:44 - 12:48This is called warp drive
or drive through distortion -
12:49 - 12:52and it's another way
to travel faster than light, -
12:52 - 12:54actually you could travel
as fast as you wish. -
12:54 - 12:58These are two ideas on how
we could travel faster than light. -
12:59 - 13:01But there is a price to pay.
-
13:01 - 13:04Such is life, whenever
you find something cool -
13:04 - 13:06it's too expensive.
-
13:06 - 13:08We have a similar case here:
-
13:09 - 13:11from those two ideas,
-
13:11 - 13:14both worm holes and warp propulsion
-
13:14 - 13:16require, whenever we do
the math of something -
13:16 - 13:19called negative energy, which might
not be crystal clear for you, -
13:19 - 13:22but remember what Einstein said:
-
13:22 - 13:24"mass and energy are equivalent",
the same thing. -
13:24 - 13:27Remember nuclear reactors
and atomic bombs, -
13:27 - 13:29mass and energy are the same.
-
13:29 - 13:33So negative energy equals negative mass,
-
13:33 - 13:37and I'd never went to buy
minus 9 pounds of tortilla. -
13:38 - 13:40There are no negative masses,
-
13:40 - 13:43without negative masses
there are no negative energies -
13:43 - 13:46and without negative energies
none of this is possible, -
13:46 - 13:48No holes in space-time,
-
13:48 - 13:50no warp propulsion,
-
13:50 - 13:52and that's a problem.
-
13:52 - 13:54Negative energy is not forbidden,
-
13:54 - 13:56physics laws don't forbid it,
-
13:56 - 13:58but we've never seen it.
-
13:58 - 14:01It's one of those things
that simply do not exist. -
14:01 - 14:05So, with this initial question:
-
14:05 - 14:07Can we travel faster than light?
-
14:07 - 14:10will we someday travel the stars
and get back in time for dinner? -
14:10 - 14:13In 1905 Einstein told us
it was not possible, -
14:13 - 14:15that light speed was a limit,
-
14:15 - 14:18but sometimes,
using Einstein's other theory, -
14:18 - 14:21general relativity, we can cheat
and bend the space, -
14:21 - 14:23expand it, compress it, make holes on it,
-
14:23 - 14:26and travel faster than light,
-
14:26 - 14:27however, the price of it
-
14:27 - 14:30is finding energies or negative masses,
-
14:30 - 14:32though they might not exist.
-
14:32 - 14:33So we are a bit stuck,
-
14:33 - 14:37but such is science
and that's part of my message, -
14:37 - 14:39science moves forward by making questions,
-
14:39 - 14:42and sometimes we find answers,
-
14:42 - 14:45sometimes we find answers we don't like,
-
14:45 - 14:48that aren't what we wanted,
but universe is not how we want it. -
14:48 - 14:50It is what it is and we
sometimes find out -
14:50 - 14:53that we don't have enough information,
-
14:53 - 14:55to answer the question,
-
14:55 - 14:57and that is our current situation.
-
14:57 - 14:59Currently, we do not have
all the information. -
14:59 - 15:03Luckily, in 20, 30 or 100 years
someone will come -
15:03 - 15:06and find the answer and tell us for once
-
15:06 - 15:09if we can reach the stars
faster than light speed. -
15:09 - 15:12Before I go I will ask you
to do something, -
15:12 - 15:16tonight, if clouds allow it, please go out
-
15:16 - 15:18and take a look of the stars
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15:18 - 15:20and think, what is out there?
-
15:20 - 15:21Thank you so much.
-
15:21 - 15:23(Applause)
- Title:
- Traveling to a far away star and getting back in time for dinner | Miguel Alcubierre | TEDxCuauhtémoc
- Description:
-
Miguel uses all his knowledge and wit to explain us the theory behind traveling faster than light-speed.
Theoretical physicist, after studying in Mexico and the UK, he describes new mathematical models to describe the physics of black holes. He is the current director of UNAM Nuclear Sciences Institute.
This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at https://www.ted.com/tedx
- Video Language:
- Spanish
- Team:
- closed TED
- Project:
- TEDxTalks
- Duration:
- 15:37