Visvarupa Darsana Yoga-Bhagavad Gita Chapter 11 [The Vision of the Universal Form]
Krishna Said > Shaloka: 7
Whatever you wish to see can be seen all at once in this body. This universal form can show you all that you now desire, as well as whatever you may desire in the future. Everything is here completely.
No one can see the entire universe sitting in one place. Even the most advanced scientist cannot see what is going on in other parts of the universe. Krishna gives him the power to see anything he wants to see, past, present and future. Thus by the mercy of Krishna, Arjuna is able to see everything.