Lets define time — lets suppose you are immortal (no biological changes in body) & confined in a airtight room with no watch — a closed system, nothing enters in, nothing goes out — No Exchange whatsoever !
What do you observe ? No change whatsoever — no event, all boring & monotonous.
So you can say time stops for you !
Why because you don’t see anything happening, now you can argue that your heart is beating & count is increasing with every breath, so lets for argument sake assume you have no heartbeat, no change in your biological body..no change in your thought process..you are still & numb, you are Kind of trapped, a state of limbo..now you can safely say time has stopped !
That is how you define time. Time is measure of changing things in space around us. It needs some oscillating events happening in cosmos to calibrate itself, scientist feels that most accurate way to measure time is by taking vibrations of an atomic or molecular system as least count of time(atomic clocks). They found it to be closest instrument in cosmos which would carry same intervals between oscillations to define one smallest unit of time.
But Still no one accurately knows when the time itself started, was there someone in cosmos to measure when all chaos started of cosmic creation , because it is mostly a dimension based on observation …when you observe something , you calibrate it by time.
So there are many relative points to measure time, as like when a marathon race starts, referee fires a gun to measure a start time or when a rocket fires from launch pad — count down is started or our cosmos time — time started from zero when big bang occurred & may end with big crunch (when there is no body to observe.)
Then what is speed of time ?
Time is dimension which is calibrated from your frame of reference as above examples & established by special theory of relativity.
If a star at a distance of one light year from earth exploded in space, light from event would reach us after one full year , so we at earth say → See that star as exploded today , but that is false statement , star had exploded one year back but we watched that event today …that is how time works in cosmos, our ability to observe using speed limit of light defines time, time is not a universal dimension, it changes with each frame of reference.
So when you travel at speed of light in a space ship away from an idle observer then time has zero speed, it stops ,time stops for you , i.e..if an distant observer is observing you.. you are just still in space with no movement …reason they cannot observe any event going around you as you are already traveling at speed of light away from them & to observe & assimilate a information , light from observer must approach you ..but here since you are faster than anything possible, nothing would come near you…& therefore for you time will become invariant or Simple Time Stops from perspective of an distant observer.
If you are still in space with zero speed w.r.t to still observer in same frame of reference, time travels you at the speed of light .
That is speed of time — it depends on your frame of reference w.r.t Observer watching You.
