This is getting weird, I need input.

I am on a forum simply stating Theory is not final, this is why we should be skeptical and continue to challange it even though they are yet to be disproved. Somehow it went into a debate on something I have no idea what's going on. I need some confirmation on this. What's your thought about Theory.

IMO, Theory is simply not perfect. It is waiting to be challanged and refined. It is not as firm as fundamental laws. Both can be challanged, but, theory is weaker to withstand challanges.

What's your thought on this?

I think you're right:  a theory is the best explanation that we currently have which has supporting evidence.

Wikipedia has a nice list of theories that were superseded.

Herbie

Dr Herbie said:

I think you're right:  a theory is the best explanation that we currently have which has supporting evidence.

 

Wikipedia has a nice list of theories that were superseded.

 

Herbie

 

Thanks man, I really needed that.

Just watched a documentairy on the BBC about the history of power. Was an interesting bit about the steam engine. People used it for 200 years before they understood the theory.

Nowadays we take the theory for fact and we forget to check the theory afterwards.

Same with the plane. For years scientist thought that the wind over a wing created a vacum beneath the wing. This vacum would generate lift. Recently that theory has been ditched. A wing just bends air, the direction on the bending results in an opposite force (lift). That's why at slower speeds they extend flaps to make the wing bend the air even further.

Theory is all good and well, but practise is what we deal with on a day to day basis.

Maddus Mattus said:

Just watched a documentairy on the BBC about the history of power. Was an interesting bit about the steam engine. People used it for 200 years before they understood the theory.

 

Nowadays we take the theory for fact and we forget to check the theory afterwards.

 

Same with the plane. For years scientist thought that the wind over a wing created a vacum beneath the wing. This vacum would generate lift. Recently that theory has been ditched. A wing just bends air, the direction on the bending results in an opposite force (lift). That's why at slower speeds they extend flaps to make the wing bend the air even further.

 

Theory is all good and well, but practise is what we deal with on a day to day basis.

Makes you wonder what we'll know about quantum stuff in say, 50 years from now. We would probably go "oh darn..." hehhe...

Maddus Mattus said:

Just watched a documentairy on the BBC about the history of power. Was an interesting bit about the steam engine. People used it for 200 years before they understood the theory.

 

Nowadays we take the theory for fact and we forget to check the theory afterwards.

 

Same with the plane. For years scientist thought that the wind over a wing created a vacum beneath the wing. This vacum would generate lift. Recently that theory has been ditched. A wing just bends air, the direction on the bending results in an opposite force (lift). That's why at slower speeds they extend flaps to make the wing bend the air even further.

 

Theory is all good and well, but practise is what we deal with on a day to day basis.

Oh good. That whole "makes the air go faster over the top" thing never made much sense to me.

But have we figured out how sailing works yet?

Massif said:

Maddus Mattus said:

*snip*

Oh good. That whole "makes the air go faster over the top" thing never made much sense to me.

 

But have we figured out how sailing works yet?

No, but bumblebees definitely can't fly, according to the maths.

Herbie

Massif said:

Maddus Mattus said:

*snip*

Oh good. That whole "makes the air go faster over the top" thing never made much sense to me.

 

But have we figured out how sailing works yet?

Actually, that whole "makes air go faster over the top" thing is still true. It's the "equal transit time" explanation that's been thoroughly debunked. But pressure differential caused by Bernoulli's principle is still part of what generates lift, along with Newton's laws.

EDIT: The most hilariously confusing (and wrong) explanation ever given about lift can be found at around 4:15 in this video:

Seriously funny stuff.

Massif said:

Maddus Mattus said:

*snip*

Oh good. That whole "makes the air go faster over the top" thing never made much sense to me.

 

But have we figured out how sailing works yet?

Yes, sailing works on the principle that you catch air in a cloth.

The energy of the moving air then gets transferred to the sailing boat.

Together with a counter force of the boats keel/sword against the water the resulting force is a forward force, instead of sideways.

I would draw you a picture if I could, but post in ink doest work anymore

Sven Groot said:

Massif said:

*snip*

Actually, that whole "makes air go faster over the top" thing is still true. It's the "equal transit time" explanation that's been thoroughly debunked. But pressure differential caused by Bernoulli's principle is still part of what generates lift, along with Newton's laws.

