: You keep saying higher center of balance. If the context here is a humanoid
: mech that's let's say ideally proportioned, then other than physically
: being farther from the ground, the center of balance is still proportional
: to body size.

Agreed. It is possible to design a humanoid mech so that the center of gravity is the same as a human's.

: In essence, 'center of balance' isn't the issue as it's
: already relative to the body; it's having to adjust to the size of the
: machine you're maneuvering.

: But anyway, who says center of balance is
: inherently a positive or negative, IF engineering made sure the center of
: balance was in an optimal location for the mech already? CoB shouldn't be
: a problem in a good design .

It's already a problem because you have to design around it.

: I should say, when arguing feasibility of a fictional machine class which is
: only usable through space magic, it's just as unfair to say "it is
: not possible" because.. you're saying the space magic isn't possible.
: Which..is kind of a pointless argument. Space magic is space magic because
: it recognizes that to the best of our current knowledge and scientific
: discoveries, some property is (/ies are) not possible. That's why it's
: magic.

Space magic is space magic because exists without regard to rules or internal consistency.
The Mass Effect isn't space magic, because what it can do is very well defined.

: And that's why I have issue with you saying mechs cannot ever be better than
: vehicles.

I conceded earlier that there might be a few applications to which mechs have an advantage.
I'm arguing that those applications are niche, and rarely the roles that mechs are depicted in.

: Mechs are another type of vehicle. They are an ideal vehicle designed to take
: advantage of human physiology on a necessarily larger framework

Does human physiology have advantages? Oh, sure, compared to animals and simple machines, we have an advantage.

Good against the living is one thing. Good against the machine? That's something else.

If you're building a mech, why make it bipedal?
Humans are bipedal because it frees up our hands and arms. Nature seems to abhor vertebrate hexapods, which means we only have two legs to spare. As a result, our feet are much more complicated than that of, say, dogs and goats.

So, you're building a mech. You have the choice of redundant, simpler legs if you build a quadruped, or you can build a biped whose balance depends upon multiple interdependent systems.
Why bother with a biped.

Great. While I was typing this, I saw a spider walking across the floor. I had to make the choice of watching it closely to study how it moves, or not weirding out rest of the people in the room.

: - whether 1-2x a human size,

That ain't a mech. It's a guy in power armor. Unless it's a robot or a drone, like the Hammeroids in Iron Man 2.

: or a hundred fold.

Now you're pushing it.

: Your "space magic" takes
: care of the how. What you're arguing is how believable you think any
: particular space magic is - whether based heavily on current science (more
: believable, but still not possible now), or heavily in fantasy and
: imagination (wow and cool factor, definitely not possible now).

What's the difference between fictional technology and space magic?
My initial position was that space magic stretches the reader's suspension of disbelief to the breaking point. Later, I considered Arthur C. Clarke's Third Law, where 'Any sufficiently advanced technology is indistinguishable from magic."

I think the best place to put the dividing line between 'sufficiently' and 'insufficiently' is the point where we can relate to technology. Which still isn't a good definition, but it's a start.
In Halo, the UNSC has some "Sufficiently advanced technology" in the form of shields, artificial intelligence, and faster than light travel. Invariably, such technology has been depicted as rare and expensive.

: Fictional tech is magic. :P How magic seems to be the question. Some people
: like more magic, some people have a lower threshold for suspending
: disbelief. It's the stuff of nerd debates.

I believe that I said elsewhere that I don't mind mechs in some science fiction series. StarCraft, for example, has Goliaths and Dragoons. It also has psionics (Possibly one of the purest forms of space magic) and... to be honest, psionics is probably the only major offender, if only because it's so all-encompassing in the setting.

: Like debating the physics of Superman flying.

Telekinesis. Same place he gets his super-strength from.

: I'm saying why limit the possibility of what an engineer can come
: up with in a science-fiction environment?

Mostly to avert homogeneity among science fiction franchises.
While we're on that subject, can I get a science fiction universe that doesn't slavishly copy space battles from Star Wars and Star Trek?

: As they design a mech, and find shortfalls
: for a given task, they can either alter the intended task, fix the
: problem, work around the problem, or ignore the problem (bad! but
: possible; hide the weakness, hope the enemy never discovers it?).

Sweep it under the carpet. Hope it doesn't result in getting hauled before a congressional committee?

Throw a little gas onto the fire?

: See above.
: Also, a weakness in what context ? Legs aren't just "a weakness".
: A weakness in doing what task? Compared to what?

Legs have controls and motors or actuators in them. A tire doesn't. Relatively speaking, a tire and drivetrain are a much simpler linkage of machinery than a set of legs.

