[_ Old Earth _] The origins of the universe

[Featherbop]

Ok you were just pointing out something then.

 

[saved4life]

Ok you were just pointing out something then.

Right.

 

[Featherbop]

i is r teh smrat

 

[victorhadin]

Then what about the second law of thermodynamics?

*Sigh.*

I honestly don't know why people keep trotting that one out. I am too tired to give you the standard heat engine statements of the 2nd law and it's connections to entropic increase, or to give the definition of entropy right now, but let me tell you that it is a frequently misunderstood relationship. Entropic increase is not an 'increase in disorder' per se, though it is frequently described as such in oversimplified fashions and from the perspective of momentum on the particulate scale, it is so.

However entropic increase says nothing to contradict the formation of galaxies or the evolution of complex structures. I can go over this in more detail some other time if you wish, but you could also just go and read a good text on basic thermodynamics and fluid dynamics, which will go over it quite adequately.

 

[Barbarian]

I would be pleased to hear an explanation of how highly complicated structures like hurricanes are forbidden by the 2nd law.

Any takers?

 

[evanman]

How did bumble bees ever evolve?

 

[Barbarian]

How did bumblebees evolve? From simpler hymenopterans. Bumblebees are relatively primitive bees, actually.

 

[evanman]

Doesn't evilution teach "Natural Selection"?

Bumble Bees shouldn't be able to fly, according to scienctific laws!

 

[victorhadin]

Doesn't evilution teach "Natural Selection"?

Bumble Bees shouldn't be able to fly, according to scienctific laws!

Yeesh, do people still honestly believe this?

This rather enduring modern myth was brought forward by over-simplistic viscous aerodynamic calculations upon bumblebee flight. The oversimplicity of the methods used led to the ridiculous assertion that bumblebees 'coud not fly' (much the same way that an oversimplistic analysis of, say, a kangaroo's bouncing would lead you to conlude that it does not eat enough to keep on doing so).

In fact, what occurs over bumblebee wings in flight is a stable vortex system that feeds the flow over the wings, caused by their complex flapping. This vortex lowers surface pressure over the wings, stabilises the flow and helps prevent flow separation. It also helps adjust for the horrifically low Reynolds-number flow found over bumblebee wings, which would otherwise, naturally, be far more prone to separation and resultant loss of lift and pressure drag, among other things.

Hence; they can fly. Another handy example of the scientific method encouraging further study when obviously dodgy results turn up; in this case due to oversimplistic analysis by (bored?) aerodynamicists.



The bee does not need to know all this, fortunately for it. It just flaps it's wings as instinct and experience instruct it.

 

[Barbarian]

Victor, I think our friend is referring to a study done by an engineer, who plotted the energy requirements and inputs, and concluded that a bumblebee could not fly.

Like Kelvin's "proof" that Darwin was wrong, the numbers were right, but the assumptions were wrong. Inside the bee, there's a small pad of resylin (a biological rubber chemically similar to, but even more efficient than elastin) under each wing hinge. As you hinted, the bee recovers almost all of the energy from the downstroke from the compression and release of resylin.

Hence, the bumblebee flys just fine, thanks to the evolution of efficient materials.

And the Barbarian is pleased to know all those courses in entomology were not wasted.

 

[victorhadin]

Well that sure shows my bias, approaching it from an aerodynamic point of view.

The induced vorticity thing is also true, mind. I was not aware of the resylin. You learn something new every day.

 

[Barbarian]

Both effects are discussed in Steven Vogel's excellent work on biomechanics, Life's Devices". He has a follow-up called Cat's Paws and Catapults that is also quite good.

If you think Reynolds Numbers pose a problem for bumblebees, consider bacteria. For them, motion in water is like swimming in warm tar!

 

[Pearly Gator]

Both effects are discussed in Steven Vogel's excellent work on biomechanics, Life's Devices". He has a follow-up called Cat's Paws and Catapults that is also quite good.

Cat's Paws and Catapults.... Is he the guy that came up with this?

 

[evanman]

Inside the bee, there's a small pad of resylin (a biological rubber chemically similar to, but even more efficient than elastin) under each wing hinge. As you hinted, the bee recovers almost all of the energy from the downstroke from the compression and release of resylin.

Hence, the bumblebee flys just fine, thanks to the evolution of efficient materials.

I wonder what these "efficient materials" were that these insects had?

Do we have any evidences of any simpler hymenopterans existing before Bumble bees? When did bumble Bees first appear and their ancestors disappear?

 

[Barbarian]

I wonder what these "efficient materials" were that these insects had?

It's kinda similar to elastin, which we have. A bit evolved from ours, of course.

Do we have any evidences of any simpler hymenopterans existing before Bumble bees?

Yes. Bees represent one of several highly evolved lines of hymenopterans. There are much more primitive ones, such as the ichnumen wasps, who use what will eventually become a sting as an ovipositor.

When did bumble Bees first appear and their ancestors disappear?

In the Cretaceous, and we still have many of those primitive hymenopterans around today.

 

[victorhadin]

Both effects are discussed in Steven Vogel's excellent work on biomechanics, Life's Devices". He has a follow-up called Cat's Paws and Catapults that is also quite good.

If you think Reynolds Numbers pose a problem for bumblebees, consider bacteria. For them, motion in water is like swimming in warm tar!

Now you mention that... ouch! :o

 

[Barbarian]

(Barbarian discusses "Cat's Paws and Catapults)

Cat's Paws and Catapults.... Is he the guy that came up with this?

Nope. That appears to be a slingshot. This is a catapult:

Catpults historically depended on torsion of an elastic substance like sinew or hair. Slingshots were impractical, due to the lack of a useable elastic with good strain/stress numbers. They were often used as field artillery for close support of troops. Typically, they were used to blast holes in the front lines of an advancing force.

This is a trebuchet:

It depends on a huge weight on the short arm of a 1st class lever. The weight, when released, moves a short distance slowly, but the missile, in the sling, moves rapidly, and is thus propelled a considerable distance. This was the "Heavy artillary" of medieval armies. They were usually used for sieges, to knock down stonework.

This is a ballista:

It used either a large bow, or torsion to toss a large spear-like projectile. Not as useful as the others for most purposes, it was often used in ancient navies, because it was good at putting a lot of force on a small area.

 

[evanman]

we still have many of those primitive hymenopterans around today.

Seems to me that if the above is true, then why don't we find any other man-apes around today?

 

[Barbarian]

That would be like asking why, if there were once many kinds of horses, only one genus is left in the world. Extinction happens.

However, we do have some cousins. Chimps, for example, are also descended from earlier apes that also gave rise to us.

Most likely, other kinds of humans found it impossible to compete with our particular species. It didn't mean hostility or warfare; most likely we were just a lot better at exploiting available resources.

 

[willow the wip]

However, we do have some cousins. Chimps, for example, are also descended from earlier apes that also gave rise to us.

So where are you decended from the baboons lol

There is no evedentual reason that we are decended from other animals other wise was adam and eve apes i think not.