Let's go a little far in this article... Well, we will go quite far. Space… have you ever thought about how time is formed in space? We all know that time flows in space differently than earth. Have we ever thought why or how?
Let's try to understand what space is first. We can use fish - sea analogy for this. In here, the fish represents us and the sea represents space. Space covers everything, including us.
Aristotle had the first idea on this subject and said that space contains nothing. Before Aristotle, Democritus said that space contains something, but he did it in such an indirect way that he was not understood to mean space. In fact, Democritus spoke of atoms and hitting each other. He claimed that these atoms also formed nature.
Today it is defined as the space in which there are things and atoms in space. Fields such as gravitational field and electromagnetic field dominate this space. Now let's move on to the topic of space and time, we will use the tarpaulin analogy to warp space-time.
Let's say we stretch 3 people on a tarpaulin. Then we put an iron ball on the tarpaulin. When we put the ball, the shape of the tarpaulin changes right? Let's put a plastic ball next to this iron ball. The plastic ball is displaced due to the curvature of the iron ball. Space-time is like that, they can undergo deformation with masses.
If we sum up what is meant here, space and time are not two separate concepts, as Newton said. They are interconnected and inseparable concepts, as Einstein tried to show.
Gravity is not actually the attraction of two masses to each other (this is Newton’s theory). Caused by the spacetime warping of the iron ball in spacetime [3]
But is the light affected by this gravity?
This issue is actually very complicated. Because photons don't have mass. And logically, we cannot expect something without mass to be affected by gravity. Photons are massless at rest. When they move, they have kinetic energy due to their high speed. According to Einstein's special relativity in outline, energy and matter are the same things. So when light is in motion, it has a small mass. And it is affected by gravity while in motion. We can say that the higher our speed, the less we are affected by gravity. We know that the fastest substance is light. So there is nothing faster than light. Then we can say that if light is affected by gravity, even a little, every object is affected by gravity.
We talked about topics such as space-time, gravity, but does this have anything to do with time as we know it?
According to Einstein, gravity can speed up and slow down the flow of time. The greater the gravity, the slower the time.[1]
There is also a relationship between time and motion;
If an object is moving, time flows slower for that object than when it stops. But the observer becomes aware of this, not the object. If two objects are at rest, time flows the same for them. But when one starts moving, the flow of time changes relative to each other.
This situation is the same for us humans as well, but we do not notice it because our speed is very low.[2]
As a result, if we summarize what we told:
Gravity is not like a rope between two objects. It is mostly due to the warping of space-time with a massive object.
According to relativity, time and space are inseparable concepts.
Gravity and motion affect the time
The greater the gravity, the slower the time.
Time is slower for moving object than motionless
Sources:
[1]Emecan, Z. (2019, December 18). What Is Curved Space Time Simply? August 2020 tarihinde Cosmic vortex: https://www.kozmikanafor.com/egri-uzay-zaman/ adresinden alındı
[2]Space - Time Concept |. (2014, july 17). August 2020 tarihinde https://www.elektrikport.com/teknik-kutuphane/uzay-zaman-kavrami-zaman-herkes-icin-farkli-mi-isliyor/12179#ad-image-0 adresinden alındı
[3]Space or Time: What Should We Understand From Space-Time? (2012, october 14). august 2020 tarihinde evrimagaci: https://evrimagaci.org/uzay-mi-zaman-mi-uzayzaman-kavramindan-ne-anlamaliyiz-853 adresinden alındı
