What happens if gravity is reversed

I know it's far fetched but thought I'd try anyway. Suppose the Earth was falling into a black hole. To a first approximation the Earth and the people on it will be accelerating at the same rate, so people would not be sucked off the surface.

After all, the Earth and the people on it are accelerating towards the Sun but we are not pulled off the surface every midday. But the acceleration of the Earth and the people on it is only the same when tidal forces can be neglected.

At midday on the equator your centre of mass is nearer the Sun than the Earth's centre of mass, so the Sun is pulling on you slightly more strongly than it pulls on the Earth. However the difference is tiny compared to Earth's gravity. But suppose a small black hole, say one the mass of the Earth, were to pass just over your head. In this case the tidal forces would be strong enough to pull you off the surface of the Earth and to a messy death!

I would say a black hole passing or being sunked in is not reversing gravity. Reversing would be more like totally reversing gravity and all its effects all matter would repel itself. Sign up to join this community.

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? That's where the apocalyptic devastation somewhere along the lines of a Michael Bay movie come in. A sudden and significant loss of air pressure would immediately shatter everyone's inner ear.

Think about the pressure that builds when you're flying or scuba diving; this would be much more intense and immediate. Concrete structures would crumble as oxygen — an important binding agent — left the planet [source: Cote ].

What's H 2 O without the O? That's right, water would become hydrogen gas, causing immediate explosions among every living cell. Sure, it would be over in five seconds, but none of us would be around by the time the gravity came back [source: Cote ].

Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Science Vs. What If. For example: planet Earth. Every particle in the Earth is pulling on you at this very moment—every single one.

You can jump really high despite that. McCluskey said this is because gravity is a wimpy force, an oddball compared to other forces of nature. If gravity pulled us up toward the sky, it would mean that gravity repelled. It would push objects away from each other. Watching this happen from out in space, you could see everything not bolted down to Earth—buildings, desks, homework, cats—start to lift off and drift into space.

Then, you could see the surface of the earth start to fall away. He thinks your question sounds like a good idea for a science fiction story. As you may already know, or as any astronaut can tell you, you can live without gravity.