With no portal the shit hits the shovel and you flick it, transfering the speed of the shovel into the turds. You stop the shovel and the turds fly away.

Now imagine the shovel has a big rusty hole in it. So it's like a n shape. No portal yet. You go to flick the dog dumps but you just pass straight over them with the hole and the dumps go nowhere. The dumps have gained no momentum because nothing touched them and transferred that to them.

Now put a portal on the end of the shovel. As you sweep it over the cack has anything touched them? Has any object transferred it's momentum to the dog eggs? No, so the dumps just gently tumble out of the other side of the portal.

[–] Maticzpl@programming.dev 11 points 1 year ago (1 children)

Imagine there being 2 portals on the shovel one on the front and one on the back Whatever passes through remains in the same place. THIS is the actual analoge for the rusty hole. Entering the first portal the shit gains the speed of the shovel but since the exit portal is also traveling with the same speed but facing the opposite direction, it effectively cancels out the previous speed gain. Imagine it like the first portal adding one unit of speed to it and the exit one adding minus one unit of speed because of the opposite direction.

So now with one portal on the shovel and the other somewhere on a wall the shit gets accelerated and you will feel a force acting on the shovel that decelerates it's swing.

Velocity is relative and this is why it works. If velocity wasn't relative then Einstein would be wrong and many of the effects we see in the real world could never happen.

[–] Darkard@lemmy.world 2 points 1 year ago (1 children)

Nuh-uh. The gift from the rump don't make no jump

[–] haggyg@feddit.uk 8 points 1 year ago (1 children)

But even in the image example, how would that work? The people have no momentum, they wouldn’t flop out, just fall back through, and then stay half in half not. According to you, air resistance wouldn’t even push them out because as soon as it goes through the portal the air is not moving relative to the people. I think your blatant lack of respect for relativity is unnerving and gets super confusing very quickly.

[–] Darkard@lemmy.world 2 points 1 year ago

Nuh-uh. Flicking dog turds

[–] SgtSilverLining@lemmy.blahaj.zone 3 points 1 year ago* (last edited 1 year ago)

dog eggs

🤮

[–] FoxAndKitten@lemmy.world 1 points 1 year ago

I think that's a very strong argument and a great metaphor, but you forget relativity.

All reference frames are valid - you could say the Earth and the people are moving and the train is stationary, you could say the train is moving and the earth and people are stationary, or you could say they each have a vector moving around the sun or anything else

But when you travel through a portal, the only valid reference frames are you and the entry portal. Your momentum relative to the Earth doesn't matter - why would it? You can open a portal to the moon and jump through, and we see momentum is preserved. The Earth isn't a special reference frame, it's just the most noticeable one.

So let's pick the reference frame of someone on the track. Let's look through the portal and say there's a sign on the other side - as it approaches, you'd see a sign approaching you through the portal. Relative to you, through the portal the sign is moving at 30mph. The portal passes over you - you haven't moved, but you enter a new reference frame, a frame in which the Earth and everything on it is moving at 30mph