[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:06.86,0:00:09.44,Default,,0000,0000,0000,,Have you ever daydreamed\Nabout traveling through time,
Dialogue: 0,0:00:09.46,0:00:13.12,Default,,0000,0000,0000,,perhaps fast forward in the centuries\Nand seeing the distant future?
Dialogue: 0,0:00:13.14,0:00:15.18,Default,,0000,0000,0000,,Well, time travel is possible,
Dialogue: 0,0:00:15.21,0:00:17.64,Default,,0000,0000,0000,,and what's more, it's already been done.
Dialogue: 0,0:00:17.66,0:00:18.93,Default,,0000,0000,0000,,Meet Sergei Krikalev,
Dialogue: 0,0:00:18.96,0:00:21.73,Default,,0000,0000,0000,,the greatest time traveler\Nin human history.
Dialogue: 0,0:00:21.75,0:00:23.76,Default,,0000,0000,0000,,This Russian cosmonaut holds the record
Dialogue: 0,0:00:23.79,0:00:26.35,Default,,0000,0000,0000,,for the most amount of time\Nspent orbiting our planet,
Dialogue: 0,0:00:26.37,0:00:30.06,Default,,0000,0000,0000,,a total of 803 days,\N9 hours, and 39 minutes.
Dialogue: 0,0:00:31.14,0:00:32.46,Default,,0000,0000,0000,,During his stay in space,
Dialogue: 0,0:00:32.48,0:00:34.36,Default,,0000,0000,0000,,he time traveled into his own future
Dialogue: 0,0:00:34.38,0:00:36.52,Default,,0000,0000,0000,,by 0.02 seconds.
Dialogue: 0,0:00:37.92,0:00:40.44,Default,,0000,0000,0000,,Traveling at 17,500 miles an hour,
Dialogue: 0,0:00:40.46,0:00:43.46,Default,,0000,0000,0000,,he experienced an effect\Nknown as time dilation,
Dialogue: 0,0:00:43.48,0:00:45.09,Default,,0000,0000,0000,,and one day the same effect
Dialogue: 0,0:00:45.11,0:00:48.39,Default,,0000,0000,0000,,might make significant time travel\Nto the future commonplace.
Dialogue: 0,0:00:49.58,0:00:52.85,Default,,0000,0000,0000,,To see why moving faster through space\Naffects passage of time,
Dialogue: 0,0:00:52.88,0:00:55.01,Default,,0000,0000,0000,,we need to go back to the 1880s,
Dialogue: 0,0:00:55.03,0:00:56.41,Default,,0000,0000,0000,,when two American scientists,
Dialogue: 0,0:00:56.44,0:00:58.34,Default,,0000,0000,0000,,Albert Michelson and Edward Morley,
Dialogue: 0,0:00:58.37,0:01:01.78,Default,,0000,0000,0000,,were trying to measure the effect\Nof the Earth's movement around the Sun
Dialogue: 0,0:01:01.80,0:01:03.10,Default,,0000,0000,0000,,on the speed of light.
Dialogue: 0,0:01:03.12,0:01:06.27,Default,,0000,0000,0000,,When a beam of light was moving\Nin the same direction as the Earth,
Dialogue: 0,0:01:06.29,0:01:08.26,Default,,0000,0000,0000,,they expected the light to travel faster.
Dialogue: 0,0:01:08.29,0:01:10.92,Default,,0000,0000,0000,,And when the Earth was moving\Nin the opposite direction,
Dialogue: 0,0:01:10.94,0:01:12.87,Default,,0000,0000,0000,,they expected it to go slower.
Dialogue: 0,0:01:12.90,0:01:14.86,Default,,0000,0000,0000,,But they found something very curious.
Dialogue: 0,0:01:14.88,0:01:18.38,Default,,0000,0000,0000,,The speed of light remained the same\Nno matter what the Earth was doing.
Dialogue: 0,0:01:18.40,0:01:20.64,Default,,0000,0000,0000,,Two decades later,\NAlbert Einstein was thinking
Dialogue: 0,0:01:20.67,0:01:23.96,Default,,0000,0000,0000,,about the consequences\Nof that never-changing speed of light.
Dialogue: 0,0:01:23.98,0:01:25.32,Default,,0000,0000,0000,,And it was his conclusions,
Dialogue: 0,0:01:25.34,0:01:27.92,Default,,0000,0000,0000,,formulated in the theory\Nof special relativity,
Dialogue: 0,0:01:27.95,0:01:30.76,Default,,0000,0000,0000,,that opened the door\Ninto the world of time travel.
Dialogue: 0,0:01:30.79,0:01:32.52,Default,,0000,0000,0000,,Imagine a man named Jack,
Dialogue: 0,0:01:32.54,0:01:34.56,Default,,0000,0000,0000,,standing in the middle\Nof a train carriage,
Dialogue: 0,0:01:34.59,0:01:36.23,Default,,0000,0000,0000,,traveling at a steady speed.
Dialogue: 0,0:01:36.26,0:01:38.96,Default,,0000,0000,0000,,Jack's bored and starts bouncing\Na ball up and down.
