Your Head is slightly older than your Feet: One evening in the spring of 1905, Albert Einstein, a patent clerk in Bern, decided to ride in a tram car on his way home through his day job.
It was one of the experiments of ideas he had prepared on a tram car that revolutionized modern physics forever. While walking away from the Zeitglog Clock Tower, Einstein imagined, what would happen if the tram car was retreating at the speed of light.
He realized that if he traveled at a speed of 186,000 miles per second, the clock needles would freeze completely. At the same time, Einstein knew that the hands on the clock tower would stick at their normal pace.
Time had slowed down for Einstein. This thought blew his mind. Einstein concluded that the faster you go into space, the slower you move over time. How can this be?
Einstein’s work was strongly influenced by two of the most distinguished physicists ever. The first was the laws of motion discovered by his idol Isaac Newton and the second was the laws of electromagnetism laid down by James Clerk Maxwell.
Newton Laws of Motion – Relative Velocity
Newton’s laws asserted that velocities are never absolute but always relative, so their magnitudes must be added by the phrase “with respect to”.
For example, a train runs at a speed of 40 km / h, which is in relation to a resting person. However, it travels only 20 km / h in relation to a train traveling 20 km / h in the same direction. Or it travels 60 km / h in relation to another train running at the speed of 20 km / h in the opposite direction.
This is also true for the velocities of the Earth, the Sun, and the entire Milky Way galaxy.
Newton, Maxwell, and Einstein
On the other hand, Maxwell found that the speed of an electromagnetic wave-like light is set at 299,792,458 m / s, no matter what it sees.
However, Maxwell’s assumption seems inconsistent with Newton’s assumption of relative velocity. If Newton’s laws are indeed universal. Why should the speed of life be an exception?
This presented Einstein with a difficult dilemma. This conflict between Newton and Maxwell’s ideas can be demonstrated with another brilliant thought experiment by Einstein.
Einstein imagined himself on a train platform and saw two bolts of electricity hitting each side of him. Now because Einstein stands exactly in the middle of the two strikes, he receives the resulting light beam from both sides at the same time.
However, things get more complicated when one sees the incident overtaking Einstein at the speed of light in a passing train.
If the speed of light conforms to the laws of relativity, then the person onboard the train will not witness the lightning fall simultaneously. Logically the light closest to the man on the train would first reach it.
The measurement of the speed of light made by both men will vary in magnitude, this would contradict a clearly fundamental truth of the universe.
Einstein had to make a difficult choice. Either Newton’s laws were incomplete or the speed of light was not a universal constant.
Einstein felt that with a small change in Newton’s laws the two assumptions could co-exist. To get rid of the discrepancy in the measurement, Einstein suggested that the time for the man on the train should be slowed to compensate for the decrease in speed so that the magnitude would be constant.
Einstein called this absurdity “time dilation” and his new theory “Special Relativity”.
Newton believed that time moves non-stop in one direction. However, Einstein however had just realized the time stretches and contracts to vary with velocity due to its malleability time like space deserved its own dimension.
Gravitational Time Dilation – Albert Einstein
In fact, Einstein claimed that the two were one and together they created a four-dimensional fabric or continuum called space-time.
On which the earthly events of the universe will emerge. Einstein suggested that giant objects such as the Sun do not pull objects like the Earth from a mysterious inexplicable force, but instead rotate the space-time fabric around them.
Forcing the earth to fall into this steep valley. A highly simplified analogy is a dip in a trampoline created by a falling ball. If a marble is placed on that trampoline then the marble is immediately rolled towards the bowling ball in the center, the same is true for the Earth’s gravity.
We are standing on the ground because the space that is so distorted by the mass of the Earth pushes us from the top down. However, the degradation of the fabric around the Earth is not uniform and the gravity of the Earth becomes less intense as we move towards its center where the curvature is maximum.
Therefore, like a marble on a trampoline, an object falling towards the earth accelerates as it runs towards the center of the planet. It falls rapidly when it is just above the surface when it is slightly above the atmosphere.
But hey, according to special relativity, the faster you move in space, the slower you move with time. This means that time moves slower on Earth’s surface than above the atmosphere.
Now, because different planets have different masses and thus have different gravitational power. They also move objects at different rates as we have learned that this means a variable path of time.
The same happens in the film Interstellar when the protagonist lands on a planet in proximity to a black hole. Gravity on the planet is so severe that one hour on the surface is equivalent to seven years on Earth.
How Speed affects Time?
To understand how speed affects time, let us consider the simplest timekeeping mechanism. One second pass each time the photon is reflected.
Let’s imagine two people, one in a spacecraft slightly above the Earth’s atmosphere and the other on a small hilltop just above the Earth’s surface.
The two see a man falling from space to the ground. Let’s say that the falling man is carrying the photon clock explained a moment ago.
As the man falls from them, what does each of the two see? What they see is exactly what a stationary person sees as a ball bouncing in a moving train.
As the man falls from space, the light in his watch appears to be rotating in triangles for two observers. This would mean that light travels a longer distance as a result of increasing the duration of one second.
It is clear that the length of triangles detects light and therefore the duration of one second is proportional to the velocity of the falling person.
When we remember that objects near the center of the planet fall fast, we can determine that time will be slower for humans on the hill.
Then it does the man of the spacecraft above. Of course, the difference is limitless. The difference between the time measured by the clocks at the top of the mountains and at the Earth’s surface is a matter of nanoseconds.
Your Head is slightly older than your Feet
Time dilation affects every clock, whether it relies on basic electromagnetism or a complex combination of electromagnetism and Newton’s laws of motion. In fact, biological processes also slow down. Yes, it is true that Your Head is slightly older than your Feet because the effect of gravity on your feet is more as compared to your head.
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