*SPOILER ALERT* if you haven't watched Upside Down [link, link] please don't read.

I've watched the movie and has been bothered by their concept of double gravity and many other things, but keep in mind that this is solely JUST FOR FUN. I don't hate the movie or anything.

Ok, so the movie starts off by explaining their mysterious unique place in the universe. Their solar system is known for having what is called double gravity. It has two planets whirling around each other around the sun. Each planet have its own gravity.

There are three basic laws of double gravity.
  1. All matter, every single object is pulled by the gravity of the world that it comes from, and not the other.
  2. An object's weight can be offset using matter from the opposite world - inverse matter.
  3. After a few hours of contact, matter in contact with inverse matter burns.

First of all, never say Solar System when you're referring to other systems (star system or planetary system). Solar System is our Sun and planetary system together. Next, two planets whirling around each other means that their gravity influences each other. By the first law of double gravity, the two planets' gravity shouldn't influence each other's gravity at all. So yeah, first law is already broken. Unless both planets have a lot of inverse matter, well that could also turn both planets into whirling fireballs.

Law #1 is very vague, all matter in the universe are there what if an asteroid hit a planet, then it's harvested to create a new object. Does that object belong to that planet now? Who assigns it? And all planets are formed by space rocks. So yeah, let's just ignore the flaw.

Next, there's a corporate building owned by Transworld that connects both planets which looks like this:

Transworld as depicted by the great artist, Jeric Dy

With Transworld built like this, it means that the way both planet have one center of axis for rotation while orbiting around its star. This also means that the area close to the Transworld building have no sunlight during afternoon since the other planet is blocking it. Unfortunately, the latter part of the movie, shows Adam and Eden had a lunch date, you know, with sunlight...

sunlight

Next, if you've played with magnets, you'll know that the magnet pull magnetic objects stronger when they're closer and weaker when further. The same principle works for gravity. So jumping while shoulder riding a person from the other side would have been almost the same as doing it on our world, since the person from other side is far from his/her planet.

space jump!

But if it does work that way, here's what I thought the scene should have been like:

from Adam's perspective
from Eden's perspective

Anyway, this also mean that removing inverse matter while you're on the opposite planet won't bring you back to your planet. Again, if it does work like that, prepare to leave the opposite planet's atmosphere and enter your planet's atmosphere in just 15 seconds.

During the love making scene near the end, we see that Adam and Eden whirling around while airborne:

I looks magical and beautiful but double gravity (in this world) doesn't work that way. Touching or hugging another person from the other side doesn't pass your gravitational pull to the other. It should have been like this:

... and very tiring, really really tiring.

At the end of the movie, we're presented with their world's new future. Buildings, besides Transworld's, are linked from both planets:

OK, hold on, the world is not flat. Let's zoom out a little...

There's a little problem here. In order for these buildings to be linked this way, the buildings have to be built slanted. The further from the center axis, the more slanted it should be. Which means some part of the world have buildings like this:

It must be a weird place to work on. Well anyway, I hope you enjoyed this post. Bye!