Dialogue: 0,0:01:38.99,0:01:42.04,Default,,0000,0000,0000,,What would Jill, standing on the platform,\Nsee through the window
Dialogue: 0,0:01:42.06,0:01:43.60,Default,,0000,0000,0000,,as the train whistles through?
Dialogue: 0,0:01:43.63,0:01:46.57,Default,,0000,0000,0000,,Well, between Jack dropping the ball\Nand catching it again,
Dialogue: 0,0:01:46.59,0:01:49.65,Default,,0000,0000,0000,,Jill would have seen him move\Nslightly further down the track,
Dialogue: 0,0:01:49.68,0:01:52.50,Default,,0000,0000,0000,,resulting in her seeing the ball\Nfollow a triangular path.
Dialogue: 0,0:01:53.41,0:01:56.18,Default,,0000,0000,0000,,This means Jill sees the ball\Ntravel further than Jack does
Dialogue: 0,0:01:56.21,0:01:58.08,Default,,0000,0000,0000,,in the same time period.
Dialogue: 0,0:01:58.10,0:02:00.29,Default,,0000,0000,0000,,And because speed\Nis distance divided by time,
Dialogue: 0,0:02:00.32,0:02:02.84,Default,,0000,0000,0000,,Jill actually sees the ball move faster.
Dialogue: 0,0:02:03.83,0:02:06.71,Default,,0000,0000,0000,,But what if Jack's bouncing ball\Nis replaced with two mirrors
Dialogue: 0,0:02:06.74,0:02:08.83,Default,,0000,0000,0000,,which bounce a beam of light between them?
Dialogue: 0,0:02:08.85,0:02:11.08,Default,,0000,0000,0000,,Jack still sees the beam dropping down
Dialogue: 0,0:02:11.11,0:02:14.29,Default,,0000,0000,0000,,and Jill still sees the light beam\Ntravel a longer distance,
Dialogue: 0,0:02:14.31,0:02:17.42,Default,,0000,0000,0000,,except this time Jack and Jill\Ncannot disagree on the speed
Dialogue: 0,0:02:17.45,0:02:20.60,Default,,0000,0000,0000,,because the speed of light\Nremains the same no matter what.
Dialogue: 0,0:02:21.54,0:02:24.46,Default,,0000,0000,0000,,And if the speed is the same\Nwhile the distance is different,
Dialogue: 0,0:02:24.49,0:02:26.100,Default,,0000,0000,0000,,this means the time taken\Nwill be different as well.
Dialogue: 0,0:02:27.91,0:02:32.16,Default,,0000,0000,0000,,Thus, time must tick at different rates\Nfor people moving relative to each other.
Dialogue: 0,0:02:32.19,0:02:34.81,Default,,0000,0000,0000,,Imagine that Jack and Jill\Nhave highly accurate watches
Dialogue: 0,0:02:34.83,0:02:38.02,Default,,0000,0000,0000,,that they synchronize\Nbefore Jack boards the train.
Dialogue: 0,0:02:38.04,0:02:40.43,Default,,0000,0000,0000,,During the experiment,\NJack and Jill would each see
Dialogue: 0,0:02:40.45,0:02:42.07,Default,,0000,0000,0000,,their own watch ticking normally.
Dialogue: 0,0:02:43.05,0:02:46.14,Default,,0000,0000,0000,,But if they meet up again later\Nto compare watches,
Dialogue: 0,0:02:46.16,0:02:48.33,Default,,0000,0000,0000,,less time would have\Nelapsed on Jack's watch,
Dialogue: 0,0:02:48.35,0:02:51.56,Default,,0000,0000,0000,,balancing the fact that Jill saw\Nthe light move further.
Dialogue: 0,0:02:52.39,0:02:54.05,Default,,0000,0000,0000,,This idea may sound crazy,
Dialogue: 0,0:02:54.08,0:02:56.10,Default,,0000,0000,0000,,but like any good scientific theory,
Dialogue: 0,0:02:56.13,0:02:57.13,Default,,0000,0000,0000,,it can be tested.
Dialogue: 0,0:02:58.05,0:03:00.44,Default,,0000,0000,0000,,In the 1970s, scientists boarded a plane
Dialogue: 0,0:03:00.46,0:03:02.52,Default,,0000,0000,0000,,with some super-accurate atomic clocks
Dialogue: 0,0:03:02.54,0:03:05.32,Default,,0000,0000,0000,,that were synchronized\Nwith some others left on the ground.
Dialogue: 0,0:03:06.19,0:03:08.24,Default,,0000,0000,0000,,After the plane had\Nflown around the world,
Dialogue: 0,0:03:08.26,0:03:10.26,Default,,0000,0000,0000,,the clocks on board\Nshowed a different time
Dialogue: 0,0:03:10.28,0:03:11.58,Default,,0000,0000,0000,,from those left behind.
Dialogue: 0,0:03:12.52,0:03:14.73,Default,,0000,0000,0000,,Of course, at the speed\Nof trains and planes,
Dialogue: 0,0:03:14.75,0:03:16.20,Default,,0000,0000,0000,,the effect is minuscule.
