How many times have you made a mistake and
wished you could go back and change the past? Or how often have you dreamed about what the
future might be like? The idea of time travel has been enchanting
people for generations, even though it’s usually assumed to belong only to the world
of science-fiction. But is it really as farfetched as it sounds? This is Unveiled, and today we’re uncovering
the extraordinary reality of time travel in real life. Are you a fiend for facts? Are you constantly curious? Then why not subscribe to Unveiled for more
clips like this one? And ring the bell for more fascinating content! One of the easiest ways you can accomplish
time travel is by simply looking into the night sky. Because it takes so long for a beam of light
to reach us from other parts of the universe, nothing you see in the sky is a true reflection
of reality. In fact, some of those distant stars might
not even exist anymore… in the time it has taken for their light to reach us, they could
have blossomed into spectacular supernovas or faded away completely. To look at it another way, it’s often said
that were aliens to today observe the Earth from sixty-five million lightyears away, then
they’d be able to see precisely what killed the dinosaurs - provided they had a powerful
enough telescope. While that fact doesn’t mean a great deal
to us (since we have no way of getting sixty-five million lightyears away to look back at our
own planet), we may someday see the equivalent of this mind-bending phenomenon play out somewhere
else in the universe, as the ancient precursors of a different planet roam its landscape with
us as witness. With regard to whether this truly counts as
“time travel”, however, we wouldn’t be physically going anywhere… It depends on whether you rank being able
to see into the past as a type of time travel in its own right? As far as actual movement goes, all you really
need to get to the future is speed. The faster an object is moving, the slower
it perceives time relative to a stationary object; this is time dilation. This means that if someone goes to space with
a rocket, by the time they come back to Earth they would have effectively visited the future. This phenomenon is especially well-documented…
so well-documented, in fact, that GPS systems have to account for it to stay accurate – since
the satellites they use to navigate move so quickly in orbit. Every astronaut who’s ever been to space
has been affected by the same thing, though not so much that they would notice. In 2015, the cosmonaut Gennady Padalka broke
the “time in space” record - with 879 days over multiple missions… and it’s
been said that, overall, his combined time spent moving at a higher velocity means he
moved 1/44th of a second further into the future than if he’d just stayed on Earth. This is a tiny amount, but not so tiny that
Padalka isn’t a time traveller. He has, after all, travelled 1/44th of a second
further into the future than most other people have! For all astronauts on board the International
Space Station, their tiny amount of time travel happens because the ISS is moving through
space at a speed of 17,100 miles per hour. But the ISS could never be a convenient mode
for time traveling distances of any notable length. For instance, it would take an estimated 100
years aboard it for an astronaut to go just one second into the future. The fastest manned spacecraft in history,
the Charlie Brown command module from the 1969 Apollo 10 mission, traveled at a record-breaking
24,791 miles per hour… which is quicker than the ISS, but it would still take decades
to move more than an increment into the future. Even the fastest man-made objects ever wouldn’t
stand a chance. NASA’s Parker Solar Probe exceeds speeds
of 150,000 miles per hour during its mission around the sun… Of course, there aren’t any passengers on
it, and we’re very far away from a time when a manned ship could travel at those speeds…
but, even if we could propel astronauts at 150,000 miles per hour, we’re still talking
years on board for a few seconds worth of time travel. Moving through time is no easy feat! Elsewhere, the fundamental force of gravity
can also affect time. The stronger a gravitational pull on an object
is, the slower it moves through spacetime; it’s actually another reason for the temporal
discrepancy between everyone on Earth and astronauts. It’s been proven that an atomic clock closer
to the Earth’s surface ticks slower than one that’s further away. Apply that on a larger scale and many sci-fi
creators have speculated that by utilizing the gravitational pull of a big enough object
we could provide the necessary forward momentum for a trip to the far future. The idea is that you could travel to something
exceptionally massive - a black hole, for example - orbit it for a while, and its intense
gravity would mean that by the time you left… you’d have zapped yourself into the future. Scientifically and mathematically speaking,
