what if one day we all woke up in the morning to find out that there are another 63 billion people (not aliens, civilized humans just like us), that just appeared out of nowhere. like they all came from one source and gradually wandered around the world in huge groups. what would happen to all the resources and food, and would the earth get too heavy and fall? i'm not sure, but this scenario has been givin me the spookers.
It depends, are we assuming that they all appear in proximity to existing people in proportional numbers? (i.e., 120 million show up in NYC, 3 million in Anchorage) or do they all just show up in one location?
If it's the latter, then they'll mostly all just die. A bunch of people suddenly concentrated in one area would cause huge logistical problems as the group spreads out. Those on the outer parts of the group would quickly exhaust all edible resources in the area, and basically everyone would die except for the few lucky people able to get away from everyone else.
So, the Earth's population would momentarily increase substantially, and then decrease massively to a population only slightly larger than the one you started with.
xkcd tackles a similar scenario in this question:
https://what-if.xkcd.com/8/