Dialogue: 0,0:03:16.22,0:03:18.56,Default,,0000,0000,0000,,But the faster you go,\Nthe more time dilates.
Dialogue: 0,0:03:18.58,0:03:21.15,Default,,0000,0000,0000,,For astronauts orbiting\Nthe Earth for 800 days,
Dialogue: 0,0:03:21.18,0:03:22.74,Default,,0000,0000,0000,,it starts to add up.
Dialogue: 0,0:03:22.76,0:03:25.54,Default,,0000,0000,0000,,But what affects humans\Nalso affects machines.
Dialogue: 0,0:03:25.57,0:03:27.72,Default,,0000,0000,0000,,Satellites of the global\Npositioning system
Dialogue: 0,0:03:27.74,0:03:29.38,Default,,0000,0000,0000,,are also hurdling around the Earth
Dialogue: 0,0:03:29.41,0:03:30.89,Default,,0000,0000,0000,,at thousands of miles an hour.
Dialogue: 0,0:03:30.92,0:03:33.24,Default,,0000,0000,0000,,So, time dilation kicks in here, too.
Dialogue: 0,0:03:34.29,0:03:36.98,Default,,0000,0000,0000,,In fact, their speed causes\Nthe atomic clocks on board
Dialogue: 0,0:03:37.00,0:03:38.76,Default,,0000,0000,0000,,to disagree with clocks on the ground
Dialogue: 0,0:03:38.79,0:03:40.81,Default,,0000,0000,0000,,by seven millionths of a second daily.
Dialogue: 0,0:03:40.83,0:03:42.27,Default,,0000,0000,0000,,Left uncorrected,
Dialogue: 0,0:03:42.29,0:03:44.12,Default,,0000,0000,0000,,this would cause GPS to lose accuracy
Dialogue: 0,0:03:44.14,0:03:45.99,Default,,0000,0000,0000,,by a few kilometers each day.
Dialogue: 0,0:03:47.59,0:03:49.97,Default,,0000,0000,0000,,So, what does all this have\Nto do with time travel
Dialogue: 0,0:03:49.99,0:03:51.76,Default,,0000,0000,0000,,to the far, distant future?
Dialogue: 0,0:03:51.78,0:03:55.14,Default,,0000,0000,0000,,Well, the faster you go,\Nthe greater the effect of time dilation.
Dialogue: 0,0:03:55.16,0:03:56.69,Default,,0000,0000,0000,,If you could travel really close
Dialogue: 0,0:03:56.71,0:04:00.77,Default,,0000,0000,0000,,to the speed of light, say 99.9999%,
Dialogue: 0,0:04:00.79,0:04:02.17,Default,,0000,0000,0000,,on a round-trip through space
Dialogue: 0,0:04:02.20,0:04:04.70,Default,,0000,0000,0000,,for what seemed to you like ten years,
Dialogue: 0,0:04:04.72,0:04:06.15,Default,,0000,0000,0000,,you'd actually return to Earth
Dialogue: 0,0:04:06.18,0:04:08.40,Default,,0000,0000,0000,,around the year 9000.
Dialogue: 0,0:04:08.43,0:04:10.55,Default,,0000,0000,0000,,Who knows what you'd see\Nwhen you returned?!
Dialogue: 0,0:04:10.58,0:04:12.22,Default,,0000,0000,0000,,Humanity merged with machines,
Dialogue: 0,0:04:12.25,0:04:15.31,Default,,0000,0000,0000,,extinct due to climate change\Nor asteroid impact,
Dialogue: 0,0:04:15.33,0:04:17.72,Default,,0000,0000,0000,,or inhabiting a permanent colony on Mars.
Dialogue: 0,0:04:18.95,0:04:19.99,Default,,0000,0000,0000,,But the trouble is,
Dialogue: 0,0:04:20.01,0:04:22.89,Default,,0000,0000,0000,,getting heavy things like people,\Nnot to mention space ships,
Dialogue: 0,0:04:22.92,0:04:26.60,Default,,0000,0000,0000,,up to such speeds requires\Nunimaginable amounts of energy.
Dialogue: 0,0:04:26.63,0:04:29.35,Default,,0000,0000,0000,,It already takes enormous\Nparticle accelerators
Dialogue: 0,0:04:29.37,0:04:30.89,Default,,0000,0000,0000,,like the Large Hadron Collider
Dialogue: 0,0:04:30.92,0:04:34.58,Default,,0000,0000,0000,,to accelerate tiny subatomic particles\Nto close to light speed.
Dialogue: 0,0:04:35.48,0:04:39.49,Default,,0000,0000,0000,,But one day, if we can develop the tools\Nto accelerate ourselves to similar speeds,
Dialogue: 0,0:04:39.51,0:04:41.47,Default,,0000,0000,0000,,then we may regularly send time travelers
Dialogue: 0,0:04:41.49,0:04:42.53,Default,,0000,0000,0000,,into the future,
Dialogue: 0,0:04:42.55,0:04:45.08,Default,,0000,0000,0000,,bringing with them tales\Nof a long, forgotten past.