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

[humber]

I agree. Even trying to hammer out a test to perform on your treamill was the same. He has to add clauses or object to clauses, to see how far he can get away from his original proposition. The same happened with asking Drela for his opinion before. It doesn't matter whether they're a living legend or a dead one, they can't win. Humber wins. That is the game.

I have no intention of funding your ignorance. I did not raise the challenge. If you can't meet it on your own terms, then you should stop being so noisy.
It is simple enough.
ETA;
Another straw man to avoid answering the other matters, Walter Mitty.

 

[jjcote]

It appears that humber has indeed ignored my quiz about the Japanese baseball gun, so spork is right again. Not surprising.

In real wind, the smoke from a flare placed on the road some distance ahead, will flow with the appropriate velocities for both the driving and boundary flows.
Traveling along that road, towards that flare, would mean that you would run into that smoke sometime in the future. But what happens if both the smoke and cart are exactly at windspeed? The smoke would always be ahead of you, except for the fact the laminar flow is slower, allowing you to gain on it. The relative or apparent speed of that flow when you catch up to it, may be small. It may just drift by.

This is not what happens on the belt. Smoke from the future, would pass by you, at full essentially windspeed, in the opposite direction no matter what. This is partly due to a nest of errors, but also because there is no 'distance' on the belt. Motion is seen as velocity or displacement but the two never meet.

Okay, we have a smoke generator sitting on the ground. There is a 10 m/s wind blowing out of the south, and we are approaching the smoke generator at 10 m/s, northbound (i.e. at windspeed) in some sort of conveyance (not necessarily wind powered). When we are 10 m from the generator, it emits two puffs of smoke, one at eye level, the other at ankle level. What do we see? The puff that is at eye level travels northward at 10 m/s, and remains 10 m in front of us, while the one at ankle level, in the boundary layer, moves forward at only 6 m/s, so we close the distance to it at 4 m/s, and we pass by it in 2.5 seconds.

Now we have a smoke generator attached to a (sufficiently large) treadmill belt that is moving from north to south at 10 m/s. It is in a room with still air, and we are maintaining our position with respect to that air (and to the "floor") by moving relative to the belt at 10 m/s in some sort of conveyance, so the smoke generator is coming toward us at 10 m/s. When the smoke generator is 10 m in front of us, it emits two puffs of smoke, one at eye level, the other at ankle level. What do we see? The puff that is at eye level stays put relative to the air (and to the "floor"), and remains 10 m in front of us., while the one at ankle level, in the boundary layer, is dragged back by the belt at 4 m/s, and we pass by it (or it passes by us) in 2.5 seconds.

Exactly the same.

 

[Clive]

Nope. A belt is not road. Take that from the treadmill, and where's your wind tunnel, Clive? So, it is relevant after all.

What? I should take the belt off my treadmill and then my wind tunnel might disappear? So the wind tunnel can only be relevant because of a belt (on a treadmill) inside it? Have I got that right?

Anyway, please, just carefully read Brian-M's post again Humber, instead of just closing your eyes (and mind) and continually shooting from the hip.

I think you will find that his wind tunnel on the truck has no treadmill or other moving belt in it. You appear to have misinterpreted his description by assuming he meant there was a treadmill inside the wind tunnel and so on. Start again. Just allow for a solid flat floor on the bottom section of the tunnel. The cart can then be tested by placing it, heading downwind, on the floor of the wind tunnel at whatever speed we want to look at. After that it can move freely just like the same cart on the "real ground" in the "real wind". In other words, the wind tunnel is only there to produce a nice steady wind (and we're starting with that wind tunnel perched on top of a truck that is parked - thus not moving relative to the ground).

 

[Clive]

The real wind diagram contains the same level of approximation that is used in the treadmill diagram. That is enough.
Do it for 1 or 10mm. Same result. Plot values in between. Same result.

What I get is the "same result" for the "reverse vector" in both real world and treadmill diagrams Humber, not the "same result" as you.

Looking again at your diagram, I see that you've already noted the relative speeds at the top and bottom of the boundary layer profile. So, let's look at your own values for the very top part of the boundary layer. For the real world you show this as 10 m/s (to the right). For the treadmill you show that same part as 0 m/s (because you're using a different datum). Now those values match the velocity of the non-boundary layer air above that point and that produces a null "reverse vector" in both cases. Lets imagine we've dipped slightly lower into the boundary layer, so now the speed for the "real word" version has dropped from 10 m/s to 9.9 m/s (and still to the right obviously). In the treadmill case, the slight dip down takes us to air that is moving around 0.1 m/s to the left. Not 9.9 m/s! Put the correct values in to start with and you get the correct values out at the end also.

