Question: How we can reach the speed of light? If we can reach that speed what are the consequences?

Hi tibi,
this is indeed quite a complex question! To answer this I have to recall all my knowledge in special relativity, I hope it goes well…:-)
Light speed is a bit less of 300000 km/s, and at the moment, with our technology and understanding of the physical laws of the universe, there is no way we can reach the speed of light.
This impossibility comes indeed from the “consequences” of travelling at light speed, or even from the consequences of the attempt to travel at light speed.

In fact, as an object speeds up, its mass increases compared with its mass at rest. This increase in the so called “relativistic mass” makes it impossible to reach light speed, because, as we approach 99.9% of light-speed, the mass of our object would reach something close to an infinite mass. At that point whatever engine/power supply you are using, it would need an infinite energy in order to move the infinitely massive object, and thus it would be simply impossible!

For this reason, no normal object can travel as fast (or faster!) than the speed of light. At least with the knowledge we have now about how an object can move, and how energy can be provided to that object.

Interestingly, since at that speed space and time are closely related, if you would travel on an object as fast as (almost) light speed, the concept of time would also change.
In fact, for an observer on Earth, this object (with you inside!) would seem to slow-down, and eventually stop at light-speed.
To you, nothing would seem out of the ordinary, except for the fact that all the activties on Earth would be happening super fast.
It would be like for you time is passing “slower”, and when you’ll be coming back on Earth, you would notice that everybody grew older, and you stayed the same.
That’s weird, and also, we never tried, so we are not sure if it would really work like this.
But who knows, maybe in the future we’ll understand something new about our Universe, opening for light speed space and time travels.
I hope to be there, then 😉