 

EDIT: The most hilariously confusing (and wrong) explanation ever given about lift can be found at around 4:15 in this video:

 

Seriously funny stuff.

Basically the principle is, if you throw matter away from you, it results in an equal force in the opposite direction.

The engine suck in air and expel that at, creating an equal force in the opposite direction. When the airplane moves fast enough, the wings bend the air flowing over them downward creating an opposite force upwards. That force helps, but is not neccesairy for flight, if you have a big enough engine. That's the principle thrust vectoring relies on. If you create a large enough force, you dont need lift.

The bigger the wing, the more air you can bend. I don't exacly understand how the curving of the wing comes into play.

Maddus Mattus said:

Sven Groot said:

*snip*

Basically the principle is, if you throw matter away from you, it results in an equal force in the opposite direction.

 

The engine suck in air and expel that at, creating an equal force in the opposite direction. When the airplane moves fast enough, the wings bend the air flowing over them downward creating an opposite force upwards. That force helps, but is not neccesairy for flight, if you have a big enough engine. That's the principle thrust vectoring relies on. If you create a large enough force, you dont need lift.

 

The bigger the wing, the more air you can bend. I don't exacly understand how the curving of the wing comes into play.

Yes, that's part of it. But so's Bernoulli's principle. Some people (I'm not saying you're one of them) seem to believe that because the equal transit time explanation is wrong, Bernoulli's principle itself is wrong or doesn't apply to how wings generate lift. But that's not true. Bernoulli's principle works and is part of how aircraft generate lift. It's just the equal transit time part of the explanation that's wrong. What you're saying is also part of it, but not the only part. It's really quite complicated.

Sven Groot said:

Maddus Mattus said:

*snip*

Yes, that's part of it. But so's Bernoulli's principle. Some people (I'm not saying you're one of them) seem to believe that because the equal transit time explanation is wrong, Bernoulli's principle itself is wrong or doesn't apply to how wings generate lift. But that's not true. Bernoulli's principle works and is part of how aircraft generate lift. It's just the equal transit time part of the explanation that's wrong. What you're saying is also part of it, but not the only part. It's really quite complicated.

Ah,.. but,..

If the air is moving at the same speed, there is no pressure difference according to the law.

Complicated? Not really, if it was complicated, we would not have so many planes!

Sven Groot said:

Maddus Mattus said:

*snip*

Yes, that's part of it. But so's Bernoulli's principle. Some people (I'm not saying you're one of them) seem to believe that because the equal transit time explanation is wrong, Bernoulli's principle itself is wrong or doesn't apply to how wings generate lift. But that's not true. Bernoulli's principle works and is part of how aircraft generate lift. It's just the equal transit time part of the explanation that's wrong. What you're saying is also part of it, but not the only part. It's really quite complicated.

So the pressure difference comes from something else? Like turbulence under the wing?

Gah... I could look something up, but I'm supposed to be pretending to work.

Massif said:

Sven Groot said:

*snip*

So the pressure difference comes from something else? Like turbulence under the wing?

 

Gah... I could look something up, but I'm supposed to be pretending to work.

/waves hand in Jedi fashion

There is no pressure difference

/waves hand at boss in Jedi fashion

I am working!

Maddus Mattus said:

Sven Groot said:

*snip*

Ah,.. but,..

 

If the air is moving at the same speed, there is no pressure difference according to the law.

 

Complicated? Not really, if it was complicated, we would not have so many planes!

Things can be complex, but that complexity is not required to use it. 

You can predict the motion of the planets very easy with a high level of accuracy with Newton's law of universal gravitation, but to actually understand what's really going on you need general relativity.

Maddus Mattus said:

Sven Groot said:

*snip*

Ah,.. but,..

 

If the air is moving at the same speed, there is no pressure difference according to the law.

 

Complicated? Not really, if it was complicated, we would not have so many planes!

If the air is moving at the same speed, there is no pressure difference according to the law.

But it doesn't move at the same speed. The air above the wing does in fact move much quicker than the air at the bottom. The only thing I'm saying it that this is not, as many people mistakenly believe, because the two air streams must take the same time to get to the end of the wing. In fact, the air stream above the wing moves much quicker in reality than the idea of equal transit time would suggest.

Exactly why the air above the wing moves faster I don't know. But I know that it does.

Just read the Wikipedia article already: http://en.wikipedia.org/wiki/Lift_(force)