The size of the observable universe is often estimated to be about 93 billion light-years in diameter. However, it's important to note that the expansion of the universe affects this measurement, and the concept of "traveling from one end to the other" becomes more complicated at such large scales.
According to the theory of special relativity, as an object with mass approaches the speed of light, its relativistic mass increases, and it requires an infinite amount of energy to reach or exceed the speed of light. Therefore, it is not possible for objects with mass to travel at light speed.
However, let's assume for the sake of the thought experiment that you could travel at the speed of light. In that case, from your perspective, the distance would contract to zero due to length contraction, and you would experience the entire journey instantaneously. Time would effectively stop for you.
From the perspective of an outside observer, though, time would still pass normally. However, the observer would perceive your journey as taking zero time because the distance would be contracted to zero.
It's important to understand that this scenario is purely hypothetical, as current scientific understanding does not allow for objects with mass to achieve or exceed the speed of light.
In summary, if you could travel at the speed of light, you would perceive the journey across the observable universe as instantaneous. However, according to our current understanding of physics, it is not possible for objects with mass to travel at light speed.