What will happen, if all 7,000,000,000 people on earth simultaneously jump up and down?

If everyone jumps at home, nothing significant will happen. This is – noting at all. Even if we jump up and down the whole day long. But, if we were to collect all people of the earth in one place, we could very quickly solve a rather important problem: Overpopulation. Probably you have heard something about us humans multiplying our numbers far to quickly. There are just too many of us on earth. If nothing is done soon there won't be any food left. One way of looking at it, 7,000,000,000 is not so much, so all the people on earth could easily fit into a territory equal to the size of Moscow or Los Angeles, for example. And it wouldn`t even be crowded. Ok, let's say we all gather on a hypothetical huge platform one meter of the ground and are ready to make this collective jump.

What will happen?

This jump will create a truly significant amount of energy, part of which will return back to each person through their shoes. And, some of which will dissipate into the environment with very interesting consequences. First, you will hear a very loud sound of about 200 decibals, similar to the sound of applause, only much much louder. A jet engine emits a sound volume of 140 decibels. 160 is the level of a shock wave from a supersonic aircraft.
The pain threshold of a human being is already passed at a level of a mere 130 decibels and 135 to 140 decibels is a concussion.
150 shock and severe injuries and 200 decibels – at best such a sound will simply blow your eardrums.
That’s at best, but basically, everyone will just die.
Suppose you’re only deaf after the jump. Somehow, you survived. You are incredibly lucky, but not for very long.
It turns out that our jump strongly impacted the planet and in response to this degradation the earth will send a 30 meter high tsunami rolling back onto shore. Along with a couple of earthquakes of around 4 to 8 on the Richter scale.
As a consequence, bridges, railways, powerlines and some buildings will be destroyed.