Answer:
Physicists have built devices to move me very fast. My last seven letters can be commonly found in newspapers magazines and journals.
Though I am only two words I have thousands of letters in me
I walk on 4 legs in the morning, 2 legs at noon, and 3 legs at night. What am I?
I am lighter than air, but a hundred people cannot lift me. Careful, I am fragile. What am I?
I go up and down at the same time. Up towards to sky and down towards the ground
Some try to hide some try to cheat. But time will show we always will meet. Try as you might to guess my name. I promise you'll know when you I do claim.