The possibility of time travel is often debated
and theorized by laymen, but it has also garnered
the attention of the titans of physics.
Ever since Albert Einstein demonstrated that
time dilation is a real thing, speculation
has grown about the possibilities of time
travel.
Einstein’s work illustrated that the faster
someone travels, and the closer they get to
light speed, the slower time moves for that
individual.
All the while, time continues to move at the
same pace for people on Earth.
Stephen Hawking, the world renowned theoretical
physicist, did not shy away from the growing
speculation about time travel.
10.
Champagne Party
Let’s just say Stephen Hawking was a skeptic
when it comes to traveling back in time.
To make his point, he conducted a simple,
but elegant experiment.
He held a party.
That’s right, in 2009, Hawking decided to
host a party with balloons, hors d’oeuvres,
and champagne for guests willing to travel
back in time for the party.
Hawking told reporters, “I gave a party
for time-travelers, but I didn’t send out
the invitations until after the party.
I sat there a long time, but no one came.”
The Discovery Channel was there to capture
the event at the University of Cambridge,
in the event that someone happened to arrive.
Hawking even made sure to provide precise
GPS coordinates, just in case someone became
lost through space time.
9.
Time Machines
Although Hawking was immensely skeptical of
the possibility about traveling back in time,
he was willing to engage in the notion.
According to Mr. Hawking, everything including
time itself has wrinkles and voids in it;
there are tiny tunnels in the quantum world
that form, disappear, and reappear.
Theoretically, they would link separate places
and, most importantly for time travelers,
time.
However, these wrinkles and voids on the quantum
level are far too small for a human to pass
through.
A time machine that wanted to attempt such
a feat would need to capture and enlarge a
wormhole enough so that a spaceship could
travel through it.
If such a device were to built, Hawking said,
“One end could be here near Earth, and the
other far, far away, near some distant planet.”
8.
Time Travel into the Past May Be Impossible
After his theorizations, Hawking concluded
that traveling back in time is probably impossible.
He believed that the wormhole would create
paradoxes that would prevent it from being
created in the first place.
For example, a person traveling back in time
and killing themselves before the creation
of the time machine.
More importantly, Hawking argued that natural
radiation would seep into the wormhole and
the resulting feedback would be so strong
that the wormhole, and thus the time machine,
would be destroyed.
He went even further, suggesting that the
creation of such a device may have dire effects.
Hawking believed it may trigger a bolt of
radiation that would not only destroy the
time traveling spaceship, but space time itself.
7.
Traveling into the Future
Although Hawking didn’t believing traveling
back in time is possible, he did believe that
traveling into the future is possible.
An example he cites is the Earth’s mass
dragging on time.
If the Earth was approaching a black hole,
time would slow down for people and the force
of gravity would increase.
Naturally, a black hole is a dangerous method
so Hawking proposed the potential of traveling
near the speed of light.
As one nears the speed of light, Hawking argued,
time would slow down in order to protect the
speed, and also to make it physically impossible
to ever break it.
Therefore, Hawking believed, “that a human
traveling near the speed of light could reach
the end of the galaxy within their lifetime.”
6.
The Spaceship
The fastest manned spaceship was the Apollo
10, and it climbed to a speed of 25,000 mph.
In order for time travel to be possible, humans
would have to design a spaceship that travels
2,000 times the speed of the Apollo 10.
That’s… that’s pretty fast, you guys.
It will also need absurd amounts of fuel to
make it through a wormhole while not sacrificing
any of its speed.
It’s unlikely that even Elon Musk will be
able to accomplish this feat in the coming
years, but someday it’s certainly a possibility.
5.
Paradoxes
Hawking came up with his own paradox named
the “Mad Scientist” paradox to further
describe the unlikely possibility of traveling
into the past.
He assured us that he didn’t like the stereotype
that scientists are “mad,” but in this
case he agrees that the misconception is real.
Suppose that this scientist created a device
that would allow himself to travel just one
minute into the past, witnessing his alternate
self.
What would stop this mad scientist from killing
his earlier self?
Hawking argued that the mere possibility invalidates
the fundamental principle of the universe
that cause happens before effects.
Hawking said, “I think something will always
happen that prevents the paradox.
Somehow there must be a reason why our scientist
will never find himself in a situation where
he could shoot himself.”
4.
Global Positioning System
Unlike many of his colleagues, Hawking firmly
believed that time travel into the future
is possible.
Hawking noted that Albert Einstein was the
first to fully grasp the concept of time and
prove that there are places where time slows
down and others where it speeds up.
As a result of Einstein’s work, Hawking
was convinced that traveling into the future
was possible.
Hawking suggests that a fuller understanding
of Global Positioning System (GPS) is all
the proof necessary to conclude that future
time travel is possible.
A network of satellites orbiting around the
Earth make satellite navigation possible.
They’ve also revealed that time runs faster
in space than on Earth.
The satellites contain very precise clocks
and yet, “they all gain around a third of
a billionth of a second every day.”
The system has to correct for the drift, otherwise
that tiny difference would upset the whole
system, causing every GPS device on Earth
to decrease in accuracy by about six miles
a day.
Some might suggest that the problem lies with
the clocks, but the truth is that they run
fast because time itself runs faster in space
than on the blue planet below.
The Earth’s mass literally drags on time,
slowing it down like a stretch in a river.
Einstein understood this better than anyone,
and Hawking believed that his scientific predecessor
proved that time travel into the future is
possible.
3.
Future Travel Transportation System
Hawking not only gave us hope that time travel
is possible, he dreamed up a system of traveling
into the future.
Science fiction writers take note.
Hawking imagined a train track that goes around
the Earth.
This particular train would need to get as
close as possible to the speed of light in
order for it to become a time machine.
Passengers on this train would have a ticket
to the future.
The train would accelerate around the Earth
again and again, getting faster and faster
each time.
As the train gets close to the speed of light,
time will start flowing slowly on board, relative
to the rest of the world.
Hawking predicted everything on the train
would go in slow motion.
If said train left the station on January
1, 2050 and circled the Earth over and over
again for 100 years, before coming to a halt
on New Year’s day 2150, it would only feel
like a week had gone by for our passengers.
They’d leave the train having traveled 100
years into the future.
2.
Speed of Light
The biggest obstacle in our way of traveling
into the future is manufacturing a vehicle
that can travel extremely fast.
Not Ferrari fast, or spaceship fast; we’re
talking speed of light fast.
As mentioned earlier, if a spaceship were
constructed it would need to go significantly
faster than the Apollo 10, the fastest manned
ship on record.
Hawking supposed that based on the ship’s
size, it would take awhile to reach the speed
necessary for time travel.
After one week, according to Hawking, it would
reach the outer planets, then after two years
it’d reach half-light speed and be outside
our solar system.
Finally, after two years it would be traveling
90% of the speed of light.
That would place the ship’s passengers 30
trillion miles away from Earth, and the ship
would finally begin to travel in time.
“For every hour of time on the ship, two
would pass on Earth.”
1.
Stephen Hawking
There are few who did more to make the most
obscure and complicated science accessible
for those who wanted to learn more about our
universe.
Stephen Hawking did it all; writing books
and creating televisions shows that helped
educate the masses.
One of his greatest contributions to his field
comes in his expertise on black holes.
Hawking made a theoretical prediction that
black holes should emit radiation, which is
now known as Hawking radiation.
His contributions to singularity also cannot
be understated, working on several groundbreaking
theorems.
Hawking was a titan in his field, and there’s
been no greater voice in understanding the
cosmos, and man’s place 
in it.
