On which planet in the solar system will I age slower than on Earth?
How Old You'd Be If You Lived on Different solar system Planets?
This question can be answered in two different ways: the first of which is light-hearted
and joking, though numerically rigorous, while the second will also be rigorous from the
point of view of physics.
I thought that the only way to reconcile the two was to put it all in the form of an apologue
capable of making the point without boring.
To you the judgment!
In the far distant future, in which mankind had succeeded in terraforming and colonizing
the entire solar system, there suddenly arose on Earth a movement made up of people who
- in imitation of the group of "flat-earthers" that had spontaneously formed centuries earlier
- began to declare themselves tired of the complexity of science, giving themselves to
the craziest demonstrations of how to live decently without problems could be sufficient
to reason with their own heads.
This would not have been a bad idea at all, were it not for the fact that by "reasoning
with one's own head" the adherents of this anti-scientific movement meant, the rejection
and scorn of any sensible explanation of how the world works.
Difficult or easy it was to understand.
The world, of course, went on anyway.
but as is often the case in our day, even in that distant future the media presented
things in such a way that soon the exploits and rants of the "simple people" as they liked
to call themselves, filled the news and information networks throughout the solar system to overflowing,
making most people believe that a great social transformation was taking place.
Out of this came the birth of veritable gurus, capable of attracting larger and larger crowds
of Simples.
And larger and larger sums of money.
Just to name a couple, Creation came back into vogue and it was established that Pi
equaled 3, without all "those useless decimal places."
Then it occurred to someone to claim that on every planet in the solar system time had
to run differently than it did on Earth.
Were not the durations of the revolutions around the Sun very different?
And of course, according to them, if this was not yet in the public domain, it was the
fault of those who did not want the migratory flow to the other planets to be unbalanced
in favor of those that could ensure very slow aging.
This seemed like complete hogwash even to many of the Simples, but no one dared to say
so, since it was endorsed by one of the most influential gurus.
Unable to understand that it was a form of humor that hinted at the different ages we
would have on the various planets in the solar system, the Simples based their beliefs on
the fact that "even the astronomy books" sometimes reported this.
And to prove this they even organized a Kronos Project to determine how much was true or
false in what they asserted.
A conference was also called for the occasion, where they explained how they would proceed.
One of the gurus began by saying, We have considered eight planets: Mercury, Venus,
Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
In each of these, an affiliate of ours will be sent to live for ten years.
Or to put it better: a clone of one of our affiliates chosen from those in existence.
In fact, at the time it was now standard practice to produce in vitro large quantities of children
genetically identical to a given individual.
They were made operational (as we used to say instead of "delivered"), all on the same
day, to simplify and optimize formative care.
And of course, they were all indistinguishable from each other except for the identification
chip grafted under the skin.
All people born " from women," which were increasingly rare, gave rise to at least twenty
clones.
Which were then shunted to where they were most needed in the solar system.
At the end of ten years - the guru continued - the clones will be brought back, and compared
in appearance and function with the one left on Earth.
Thus we will show that each one will have experienced a different passage of time.
Applause ... a pause ... and then the floor was left to a retired astronomy professor,
who had candidly agreed to play devil's advocate in the meeting.
A figure strongly desired by the guru to show everyone that the Simples movement was not
afraid of confrontation.
Dear friends...
What is a day?
What is a year?
Our Earth, as we know it, is in constant motion.
In fact, it makes several movements, but specifically, there are two that might interest your strange
theories about the passage of time...
First, the earth rotates on its own axis.
Second, the Earth revolves around the Sun.
The period of Earth's rotation on its axis is how we define the day.
We further divide this period into 24 hours, each of which is divided into 60 minutes,
each of which is divided into 60 seconds.
There are no rules governing the rotation speeds of the planets; it all depends on how
much "rotation" there was in the original material that went into each one.
Jupiter, for example, is very fast, rotating around its axis every 10 hours, while Venus
takes as long as 243 Earth days...
The period of revolution of the Earth around the Sun, on the other hand, is how we define
the year: equal to just over 365 days.
We are taught as early as elementary school that planets move at different speeds around
the Sun, but while their periods of rotation are random and unpredictable, the times of
revolution are in close mathematical relationship to their distance from the Sun.
In practice, as was discovered by Johannes Kepler, the period taken by a planet to revolve
around the sun, raised to the square, is proportional to the average distance from the sun raised
to the cube.
Here is the formula: It is an enchanting formula in its immediacy-allowing
us to get the distance of a planet from the sun by knowing only its period of revolution,
or vice versa!
Let's take an example by relating everything to the Earth, which is 149.6 million kilometers
away from the Sun, or 1 AU: Jupiter's distance from the Sun is 5.2 AU, and then its period
of revolution, or its "year," will be 5.2^3/2, or about 11.8 years!
Extraordinary, isn't it?
But where does this cosmic architecture come from?
It was Isaac Newton who guessed that the movement of bodies on Earth, the movement of the Moon
around the Earth, and the planets around the Sun have a common cause: a universal attractive
force acting on all bodies.
Specifically, the force that is released between two bodies is directly proportional to the
product of their masses and inversely proportional to the square of their distance.
This means that the more massive and closer the bodies are, the more intense the force
that attracts them.
This force was called gravity.
From this simple idea, Newton developed a very powerful theory, called the Theory of
Universal Gravitation, thanks to which the motion of any body subject to the force of
gravity can be studied and predicted with extreme accuracy.
