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Numsgil:

--- Quote ---t is coz the momentum in the universe always shall be 0,
--- End quote ---

Momentum of the universe is undefinable:

Momentum of Universe.

Wikipedia also says:

--- Quote ---However, in curved spacetime which is not asymptotically Minkowski, momentum isn't defined at all.
--- End quote ---

--- Quote ---the momentum in a system is always 0
--- End quote ---


--- Quote ---no matter what you do, it will always be 0
--- End quote ---

Momentum for any system is defined as:

Sum of (mass_x * velocity_x)

Say I define a system with 1 mass and 1 velocity.  A ball 2 kg moving at 5 m/s.  In my system, total momentum is not 0, but 10.

Therefor, for my system, momentum is not zero.

Now, is Momentum always conserved?  Yes, assuming it's definable (see above).  That means that taken any system. the change in momentum for the system will be zero.  That assumes you take everything into account, and that you have a way to measure micro velocity.

PY's examply describes how and why Kinetic Energy is not conserved.  That's because KE is a form of energy.  Energy itself is conserved.

But the big question: is momentum itself always zero?  Most certainly not.  Shame on you for even thinking such a thing!

Numsgil:
Imagine the universe is not expanding.  That's not hard, you've done it already.

Imagine I am moving 5 m/s relative to the universe.  Now imagine I define the universe as everything except me.  The momentum of the universe would be 5m/s times its mass.  Definately not 0.

Because velocity is a relative term, the quantity of momentum isn't important.  Only the change in momentum is important.

PurpleYouko:
You are correct that the atoms in the air or water or whatever medium a moving object is in, will take on some of the momentum as the object slows but then again we aren't attempting to model every atom of the whole universe here. All we care about are collisions between balls of varying size and mass.

My whole poiint is and always has been, that it makes more sense to model Darwinbots physics on momentum rather than KE.
For one thing, momentum has a vector while KE doesn't (it actually can but it is harder to define)
It also gets a bit tricky to split KE into X and Y coordinate vectors while for momentum it is trivial.

Basicly I am just too lazy to work out the math for using KE so I substitute momentum instead.

Incidentally though, how do you explain that the universe is not only expanding but accelerating?
How does that fit in with your idea of zero momentum?
Where is the extra velocity coming from?

Come to that, how do you know that the big bang wasn't already moving at the point of exploding into a new universe? If it had been then the universe will have a significant bias in momentum in one direction so the total combined momentum in the system will definitely not be zero.
Besides which it is impossible to find a position of rest with which to compare motion so the toatal momentum of the entire system is inherantly unknown and unknowable.
You are the one who keeps going on about relativity. Check your facts before making sweeping statements that can never be proven under the physical laws that you yourself advocate.

Endy:
Would it be possible to have a collisionless mode? Not exactly realistic, but the speed would be unreal. :D


Endy B)

Numsgil:
Actually collisions have been so streamlined you'd only get like another 20% increase in speed.

But it might be worth a go.  An interesting mode to be sure.

A much faster and pointless mode would be a 'blind' mode where bots don't get any information through eyes or reference variables.  You'd have to 'feel' your way around.  Talk about unreal speed.

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