127 réponses à ce sujet

[adam_grif]

I wonder if we can get a dev to post a comment explaining things further.

[Chained_Creator]

RevengeofNewton wrote...
Physics major here.

The fail is a lot bigger than what you imagine. CoM is preserverd. It cannot not be preserved. Therefore the velocity has to increase. This means that Conservation of Energy is not preserved because the velocity cannot change to make the energy be the same.

Example:
Object mass = 2 kg
Object velocity (relative to itself) = 3 m/s

Momentum: P = mv = 2 kg * 3 m/s = 6 kg m/s
Energy: KE = .5 m*v^2  = .5*2 kg * (3 m/s)^2 = 9 J

If you change the mass to 1 kg, you get
P = 3 kg m/s
KE = 4.5 J

This cannot be. So either something else has to interact witht the system to add the missing energy or the velocity has to change. The velocity has to change to 6 m/s to keep CoM, but it has to change to 4.3 m/s to keep the CoE. An object cannot have two different velocities relative to itself at the same time. Hence, unless they actually come up with a way to add the missing energy, it is epic fail.

Could it be some sort of expansion of a Casimir cavity to preserve the CoE?

RevengeofNewton wrote...
But now let's look at things a different way. This is a video game. Even me, a physics major, does not expect a video game to be completely accurate in its dealings with the laws of physics/chemistry/etc. Bioware had a lot of things right with its physics concepts, and I think a video game company should be praised for having those things right, rather than nitpicking over a few, albeit glaring, inconsisties.

Very good for a video game. (Unlike, say, Star Trek or Star Wars. <_<)

[vashts1985]

Crawling_Chaos wrote...

adam_grif wrote...

Physics is absolute, and it's not going to change just because it's The Future ™. Nobody ever said our current understanding was complete, but if you're going to just use the argument "we don't know for sure, therefore it's all possible", then you should just leave this thread right now, because this thread is for serious discussion.

If you're just going to throw your arms up and say "well, maybe not! you don't know for sure", then we can't discuss anything at all.

Physics is absolute (aka infallible)?  I thought one of the great things about science was its ability to distance from such things so common in religion where everything is explained and absolute (unchangable, infallible).

I'm sorry to say, but you absolutely misunderstand the point of science.

physics is apsolute, our understanding of it might not be.

[Schneidend]

adam_grif wrote...

Right, because there's a mandate that says you have to read this thread?


I'd rather have oral sex with a power outlet than read another "OH TALI IS SOOOOOOOO HAWT DO YOU THINK SHE'LL BE AN LI" or "Hey gais, does cerberus network card come with standard edition?" thread.

A fair point. Carry on.

[adam_grif]

Crawling_Chaos wrote...

adam_grif wrote...

Physics is absolute, and it's not going to change just because it's The Future ™. Nobody ever said our current understanding was complete, but if you're going to just use the argument "we don't know for sure, therefore it's all possible", then you should just leave this thread right now, because this thread is for serious discussion.

If you're just going to throw your arms up and say "well, maybe not! you don't know for sure", then we can't discuss anything at all.

Physics is absolute (aka infallible)?  I thought one of the great things about science was its ability to distance from such things so common in religion where everything is explained and absolute (unchangable, infallible).

I'm sorry to say, but you absolutely misunderstand the point of science.

Palm face. Physics is unchanging and absolute. Unwavering. You can't get around it.

The only thing that changes is how we understand it. New physical theories don't coincide with a sudden change in the way the world operates around us, we just realize things that were already there before.

[Chained_Creator]

Crawling_Chaos wrote...

adam_grif wrote...

Physics is absolute, and it's not going to change just because it's The Future ™. Nobody ever said our current understanding was complete, but if you're going to just use the argument "we don't know for sure, therefore it's all possible", then you should just leave this thread right now, because this thread is for serious discussion.

If you're just going to throw your arms up and say "well, maybe not! you don't know for sure", then we can't discuss anything at all.

Physics is absolute (aka infallible)?  I thought one of the great things about science was its ability to distance from such things so common in religion where everything is explained and absolute (unchangable, infallible).

I'm sorry to say, but you absolutely misunderstand the point of science.

Math is like religion?

[Schneidend]

adam_grif wrote...

Palm face. Physics is unchanging and absolute. Unwavering. You can't get around it.

