Split Thread The validity of classical physics (split from: DWFTTW)

[Clive]

I have another one, Clive. 'What is the difference between a Raven and a Writing Desk?

Clive is almost an anagram of Alice, so perhaps "How are a raven and a writing desk alike?" would be more correct? Or was your error deliberate?

Anyway,the laminar flow is different in each case, Clive. It is an indicator that something is wrong. Here we go.
<snip>

I tried to follow what you wrote humber. I really did. But the further I read, the more off track you went. I have no idea what point you were trying to make with the comments about belt speed needing to follow the windspeed. What did you mean by follow? If the car is running on a belt in a tunnel in such a way that the car is always kept stationary w.r.t. the whole tunnel, then the belt speed under the car must be exactly the same value as the speed of the car over the real road for the situation we are trying to model in the tunnel.

After that you can arrange for the wind tunnel to blow air at the speed that matches the apparent wind felt by the car in the real world situation. By apparent wind, I mean the combined effect of any weather generated wind (air mass moving relative to ground) plus the effect of the car moving and thus generating its own "wind". For example, for a car driving at 100 mph over the road into a weather generated 10 mph headwind, the apparent wind felt by the car is a 110 mph headwind. If the belt and car are also on a turntable arrangement of some kind then you could simulate an apparent wind that was not necessarily an exact head or tail wind by placing the car and belt at the appropriate angle to the airflow generated by the tunnel. Note again that airflow through the tunnel needs to be at the speed of the apparent wind felt by the car in the real world situation that we are modelling. For a car(t) going downwind at exactly the speed of the wind, the apparent wind felt by the car is nil. Hence no airflow through the tunnel, and this is why spork and JB's cart on a treadmill sitting in room is just as good as a wind tunnel. The wind in the tunnel is the apparent wind felt by the car(t).

In all cases, if you get all the basic differences in velocity set up correctly, then everything else follows, laminar flow included. The only discrepancies we might expect are the mostly very minor effects from the size of the tunnel, size of the belt, and so on.

 

[humb]

Yes, but how did you like this pure humber concentrate:

When the cart he is to the area, if wheels to key have been closed, he will put himself to the back in functioning to and he will feel himself tailwind. S/he leads to front with the speed of the area, nobody will ventilate himself to feel. This is exactly analogous to the travel to the speed of wind. The consequence of the area, or the way, to the air himself and in both cases are such as he are predominated of the cart.

You'd never get humber this pure on the street, and you'd best not take it straight.

This proves the fallacy of the "frames" argument. Even you would not disagree with the original text, and I changed it to a different "frame" courtesy of babelfish: English=>Greek=>French=>Dutch=>English. The same thing happens with your cart on the treadmill. Your results are just that. The vodka is strong, but the meat is rotten.

As to Ynot's broken record player, it is merely a Coriolis concentrator, nothing more. Take it to the opposite hemisphere and see which way it spins. Either that, or a spatial karma turbulence vortex.

 

[spork]

As to Ynot's broken record player, it is merely a Coriolis concentrator, nothing more. Take it to the opposite hemisphere and see which way it spins. Either that, or a spatial karma turbulence vortex.

Yes, this seems intuitively obvious to even the most casual observer, but how can you be sure it doesn't also act as a centrifugal force rectifier, or perhaps it exploits the energy it extracts from gyroscopic precession? Why does Coriolis always get all the glory for misunderstood phenomena?

 

[mender]

Coriolos would be flushed with pride at the frequency of usage given to his contribution to physics!

 

[humber]

Yes, this seems intuitively obvious to even the most casual observer, but how can you be sure it doesn't also act as a centrifugal force rectifier, or perhaps it exploits the energy it extracts from gyroscopic precession? Why does Coriolis always get all the glory for misunderstood phenomena?

Taking in humb's laundry now.

ETA:
Too bad precession is a force and not an energy.

Mender, I have the sinking feeling that was a pun.

 

[sol invictus]

Too bad precession is a force and not an energy.

Well done - that's a very good one! One of your best not-even-wrong humberisms in a while.

 

[mender]

Mender, I have the sinking feeling that was a pun.

Yes, but not one of my better ones. So far I've snuck nine more into my posts hoping to trigger a response; thankfully you've saved me from having to say "no pun in ten did".

 

[spork]

Taking in humb's laundry now.

I don't know what that means. But humb entertains the hell out of me. You're hit and miss.

Too bad precession is a force and not an energy.

It's good to know you're still batting 1000 when it comes to being wrong. Precession is not a force or an energy. It describes a motion.

EDIT: D'OH!!! Sol beat me to it. I propose we dedicate the next 20 pages to debating what precession is.

 

[humber]

Clive is almost an anagram of Alice, so perhaps "How are a raven and a writing desk alike?" would be more correct? Or was your error deliberate?

Yes, Clive, it was posed to me that way, but 'alike' is perhaps better.

I tried to follow what you wrote humber. I really did. But the further I read, the more off track you went. I have no idea what point you were trying to make with the comments about belt speed needing to follow the windspeed. What did you mean by follow?

