There are many mysteries of science out there in the world, join us now as we explore the
one known as the Einstein Twin Paradox.
7.
What Is The Twin Paradox?
This is going to get a bit complicated, so allow me to paint you a picture that will
help you understand it a bit better.
I want you to picture a pair of twins, ones that are the exact same in every way.
One day one of them gets selected for a mission that will send them into space, and they'll
travel 86.6% the speed of light to a star that is 10 light years away.
The other will just be an observer on Earth, "watching" the stars to try and see where
their twin is, but otherwise not doing anything special.
You follow so far?
Good.
So, here's where the problem comes to light.
Because you have a person moving close to the speed of light.
And science dictates that the faster you move through space, the slower that time moves
for you.
This won't happen with the technology that we have right now because we're not moving
anywhere close to the speed of light (which for the record is 670,616,629 mph).
So moving say 60 miles per hour isn't going to affect time around you because light is
moving much, MUCH faster than you are.
Understand?
Going back to the astronaut, as they fly through space, they're going to meet a scientific
principle for their travels known as the Lorenz Factor.
The Lorenz Factor helps show how much time will be sped up or slowed down via your movement
in space.
It's a complex math equation so I won't bore you with that.
But needless to say, if said twin in said spacecraft going 86.6% the speed of light
was to go on a ten lightyear journey, they would feel time going twice as slowly.
Despite the universe itself going at the same rate as usual.
To the extent that the technological instruments that would be on the astronauts craft would
also register time going slower because they're going so fast.
Here is where the paradox comes in.
The total trip for the astronaut to the star and back should take 23 years.
But, they're going to feel time going slower by a factor of two.
Therefore, who is the older twin when the astronaut reunites with them back on Earth?
6.
Both Sides Of The Equation Mind blown?
I'm sure it is.
But I'm also sure that some of you aren't sure why this is a paradox at all.
Here's why some of you might think that way.
You think that because the astronaut twin is traveling through space, regardless of
the time they're "feeling", they're still going faster than the twin on Earth.
So by that token, the Earth twin is older because they're feeling the effects of time
in the regular way, and thus when they return 23 years later, the earth twin is older.
But, because of the concepts of near lightspeed travel, it can also be stated that the astronaut
twin isn't actually moving in the normal sense.
They're perceiving time in an abnormal way, meaning that they perceive time going slower
as the universe moves around them.
And by that token, since they're perceiving time at a slower rate, and their bodies aren't
registering time in the normal way, but in a slower way, they are going to be older than
their twin back on Earth.
Neither theory is wrong, as they're both backed by various scientific principles, but both
can't be right because that would create a paradox.
So which is it?
Which one is older, or, are they both the same age despite the traveling and lightspeed
travel that has gone on here?
What is the true answer to this paradox?
5.
It's Not Really A Paradox Did I blow your mind again?
I'm sorry, but I promise this will make sense by the time that this is all over.
The problem here is that while the Einstein Twin Paradox is special, there honestly is
a definitive answer as to which twin will be older and younger by the time this is all
over.
And that in turn reveals the big misconception about the paradox as a whole.
Because while time may be constant in its own right, the problem lies with the astronaut
twin.
Mainly in that this twin isn't moving in the same direction throughout her trip.
Remember, this example with the twins depends on how the mission itself goes.
The astronaut twin is going to the star ten light years away and is then returning back
to Earth.
And as you know from how the universe works, the Earth, and by extension the star, are
not in the same place every single day, or even year.
So, the astronaut twin is actually going in two different directions at a speed that is
only constant in one direction, while the earth twin is in the same place at the same
speed going in a constant state of motion.
And thus, when you end up back on Earth, because the astronaut twin is experiencing time half
the speed as the Earth twin, the astronaut twin is actually younger by a factor of 2.
So while the Earth twin is waiting 23 years for the twin to return, the twin in space
is experiencing the trip itself only taking about 11.5 years.
Thus the age difference.
This is known as special relativity, because they're each experiencing time in their own
frames of mind and body, yet experiencing time differently.
Don't worry, we'll explain more about what's going on, but before we do, be sure to like
the video and subscribe to the channel so that you can watch all our weekly videos!
4.
The Light Experiment You're still confused about all of this, aren't
you?
Don't worry, I fully understand that.
So allow me to explain this to you in more basic terms.
Using a graph to show the "journeys" of the two twins, sound good?
Ok, so we have two twins, one on Earth, and one about to be launched into space.
So they both start off at the same point.
For the Earth twin, her place on this graph is very simple, and constant.
She's staying on Earth for all 23 years.
So every tick up this graph is 1 year, all the way up until 23.
However, for the astronaut twin, not only are they going 86.6% the speed of light, which
delays time by a factor of 2, they're also going 10 lightyears from Earth and then eventually
coming back to Earth.
Now, to help the twins understand what is going on for the other, the twins agree to
send a beam of light from where they are to where there twin is on Earth or in space.