The Theory of Universal Gravitation represents one of the highest heights ever reached by
human ingenuity; it provides results with precision beyond all expectations.
Even today, Newton's theory is of fundamental importance for the study of the motions of
celestial bodies.
Well, all this is to justify the numbers we are about to see on the screen, which will
give us planet by planet the parameters that you Simples have put at the basis of your
theory.
"Hey, guys, just a moment before we continue...
BE sure to join the Insane Curiosity Channel...
Click on the bell, you will help us to make products of ever-higher quality!"
Let's start with Mercury.
Distance from the Sun of 0.387 AU; Revolution period of 88 days, equal to 0.24 Earth years.
On Mercury will go MER, just turned 30--which is of course also the age of all the other
clones.
The real names will remain kept secret.
For the past few centuries, Mercury has been an intensely colonized planet in the polar
regions.
If the hypothesis of you Simpletons turns out to be true, by the time of its return
poor MER should have aged 10/0.24 years, or .almost 42 years!
And thus have an age of about 72 years!
I don't think he would be very happy about that…
A few better (or less bad) things would go for VEN, which you are about to send to one
of Venus' atmospheric colonies.
So let's see...
Venus: distance from the Sun of 0.723 AU; Revolution period of 225 days, equal to 0.615
Earth years.
By your reasoning on its return, VEN should have aged 10/0.615 years or about 16 years!
And thus have an age of almost 46 years!
Obviously, for the clone EAR, which remained on Earth, after 10 years it will have been
10 years and he will be 40 years old.
MAR will be sent to the colony of New Rome, on Mars, and fortunately for him, he should
be among those clones that you Simples think will be destined to age slowly.
Mars is 1.524 AU from the Sun and orbits around the Sun in 1.88 years.
By the time MAR returns, it should have aged 10/1.88 years, or .about a little over 5 years!
And thus have an age of 35 years!
Even better will be the case for JUP, which will spend its next 10 Earth years on the
surface of the Dyson sphere being built around the gas giant.
JUP is 5.2 AU from the Sun and thus orbits around the Sun in 11.86 years.
On its return, JUP should be aged 10/11.86 years, or .just 0.84 years old!
And thus have an age of not even 31 years!
But this, I want to remind you, only if this silly hypothesis of you Simples is confirmed...
But let us go on...
SAT is about to depart bound for Hexagon City, the huge orbital platform located just above
Saturn's north pole, at the upper limit of its clouds.
Saturn is 9.54 AU from the Sun and orbits around the Sun in 29.5 years.
By the time SAT returns, it should have aged 10/29.5 years, or .0.34 years, just over 3
months!
And thus have retained an age of 30 years!
URA is about to depart bound for Herschel, the second largest orbital platform, also
located above Uranus' north pole...
Uranus is 19.2 AU from the Sun and orbits around the Sun in 84 years.
On its return, URA should be aged 10/84 years, or .0.112 years, a little less than a month
and a half!
So, too, it should return at an age of 30 years!
NEP is about to depart bound for La Ville de Leverriere, an orbital platform still under
construction above Neptune's north pole.
Neptune is 30 AU from the Sun and orbits around the Sun in 164 years.
By the time NEP returns, therefore, it should have aged 10/184 years, or .0.05 years, just
under 20 days!
And it should therefore present itself as 30 years old as when it left!
That is all, dear gentlemen...
Needless to say, in my humble opinion, none of this will happen...
Your clones will return to Earth aged 10 years, exactly as they were left here.
In fact, no.
I was wrong to say "exactly."
Of course, being twins they will all appear to have aged the same... but an albeit very
small difference will be there...
A difference that ironically is completely predicted by that "complex" science that you
so detest.
What am I talking about?
Well, about the true dilation of time, the only one possible: is that described by general
relativity.
Basically, Einsteinian relativity says (and has been shown) that the speed at which time
flows depends on the intensity of the gravitational field in which one is immersed and the speed
of the observer.
A clock in space away from any gravitational influence will tick faster than one located,
for example, on a planet.
Heavy things such as planets actually create a gravitational field that slows down time
nearby.
How much faster depends on the mass of the planet.
So basically you are right: living on different planets leads to different aging rates.
But certainly, not in the amounts, you imagine.
Compared to EAR, which remained on Earth, URA will return from Uranus older by 3.9 seconds.
Compared with EAR, which remained on Earth, NET will return from Neptune older by 3.8
seconds.
Compared with EAR, which remained on Earth, SAT will return from Saturn older by 2.1 seconds.
Compared with EAR, which remained on Earth, MAR will return from Mars older by 1.8 seconds.
Compared with EAR, which remained on Earth, VEN will return from Venus younger by 1.7
seconds.
Compared with EAR, which remained on Earth, JUP will return from Jupiter younger by 2.4
seconds.
Compared with EAR, which remained on Earth, MER will return from Mercury younger by 7.1
seconds
You were surprised, weren't you?
Mercury is the planet where it ages the slowest.
And this is because of its high orbital velocity and the fact that, despite its small mass,
it enjoys, more than the other planets, the proximity to the Sun's very deep gravitational
well.
What if we wanted to consider the Sun as well?
Well... a hypothetical clone called SUN, capable of remaining there 10 years, would then return
to Earth younger by 663 seconds, or more than 11 minutes!
There, that is the answer you will have 10 years from now when you examine the chronograph
display under the skin of your clones returned to Earth.
Science, dear friends, is a simple thing...much more so than your somewhat whimsical ideas...which
are not simple, just simplistic!
I'll see you back here in ten years.
Maybe.