It's about the way the belt's function is derived, Clive.
The wind and road are certainly connected in the real world, and part of a physical system, so it can be said that the wind blows over the road for example. That real wind is present in the BMW setup. It is a literal copy of the wind.
However, the car's relation to the road is determined by the motion over it, but of course, the car is actually no moving. This means that the belt is not a real model in the sense that the wind is.
The system is in part real. The wind is a good physical representation of air over ground, but as the car is not actually in motion, the road (belt) is artificial.
To make good the simulation, the belt and wind speeds must be equal and opposite, but could be erroneously set to reach one of the absurd situations I mentioned.
I used this idea to try and show the banality of the error that is within the treadmill. When there is no wind, the belt has no meaning. It becomes a car with its wheels spun by a belt. That's it.
The same goes for the cart in wind. No wind, big problems. The way that it goes "up" the belt lends an impression, and the ready acceptance that a belt can be like road, makes for a convincing display, but that is it.
This is why you do not see real tunnels, no matter how sophisticated, that do not have real wind. In the treadmill, the energy source is also wrong, it cannot come from the belt, but must come from the wind. Relative velocities are not enough.to do that.

This is the nub of it, Clive. Once you realise that, the remainder are details.
It is difficult to see the error, and it seems, really hard to explain.
Like the 'plane on the treadmill', and the 'Monty Hall' problem, the problem is conceptual. I will answer the other questions, but this is the key, Clive.

 

[humber]

I don't know what that means. But humb entertains the hell out of me. You're hit and miss.

One court jester may amuse another.

It's good to know you're still batting 1000 when it comes to being wrong. Precession is not a force or an energy. It describes a motion.

Do you think that something about a gyroscope generated that motion, or does precession just 'kinda mosey on down'? The GWB of aero.

EDIT: D'OH!!! Sol beat me to it. I propose we dedicate the next 20 pages to debating what precession is.

He would, for more reasons than one.

 

[humber]

Well done - that's a very good one! One of your best not-even-wrong humberisms in a while.

Why is it that you post only when you have something petty to say?

I stick with my answer regarding precession, despite your remark to the contrary.

Let's see if we can't give you someting to keep you occupied. I say that you, personally, cannot refute my argument that the cart is going the wrong way.
Do you think that fact may have something to do with the "bad intuitions" of those professors, who declare the treadmill to be nonsense?

 

[ArmillarySphere]

I do sometimes find facts to be disagreeable.

This is obvious.

(a canoe floating down a river does *not* leave a bow wave.

Please state why not.

No, here's where you're wrong. There is no "why" - this is a plain statement of fact. Any theory that tries to explain it must come after that we've established what the facts actually are.

I've seen this with my very own eyes, multiple times. If you really want to convince anyone that you're correct (as opposed to just venting steam on an internet board), go out and toss a few things into a stream and snap some pictures/video. Once you've done that, we can discuss what theories correctly predict this behaviour. But only once we have agreed on what the behaviour is.

(humber thinks a cart going downwind feels a forward ground draft while at windspeed, while a cart on a treadmill feels it going backwards)

Yes. I do believe that is one of the actual differences between real and treadmill.

And once again, you're not simply wrong on theory, but the actual fact.

A cart going downwind at windspeed in a real wind feels the ground draft going backwards, and nothing else. To test this, go out on a day with a moderate, steady draft with a friend, and have him drive until you are at windspeed (put a streamer on the antenna or something). Then lean out and feel which way the wind goes near the ground. Better yet, carry an anemometer on a stick and record the variation.

In short, you're catching up with the slower-moving air near the ground, and so you'll feel it going backwards relative to you. This is exactly the same way the cart on the treadmill will experience things.

Here's another fun fact: The cart going downwind at exactly windspeed is not driven by the wind, but by its wheels and the fan attached to them.

 

[humber]

This is obvious.

Obvious = You don't know, but hope I won't either.

(a canoe floating down a river does *not* leave a bow wave.
No, here's where you're wrong. There is no "why" - this is a plain statement of fact. Any theory that tries to explain it must come after that we've established what the facts actually are.

That is your assumption, not empirical evidence.

I've seen this with my very own eyes, multiple times. If you really want to convince anyone that you're correct (as opposed to just venting steam on an internet board), go out and toss a few things into a stream and snap some pictures/video.

Perhaps the bow wave is smaller than you think, and much of it is below the
water line. Do you know that even tiny insects create bow waves? Some use them to get about. They seem to know more than you do.

Once you've done that, we can discuss what theories correctly predict this behaviour. But only once we have agreed on what the behaviour is.

I don't think you have discussion in mind.

(humber thinks a cart going downwind feels a forward ground draft while at windspeed, while a cart on a treadmill feels it going backwards)

Thanks for the update on what I think.

And once again, you're not simply wrong on theory, but the actual fact.

If that pleases you.

A cart going downwind at windspeed in a real wind feels the ground draft going backwards, and nothing else.

How does a mass flow that is going forward become reversed when you put a cart in it? Laminar flow moves somewhat slower, but not backwards. If a car driving parallel to you slows, is it going backwards? May be to you, if you want to think in such a way, but not w.r.t the road. The cart and laminar flow have the road in common, don't they? You have to agree.