Just believe for a minute that they have a laser or beam of light powerful enough to
do this.
They agree to send each beam of light for when a year passes in their own time.
The Earth twin starts this whole thing off, and send a beam of light to the space twin.
But here's where the relativity aspect comes into play, because a beam of light will take
the same amount of time to travel no matter where it is in the universe and no matter
where its sent from.
And thus, the relativity comes in to play.
Because as you'll see on this graph, when the Earth twin sends a beam of light to the
astronaut twin, the astronaut twin will perceive time going slowly for them.
Making it seem like their twin is aging more slowly.
Only when they get on the return trip to Earth will the beams of light start to go even "faster"
in terms of frequency, and thus make it appear as though the twin is now aging faster.
But how exactly does that work with the astronaut twin?
Why is the twin in space seeing things slower and then faster?
Remember, it's not just about time, it's about distance.
3.
The Journey The problem with the Twin Paradox is that
people forget that the space twin is on a journey.
A piece of light will take one year to travel a full lightyear (hence the name), but for
the astronaut twin, they're not just going close to the speed of light, they're starting
off their journey by going AWAY from where the beam of light originated.
So not only does the light beam have to travel to them, but it has to play catchup for much
of the journey.
To the extent that by the time the Earth twin's second beam of light reaches the astronaut
twin, the space twin will already be on their way home to Earth!
Then, because of the new direction and speed they're still going at, the beams of light
will start to reach them more quickly because of the fact that they are traveling TO the
place where the beam of light is emanating from and not AWAY from it as they originally
started their journey.
So in the eyes of the space twin, the first two burst will come very long distances apart.
And then, they'll appear to be coming rapid fire at them as a "year" passes in the eyes
of their twin.
In reverse, the Earth twin will think that their space twin is aging slowly at first,
to the extent that the first six bursts of light sent out by the space twin will take
a total of 21 combined years to be seen by her.
Then, the remaining ones will be seen rapid fire.
Thus making the Earth twin think that the space twin is aging more slowly while then
aging rapidly within the last two years on Earth.
Like I said, this is a pretty complex thing, and the problem here is the belief that they're
both experiencing time in the same way, when we've already established that they're not.
But, the real problem is the belief that both of them are "inertial observers".
2.
Inertial Observers What is an inertial observer?
That is a being of whatever kind maintaining a constant speed and direction in the universe,
and then observing said universe through that lens.
So we here on Earth right now are all inertial observers, because our planet orbits the sun
at the same rate and in the same orbital direction for 365 days in a year (with the exception
of a leap year to be clear, but even then).
So for us, time moves as it should, in a singular direction, in the "right way" and at the right
speed.
Despite people saying that "time flies", it honestly doesn't, and thus, we're all inertial
observers so long as we maintain our speed and place on the Earth.
The space twin however is NOT a inertial observer, because they are moving through the universe
at a constant speed, but NOT a constant direction.
Rather, they're going one direction for one half of the journey, and then they're coming
back to where they all started in a completely different direction.
That's why the graph looks like it does.
Because they're doing a journey that isn't orbital, or even linear, it's perpendicular.
Which causes special relativity in regards to time, and the Lorenz factor helps make
them feel like the universe is moving all around them when in fact they're just maintaining
a special view on time as a whole.
In the end, the space twin is honestly going to be younger by their twin by about 11.5
years because they moved through space and time at a rate and direction much different
than their other twin.
Thus, this really isn't a paradox, as the two solutions may seem to match up at first,
and thus cancel each other out because both can't be true, but in the end, the truth is
there for you to see as long as you're willing to listen and work it out.
1.
Why Did People Think This Was A Paradox For So Long?
While it's true that the Twin Paradox has been solved, it wasn't always that way.
In fact, this paradox goes all the way back to 1911, so people have been talking about
this for over 100 years!
But why is it that we now have an answer, but we didn't back then?
It's very simple, it all has to do with time in the literal sense.
Much like humanity once believed that the Earth was the center of the universe, and
that the sun revolved around us, we erroneously believed that time worked in one way, but
in fact, it worked in another when it came to lightspeed travel.
That's not an indictment on our race, but rather, proof that we still have more to learn.
Which is something that the human race often strives to do.
They try and keep going, they try and keep learning, and they try to keep understanding
what they think they know about the universe.
This is also a case where we can't exact go and test this ourselves.
Because we don't have a vessel that can travel 86.6% the speed of light.
And if we could, we certainly would've reached Mars by now.
Sadly, we don't, and thus all we had were theories and beliefs about what could be possible
and what is possible.
Thankfully, we do have the answer, and it is one backed by science of many kinds, so
now that we know that, we can move on.
And if someone brings up the paradox and says the wrong answer to it, we can correct them.
Thanks for watching everyone!
What did you think about this breakdown of the Twin Paradox?
Do you think you better understand the principles that are outlined in this paradox?
Or do you still not understand what's going on here?
Let me know in the comments below, be sure to subscribe, and I'll see you next time on
the channel!