So, if you're operating in a setting where that vehicle will be subject to abuse, where it will not be convenient to repair, or where people's lives are relying on it performing its job without mechanical failure, you want a simple system less prone to breaking.

: http://en.wikipedia.org/wiki/Rotating_locomotion_in_living_systems

Thank you.

: Also, our blood cells are all detached from each other, swimming about and
: interacting with the physics of our body.

Apples and oranges.

: Detachment isn't an issue.

Detachment IS an issue. Let me quote from the article.

Another potential problem that arises at the interface between wheel and axle is the ability of an organism to transfer materials across this interface. If the tissues that make up a wheel are living, they will need to be supplied with oxygen and nutrients and have wastes removed in order to sustain metabolism. A typical animal circulatory system, composed of blood vessels, would not be able to provide transportation across the interface.[1][32] In the absence of circulation, oxygen and nutrients would need to diffuse across the interface, a process that would be greatly limited by the available partial pressure and surface area, in accordance with Fick's law of diffusion.[2] For large multicellular animals, diffusion would be insufficient.[6] Alternately, a wheel could be composed of excreted, nonliving material, such as keratin, of which hair and nails are composed.[6][9

: Each
: cell in the body has a task to carry out independent of all others, for
: which it's specially attuned (even if some others have identical tasks).

Except each cell is dependent upon a circulatory system* to provide nutrients and oxygen, at the very least.

*I think our corneas are a partial exception, as they take oxygen directly from the air. Still need nutrients.

: You've just explained a context in which wheels are more beneficial, and in
: which wheels are not beneficial.

And the situation where legs are more beneficial is, surprise surprise, NOT the situation we're considering. We're talking about mechanical systems, not biological systems.
If an animal was being designed and created in a lab with the express purpose of living in the wild, I would recommend designing it with legs. Unless I'm really ambitious, or we're designing a fish, etc.

: So I rest my case. (of course you'll
: point out that mechs are mechanical, and thus wheel should always been
: more beneficial?) pssh!

Yeah.
Quite simply, a machine is different from an organism. Different capabilities, different limits. The limits faced by biology make wheeled locomotion a needlessly complicated system. Doesn't mean that legs are simple for biology, but they are simpler.

: What colour is skepticism?

It's kind of a pale shade of anti-Octarine, really. That's why storytelling is so magical, because it relies on suspension of disbelief.

: Relative to the ground.
: But humans have a higher center of gravity compared to an ant relative to the
: ground. And we're both more capable than the other for certain tasks.

Size matters. So does configuration of limbs, intellectual capacity, etc.

: But you can stomp on an ant.

If it had the same mass and volume as you? Hardly.
Forgetting, of course, that it you scaled an ant up to human size, it would fall apart from bad structural optimization before it could even suffocate from a respiratory system unsuited to human-scale animals.

A better example would be, say, a boer goat. Well fed, an adult female can weigh over sixty kilos and stand slightly taller than a golden retriever at the shoulder.
Give a sixty-kilo person a shove, and they'll fall over unless they brace themselves. Give a sixty kilo boar goat a shove and it'll stare at you, wondering what you're up to. I've seen one rear-ended by a four wheeler. It's only a small exaggeration to say that the guy might as well have hit a fence post.

: Indeed.
: Another reason why I'm intrigued by Captain Worf's possible spinoff ST
: series.

Could be interesting, but I was under the impression that Paramount wasn't going to green-light any TV shows while Abrams was doing his movies. Have you heard differently?

: The term is "specialized". It's narrow, but it's specific and it's
: advantageous. Neither vehicles nor mechs have to have narrow uses. But
: perhaps that's a strength of mech styles - less versatile, but more
: potential in specialized tasks, if engineered competently.

OK, answer me a question.
What would the point be to an AA system with legs? Or a walking howitzer? Would you put a plow on one for obstacle clearance duty? Or make a mecha APC?

You are right; mechs are niche systems, suitable for a narrow and short range of applications. The problem is that, in fiction, they are never limited to those niche systems. If they aren't there for the rule of cool or serving as the first and last answer to anything on the battlefield, they're there just because... well, we've looped back to the rule of cool. Which also encompasses the "First and last answer" option.

: Hostile
: environment? Well, find a mech engineer (heck find them all) and see if
: they can come up with a mech design that is optimized for that specific
: environment, and performing a set of tasks in it.

Then get that same group of engineers, and see if they can come up with a conventional vehicle that can do the same thing with a lower manufacturing cost and a higher reliability rating.