Time Travel

"Mr. Mubble?"

"Yes, Umber?"

"Does the Hubble telescope see back in time?"

"What?"

"Is it like a time machine? Cause you said it can see all the way back to the big bang."

"No, it's not a time machine."

"But, like, if you turned it on Earth, wouldn't you see stuff that already happened."

"No. Well, yes, but not very long ago."

"So, could you use it to look at historical events and see what actually happened?"

"No. The delay is whatever the speed of light is, so you'd only see back a few milliseconds. For instance, right now you're, what, ten feet away from me. Now, let's say you pass out riiiiigggghhht NOW."

"Huh?"

"Now, you're passed out, but I don't see it right away."

"Yes, you do."

"No, I don't."

"You're not going to just stand there while I'm on the floor."

"Well, not for very long. It takes something like three nanoseconds for the image of you falling to reach me, so there's a delay. If you pass out on the moon, the delay is longer. If you pass out on the sun, it's 7 minutes."

"Because if she's on the sun, all she's going to do is pass out," I muttered, forgetting momentarily that the sun is gaseous and you can't truly be 'on' it.

"Wait, so if I took Hubble to, like, Pluto, then would I see stuff that already happened?"

"Yes, but you won't see anything from before your telescope took off."

"Oh. Okay."