ETA:
Isn't the belt already going backwards? You are not counting your chickens twice are you?
In the wind ,the laminar flow may be thought of as coupled to the road, but not the wind above it. It seems that that the "wind" that quite clearly (vid #7) moves with the belt, moves in opposition to that upper wind.

To test this, go out on a day with a moderate, steady draft with a friend, and have him drive until you are at windspeed (put a streamer on the antenna or something). Then lean out and feel which way the wind goes near the ground. Better yet, carry an anemometer on a stick and record the variation.

Yes, and?

In short, you're catching up with the slower-moving air near the ground, and so you'll feel it going backwards relative to you. This is exactly the same way the cart on the treadmill will experience things.

No, you are traveling through a flow. What you feel is the differential velocity between your hand and what ever air is around it. Without a second reference measurement, it is not possible to separate which is "laminar flow" and which is not. I understand the molecules do not have name tags, but even still none go backwards.

Here's another fun fact: The cart going downwind at exactly windspeed is not driven by the wind, but by its wheels and the fan attached to them.

That is funny. It will still run when the wind stops?

 

[John Freestone]

Amazing!After several weeks and hundreds of posts, it looks like he's finally getting it!


But no! Once again, he changes frames of reference, and thinks that it shows that the treadmill, not he, is wrong.

I know! I pointed that out to him. But in response he said you can blow air with an air ram, or use a doppler radar, and the treadmill is a slice of time and, best of all, flow has a past and future, so ner. That's got to be one of my favourite longer quotes from humber now: "If you imagine that you are being dragged back with the belt "wind on back" then yes, you will get a laminar flow coming from behind you, but there is also one coming towards you from the belt, dragged by the belt, towards you." Cripes alive.

 

[John Freestone]

F1 cars do not use treadmills in this manner.

Well I said I was wrong, taking your word for it, but I feel ok now, thanks. I now suppose they probably do, and would find a link if I went on to the third google page of results for "motor racing testing treadmill". Anyway, these guys do. Maybe you should email them and ask them if they know the treadmill is going the wrong way.

 

[humber]

I know! I pointed that out to him. But in response he said you can blow air with an air ram, or use a doppler radar, and the treadmill is a slice of time and, best of all, flow has a past and future, so ner.

You don't think flow has a past and future, John? Nothing upstream or downstream in a river?

Perhaps you would like to stop gossiping and answer some questions relevant to the mentioned post? I put this to Spacediver.
-----
You are driving in your car, and you put your hand out of the window and feel the air. The speedometer says 50kph. You now arrange a fan or some other device to slow the wind passing over your window. If you now put your hand out and "feel" 10kph, do you ignore your speedometer and the car ahead as evidence to the contrary?
If you now shut out that information, do you believe the wind? Perhaps if you knew of the fan, no, but if it were to be done without you "knowing" it, would you then believe it, and of what use would that be?

So what do you think, John? You know I will answer in the same way as you respond.

 

[humber]

Well I said I was wrong, taking your word for it, but I feel ok now, thanks. I now suppose they probably do, and would find a link if I went on to the third google page of results for "motor racing testing treadmill". Anyway, these guys do. Maybe you should email them and ask them if they know the treadmill is going the wrong way.

Maybe you would like to support that, John, rather than wait for me to find out that they areyet again, not like the treadmill.

ETA:
That link was posted much earlier by Micheal_C, and rebutted. Next!
The original BMW shot I said was likely not to be representative of the real thing. A photographer's fantasy. The video confirmed what I said, and the means of staying it.
It works as I described. Why would you need a 300kph fan, when you could just turn up the beltspeed?

 

[John Freestone]

You'd never get humber this pure on the street, and you'd best not take it straight.

But humber on the street isn't anything like humber on the treadmill. Humber on the treadmill is going the wrong way.

 

[sol invictus]

Let's see if we can't give you someting to keep you occupied. I say that you, personally, cannot refute my argument that the cart is going the wrong way.

You want me to refute your moral judgment of the cart's motion?

Do you think that fact may have something to do with the "bad intuitions" of those professors, who declare the treadmill to be nonsense?

No.

 

[John Freestone]

Perhaps you would like to stop gossiping and answer some questions relevant to the mentioned post? I put this to Spacediver.

Gosh, I'm intruiged as to what Spacediver's answer might have been. Mine will be forthcoming if you can phrase the question in a scientific manner, or just a manner that is a lot less meaningless, assuming I'm still around by then.

-----
You are driving in your car, and you put your hand out of the window and feel the air. The speedometer says 50kph. You now arrange a fan or some other device to slow the wind passing over your window. If you now put your hand out and "feel" 10kph, do you ignore your speedometer and the car ahead as evidence to the contrary?
If you now shut out that information, do you believe the wind? Perhaps if you knew of the fan, no, but if it were to be done without you "knowing" it, would you then believe it, and of what use would that be?

So what do you think, John? You know I will answer in the same way as you respond.