14 DAY TRIAL // While traveling at or near the speed of light is known to produce interesting relativistic effects, actually being a photon is even weirder. Scientists say that these elementary particles – were they to be conscious – do not experience a lifespan in the strictest sense.
In other words, from their own perspective, they are emitted and then instantly absorbed, nearly at the same time, regardless of the fact that they appear to have traveled for billions of years before we notice them here on Earth.
In objective terms, photons can travel anywhere from fractions of a millimeter – such as for instance inside stars – or billions of years. In the latter case, light particles that were emitted in the early Universe are only now reaching our location, but time is irrelevant to them.
In other words, both time and distance are irrelevant to light particles. The purpose of the new theoretical study was to demonstrate that time and distance are in fact intertwined, as in two different aspects of the same thing.
When larger objects attempt to approach the speed of light, a host of relativistic effects set in. One of them is the slowing down of clocks, which occurs in direct proportion to the speed at which the aforementioned objects are traveling.
To an observer moving with these objects, both time and distance appear to contract. A similar effect is seen when an object approaches a massive celestial body, such as a star, planet or moon. The intense gravitational pull of the object affects both space and time in its surroundings.
It is important to understand that spacetime is distorted in a variety of ways, especially around bodies capable of generating an impressive gravitational force. In the new study, researchers give the example of a spacecraft traveling through space at constant velocity.
From the astronauts' perspective, they will continue to experience weightlessness until the point that they collide with the surface of the planet. However, for an observer on the surface, they will appear to be accelerating until they collide.
The reason for this discrepancy is that spacetime is more crunched up the closer you get to the surface of an object in space. As such, a spacecraft may appear to move faster, but this is only an effect that generates the illusion of a causing force, Universe Today reports.
However, the acceleration is not caused by an external force, but by the very nature of spacetime in the planet's surroundings. Similarly, gravity is not a force in itself, but simply a convenient, easy-to-understand interpretation that we developed for the curvature of spacetime around Earth.