The only thing that changes is how we understand it. New physical theories don't coincide with a sudden change in the way the world operates around us, we just realize things that were already there before.

I'm pretty sure what Crawling is saying is not that new physical theories change the way the world operates around us, but that the way we THINK we understand the world around us operates may turn out to be untrue. A new technology could allow us to sidestep the rules as we understand them, or may prove an exception to those rules.

[Permutation]

I love it when people try to justify fiction on real world terms with wiki knowledge. This discussion will not benefit anyone. Oh, how I miss Cogitation.

[Chained_Creator]

Permutation wrote...

I love it when people try to justify fiction on real world terms with wiki knowledge. This discussion will not benefit anyone. Oh, how I miss Cogitation.

I get my stuff from xkcd, actually. An infinitely more respectable knowledge base. ...Maybe.

[adam_grif]

Permutation wrote...

I love it when people try to justify fiction on real world terms with wiki knowledge. This discussion will not benefit anyone. Oh, how I miss Cogitation.

Not as much as you love rolling into threads you don't approve of solely to tell people that you don't like what they're discussing. Made more delicious by it's completely voluntary nature.

I'm pretty sure what Crawling is saying is not that new physical
theories change the way the world operates around us, but that the way
we THINK we understand the world around us operates may turn out to be
untrue. A new technology could allow us to sidestep the rules as we
understand them, or may prove an exception to those rules.

Right, but it's not that simple. There's something in physics called the classical principle (or sometimes classical limit), it was a QM thing that basically says that QM has to give classical answers at classical scales. From this, you can infer something more general:

All new theories must give the same answers as old theories where the old one has been confirmed by experiment.

So think about how Newtonian physics and GR give the same answers nine times out of ten. They only start to differ on supermassive objects or ones that are traveling near light-speed. These are things Newton couldn't possibly verify by experimentation, which is why he didn't account for them.

But something like thermodyanmics, conservation of energy and so on, these are things physicists hold in high regard. In fact, your theory violating Conservation of Energy is the theoretical kiss of death - you know something is horribly wrong when you're violating it.

I'm not disputing that there is some vague metaphysical doubt about things, and I know for a fact that our understanding is incomplete (i.e. discrepancies between QM and GR is the most obvious one), but it's simply not satisfactory to say something like "well, maybe you're wrong, therefore it's possible".

Then they backpedal and say stuff like "oh, I wasn't saying that it's possible! Don't be so arrogant! They said we would never X the Y Barrier!"

It smacks of rhetoric and lacks thought.

I direct people interested in science at all to read this.

[Chained_Creator]

Crawling_Chaos wrote...

Chained_Creator wrote...

Math is like religion?

I have absolutely no idea how or where you got that from.

Uh, you said something to the effect of "things in common with religion, like being unchangable/infallable".

That's pretty much Math down to a crossed T and a dotted I. For example "4+6=10" is always true. Period. You can never contradict it without being mathematically incorrect. It is true because...it is true! 

Modifié par Chained_Creator, 22 janvier 2010 - 07:27 .

[Permutation]

adam_grif wrote...

Permutation wrote...

I love it when people try to justify fiction on real world terms with wiki knowledge. This discussion will not benefit anyone. Oh, how I miss Cogitation.

Not as much as you love rolling into threads you don't approve of solely to tell people that you don't like what they're discussing. Made more delicious by it's completely voluntary nature.

Of course it's completely voluntary. Is there any other way? Incompletely voluntary, perhaps? What's really "delicious" here is students teaching students on a game forum. This thread is a joke. This discussion is a joke. You are a joke.

Modifié par Permutation, 22 janvier 2010 - 07:33 .

[Chained_Creator]

Permutation wrote...

adam_grif wrote...

Permutation wrote...

I love it when people try to justify fiction on real world terms with wiki knowledge. This discussion will not benefit anyone. Oh, how I miss Cogitation.

Not as much as you love rolling into threads you don't approve of solely to tell people that you don't like what they're discussing. Made more delicious by it's completely voluntary nature.

Of course it's completely voluntary. Is there any other way? Incompletely voluntary, perhaps? What's really "delicious" here is students teaching students on a game forum. You're a joke.

You haven't caught on yet, have you?

[adam_grif]

Crawling_Chaos wrote...

Note how I wasn't refuting your arguments on Conservation of Momentum/Energy, nor was I arguing for the possibility of anything.

