How realistic are the small scale physics?

[phasma_phasmatis]

First of all, thank you for the game. I've already spent 19 hours playing it on steam (not unattended).

I went through all of the pre-made maps, and when I watched the "dice swarm" one, I noticed that their dimensions and the distance between them were close to real world proportions.

I also noticed that G = 1.00.

So the sim showed that a group of dice (5 cm^3), would coalesce in 1 day if they are isolated from external forces and start out not moving.

Is that really possible?

Why doesn't that happen on Earth?

[jurluk]

you already gave the answer.

So the sim showed that a group of dice (5 cm^3), would coalesce in 1 day if they are isolated from external forces and start out not moving.

Is that really possible?

Why doesn't that happen on Earth?

obviously, because of earth's gravity which is pulling dices towards center of the earth. you can's isolate from that force

[phasma_phasmatis]

you already gave the answer.

So the sim showed that a group of dice (5 cm^3), would coalesce in 1 day if they are isolated from external forces and start out not moving.

Is that really possible?

Why doesn't that happen on Earth?

obviously, because of earth's gravity which is pulling dices towards center of the earth. you can's isolate from that force

What if the dice were in free fall in a vacuum?

[Abaris]

you already gave the answer.

So the sim showed that a group of dice (5 cm^3), would coalesce in 1 day if they are isolated from external forces and start out not moving.

Is that really possible?

Why doesn't that happen on Earth?

obviously, because of earth's gravity which is pulling dices towards center of the earth. you can's isolate from that force

What if the dice were in free fall in a vacuum?

They would just fall towards the centre of gravity, although at the same speed, since they are in a vacuum.

[ChemicalBR0]

the dice would also fall at the same speed outside of the vaccumm.
as both are identical in size and shape they both have the same air resistance. (therefore the same terminal velocity.
a sphere of lead will fall at the same speed as a sphere of balsa wood of the same dimensions.
the wood is obviously lighter but both have the same air resistance.

if you dropped a hammer and a feather in a vaccumm they would fall at the same speed as you have removed air resistance.  gravity doesn't discriminate

getting back to your original question accretion does happen on earth on a much smaller scale.
dust particles will attract each other into dust balls as the minute gravtitational force given off by the particle will attract other particles. and the pull of your house will draw them into a corner of a room (just like in space) as the mass increases other factors like friction come into play and gravity can't overcome it any more.

[Joshimitsu91]

I would guess the main reason why large objects don't pull together on earth is due to friction, so i guess if you had two dice on a frictionless surface in a vacuum they would pull together under there own gravity. I might be wrong though! Plus, thats an impossible scenario anyway... i guess if the surface had less friction than the force then they could pull together but i don't know if such a surface exists

[ChemicalBR0]

such a surface does exist.
its called water

have you ever put a cup with a wet bottom on a glass table and it moves on it's own.
to my mind there is only 1 invisible force capable of such a thing and it isn't a ghost.

if you put 2 small enough items (like our dice) onto a sheet of wet ice they will attract without the need for a vaccumm.

[Joshimitsu91]

such a surface does exist.
its called water

have you ever put a cup with a wet bottom on a glass table and it moves on it's own.
to my mind there is only 1 invisible force capable of such a thing and it isn't a ghost.

if you put 2 small enough items (like our dice) onto a sheet of wet ice they will attract without the need for a vaccumm.

Thats not strictly true... the reason your cup moves is because your table is on a slant and the gravity of the Earth is moving it.

EDIT:

Also, the attractive force between two dice would be too small to overcome the friction from the surface.

[Dan Dixon]

Why doesn't that happen on Earth?

Notice how long it takes for this to happen, that's because the force of gravity between two dice is really small. You don't notice this on Earth because the the force of gravity is so small that it's easily canceled out by air resistance, surface friction, etc...

Everything with mass is pulling on everything else: the keyboard on your fingers and the chair on your body, but you don't notice it because the force is so very, very tiny. What you do notice is the huge mass beneath you: the Earth.

[Dan Dixon]

I remember seeing some science program (almost 2 years ago_ where someone said that if you had 2 dice floating in space that it would take a few hours for them to come together. That was all the inspiration I needed to try that in my software and so I made the modifications necessary for that to work.

It's also what inspired the simulation where objects are orbiting a bowling ball.

I can't remember what program that was. Does anyone know what television show had a guy that mentioned two dice floating in space? Probably something on Discovery or PBS, but I don't remember for sure.

[Puddin]

The show that you are taking about is called The Universe made by the history channel.

Here is a link to the specific footage you mentioned http://www.youtube.com/watch?v=67uw5QAtyno

 

[Dan Dixon]

Another example of the Internet being amazing.

Thank you.

And I sent a message of thanks to Gregory Laughlin, the guy in the video:
http://www.ucolick.org/~laugh/homepage.html

[scowie]

getting back to your original question accretion does happen on earth on a much smaller scale.
dust particles will attract each other into dust balls as the minute gravtitational force given off by the particle will attract other particles. and the pull of your house will draw them into a corner of a room (just like in space) as the mass increases other factors like friction come into play and gravity can't overcome it any more.

I would think that static electricity would dominate over the gravitational pull of dust grains or your house.

As for the original question, you probably could achieve the same thing on earth, provided you could isolate the objects from other forces, like static charge, vapour pressure and of course, friction.  But that would be easier said than done.

[atomic7732]

Another example of the Internet being amazing.

Thank you.

And I sent a message of thanks to Gregory Laughlin, the guy in the video:
http://www.ucolick.org/~laugh/homepage.html

That's the systemic guy!

[Dan Dixon]

And I sent a message of thanks to Gregory Laughlin, the guy in the video:
http://www.ucolick.org/~laugh/homepage.html

And he replied. He was very gracious.

[Darvince]

Its infinite. The gratitute of everything combined. Also aren't small scale physics usually realistic in things like these until you get to something ridiculously low?

[atomic7732]

And I sent a message of thanks to Gregory Laughlin, the guy in the video:
http://www.ucolick.org/~laugh/homepage.html

And he replied. He was very gracious.

I sent him a message about Systemic and he never replied. lol

Its infinite. The gratitute of everything combined. Also aren't small scale physics usually realistic in things like these until you get to something ridiculously low?

Around picometers, yeah, where the weak and strong forces take over.