this almost definitely checks out, but it’s still an imperfect method for real-life time
travel. For a start, even something as massive as
a supermassive black hole might only slow you down by about fifty percent- so ten years
near a black hole might equate to twenty years for people back on Earth. Sure, a decade-long trip to move another decade
into the future shouldn’t be sniffed at… but it wouldn’t be all that practical. And the other big problem we have are the
distances at play. Say, as a means of time travel, you used the
supermassive black hole believed to be at the Milky Way’s galactic centre. It’s about 26,000 lightyears away from us…
so, if you were somehow traveling at the speed of light, it would take you 26,000 years to
get there. Upon arrival you perform your “turning ten
years into twenty” trick, and jet off back home… by the time you finally got back to
Earth, well, you’d find it more than 50,000 years into the future rather than the measly
twenty you were hoping for - thanks to sheer journey time. So, while black hole time travel is a theoretical
possibility, don’t expect to be harnessing its power any time soon. For it to work, the black hole would have
to be right next to us from the outset… but if a black hole really was that close,
it would probably have destroyed us and the solar system long before we could manipulate
it for temporal displacement. Of course, when we imagine a time machine,
we don’t just want a device that can take us to the future only - we also want the possibility
of visiting the past (or at least of returning home from the future!). Generally speaking, most theories on backward
time travel concede that it’d only be possible if we were ever able to break the speed of
light… which would break the laws of physics and is generally held to be impossible. But, are there any other ways to take a trip
to the past? The astrophysicist Ron Mallett thinks that
there are, and he’s dedicated most of his career pursuing a lifelong interest in proving
that time travel is possible. Mallett specializes in the famous theories
of Albert Einstein and has suggested a means for backward time travel which involves “twisting”
spacetime rather than needing to reach the speed of light. Mallett says that by creating a gravitational
field with a ring of lasers you could twist spacetime into a ring shape, allowing you
to travel the loop you’d made… and ultimately go to the past. If this sounds too good to be true, it’s
because there is a big catch: using Mallett’s method, you could only travel to the past
as far back as to the moment the machine itself was switched on. That means that we wouldn’t be able to zap
back in time to the dinosaurs, or miraculously prevent past events already committed to history
from happening. But such a machine would still be incredibly
useful. Any future event worth a redo could be given
one, and Mallett’s ring of lasers would make forward time travel much less risky,
as well; it would allow a traveler to the future a way to get back home, to their original
time, rather than effectively “disappearing” from the present. It should be said, though, that Mallett’s
ideas have been criticized by his colleagues, and he himself stresses that the technology
is extremely far away from becoming a reality. Finally, real-life time travel would mean
real-life time travellers, too. But, might they already be among us? While nobody attended Stephen Hawking’s
famous “party for time travellers”, plenty of people have claimed over the years that
they are from the future. One notable case was that of John Titor, who
allegedly came to the 2000s in search of an IBM 5100 computer. Titor had a compelling story but his predictions
never came true, and he’s since been written off as a complete hoax. Others have come forward to tell their story
to the press or to make cryptic blog posts and viral videos, though none have been able
to truly convince the wider public that their time traveling tales are the real deal. Nevertheless, there have been various images
of supposed time travelers that appear throughout history, as well… and some of the more unusual
likenesses have peaked public interest. For many, the fact that there are no confirmed
time travellers is enough to prove that time travel will never exist. For others, though, our tendency to be suspicious
of time travel claims means that, even if we did one day invent backward time travel,
we probably wouldn’t believe the people lucky enough to use it. For now, we can take some solace in the fact
that, ultimately, we are all traveling through time, every day… into the future at a constant
rate of one second per second. It’s not quite as glamorous as it is in
the movies, but at least there’s no real risk of us getting stuck in a far-flung future
or a land that time forgot. What do you think? Is there anything we missed? Let us know in the comments, check out these
other clips from Unveiled, and make sure you subscribe and ring the bell for our latest
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