I was simply stating that you don't speak for scientists and engineers of the year 2500.

To what effect? I don't speak for the people of 2500 when I say the sky is blue, either. I've already acknowledged pages back the very, very small doubt associated with something like this. But does me not having the knowledge of the year 2500 have anything to do with whether a totally fictional, self contained universe that is Mass Effect, violates certain physical principles?

Either it does, or it doesn't. You can't just say "YOU DON'T HAVE FUTURE PHYSICS", because that's totally irrelevant to whether or not it violates CoM and CoE. We can determine whether or not it does by the information we gleam from the codex and the capabilities of the spacecraft.

If you were never disputing this (the entire point of the thread), then you were just making a comment for the purpose of being contrary and starting a heated discussion. That's the definition of trolling.

Modifié par adam_grif, 22 janvier 2010 - 07:46 .

[adam_grif]

Good night sir.

[atheelogos]

Murmillos wrote...

(I hate the new forums at times)

why?

[RevengeofNewton]

vashts1985 wrote...

RevengeofNewton wrote...

vashts1985 wrote...

Hypothetically, yes it would.

M1V1+M2V2 = (M1+M2)Vf

This is your standard equation for a inelastic collision. In an inelastic collision, 2 masses collide and stick together, becoming one mass. when 2 masses collide and stick together, the Velocity of the system decreases due to the conservation of momentum. In order to calculate how much it decreases, we have to know how much momentum exists before the collision

M1V1+M2V2 = P

therefore:

P = (M1+M2)Vf

P represents momentum:

P = MV

therefore:

MiVi = (M1+M2)Vf

or:

MiVi = MfVf

Keep in mind here, that the momentum final is still just considering an increase in mass, because of this, we can say that M1+M2 really is just some increased final mass, and our equation still holds true because due to the conservation of momentum, MV initial = MV final.

From there we can plug in some real numbers. Lets say we have a mass of 10kg
moving at 10m/s. Our mass effect field increases that mass by 10kg, making our final mass a total of 20kg.

(10)(10) = (20)Vf

100 = (20)Vf

100/20 = Vf

Vf = 5m/s


Hypothetically, if Mass Final was a decrease in mass, the same would hold true.

We have a 100kg mass moving at 10m/s. Our mass effect field decreases that mass to 50kg.

(100)(10) = (50)Vf

1000 = (50)Vf

1000/50 = Vf

Vf = 20m/s

Problem. This is not a collision. Collisions have their own mechanics. We're talking about a simple use of EZ on a moving object, which is probably the most applicable situation. The math may work out in a particular collision, but you need to remember that the math needs to work out in ALL situations.

Remember, in physics, it must applicable in all situations. Just because it works in one situation doesn't make it correct. So my point still stands. The math DOES NOT work out in the most applicable situation (a moving object). 

i dont see how the collision matters. if you look at the equation it makes sense in a collision because the math describes what happens in a collision (inelastic that is) simply put, M1V1+M2V2 is true because we have an initial momentum which has to equal a final momentum. because we have 2 objects colliding, we have to split up the initial momentum between them. consider that we have 3 objects colliding (at the same time) sticking together, moving off at a velocity. we would have to revise our original equation.

M1V1+M2V2+M3V3 = (M1+M2+M3)Vf

we could add any number of mass to that equation, and our law of conservation of momentum still holds true.

MiVi=MfVf

so what happens when we consider a one object that increases its mass?
think about that for a second, completely ignoring anything about collisions.
the only reason i chose inelastic collisions as a base (and probably over complicating the matter) is because it A. Proves the law of conservation of momentum to be true (MiVi=MfVf), and B. demonstrates an increase in mass (M1+M2)

initial momentum equals final momentum. always

how is momentum described?

P = MV

so anytime P is constant (initial always equals final) and one of its factors changes, the other will as well, inversely proportional to the change.

V = P/M

because of the law of conservation of momentum, if mass increases, velocity decreases, if mass decreases, velocity increases.

Except that there is no M2 or V2 because there is only one mass and it's velocity!

[marchse]

nice topic for discussion, but i think it was a vast subject for me to discuss..
   
www.sterling-energy.com

[Christmas Ape]

Guys? This is space opera. If the variables in your equations aren't "plot", your equation gives false answers.