Can you artificially create gravity?

pu1. If there's a very high mass next to it, gravity increases, and you can't make that much mass in the lab

2017-11-13

OK

pu2. I heard that weightlessness is possible. I heard that astronauts practice in the space they made it

2017-11-13

OK

pu3. Don't astronauts usually practice underwater? It's similar to zero gravity

2017-11-13

OK