The liner example is a another reiteration of the hobo in a car. Already covered by other posts.

Are you now claiming to be a mind reader Humber? My liner post was simply the first stage in the a set-up for a thought experiment. I even told you to put aside any fears that I was resurrecting the hobo on the train. Still, I imagine you must be feeling overloaded. So, I'll hold off on the liner for now, while you give Brian-M's "stages on a truck" scenario a bit more thought. At least that is what I hope you'll do, even if my expectations are different.

 

[Tunny]

I think Humber's last rant was finally too much for me. I've got to pull myself away from this train wreck before my sanity is seriously endangered. I'm starting to hear futile cries of "The treadmill is not a road!" in my sleep. The whole thing is like a Monty Python skit that has gone on way too long.

I will just note one possible motive for Humber's bizarre notions that I don't think has been mentioned. There is a category in the JREF's Pigasus Awards http://www.randi.org/site/index.php/pigasus-awards.html, added in 2005, which does not appear to have been awarded yet. It is for "Most Persistent Refusal To Face Reality". By god, if Humber hasn't earned this in runaway fashion, there is no justice in the world. I applaud him for an effort that has really set new pinnacles of clue-resistance, and would like to be the first to nominate him to be the inaugural recipient of this esteemed honor.

Tunny
In the Humberverse, of course, this award will go, for the umpteenth year in a row, to "Everyone Else in the World But Humber", for their persistent and unanimous refusal to accede to his view of, well, anything.

 

[Clive]

The whole thing is like a Monty Python skit that has gone on way too long.

Tunny, you can be the seconder for my earlier post... although I sure others will have prior claims on being the first to note humber's almost unbelievable persistence. Come to think of it, Monty Python has probably now been mentioned in this thread more often than agreement with humber on any non-trivial matter has ever been noted (and perhaps even when including the trivial cases)!

 

[spacediver]

In the news today:

Treadmill v. outdoors - the difference is minimal

aka Humber was wrong

http://www.theglobeandmail.com/serv...y16/EmailBNStory/specialScienceandHealth/home

 

[spork]

In the Humberverse, of course, this award will go, for the umpteenth year in a row, to "Everyone Else in the World But Humber", for their persistent and unanimous refusal to accede to his view of, well, anything.

I assure you that if humber was to be given this award he would rejoice and explain to us how it proves his case that the "treadmill is not valid".

 

[Dan O.]

And yet, you have demonstrated repeatedly, for over a month in hundreds of posts, that you do not understand the concept of relative velocities.

I've asked humber several times to answer these simple questions. He hasn't even tried to answer. This is what makes me believe that humber is only a troll. I believe we could ask any fifth grader these questions and get the correct answer (unless perhaps they were home schooled). Humber can't answer these questions because getting the right answers confirms the equivalency of the treadmill situation and getting the wrong answer would place him lower than a 5th grader on the education scale.

In situation A, we have a cart facing West traveling East to West at 10 m/s on the flat surface of a road and the air moving East to West at 10 m/s.

In situation B, we have a cart facing West on the flat surface of a treadmill where the surface is moving West to East at 10 m/s in a room with still air.

For each situation:
What is the speed of the cart relative to the surface?
What is the speed of the air relative to the surface?
What is the speed of the air relative to the cart?

Referencing only the surface, the cart and the air, what difference exists between situation A and situation B?

 

[spork]

I have no intention of funding your ignorance.

So we can only interpret this two ways... humber is either so completely confused that he actually doesn't understand this simple arrangement (that can't cost him a dime if it is us being educated), or he's just smart enough to understand that it would cost him $1000.00 to be told he's wrong.

I could believe either one. But frankly I have a hard time believing he's as thick as he's making out.

 

[Brian-M]

Heard the news? Speed of light is absolute.
An inherent value of differential measurement, is that you need no absolute.

Last I heard, the speed of light changes according to the density of the medium through which it is passing. That doesn't sound "absolute" to me.

Seriously though, the speed of light isn't particularly relevent in a thread that's supposed to be discussing classical/Newtonian physics.

 

[Brian-M]

In real wind, the smoke from a flare placed on the road some distance ahead, will flow with the appropriate velocities for both the driving and boundary flows.
Traveling along that road, towards that flare, would mean that you would run into that smoke sometime in the future. But what happens if both the smoke and cart are exactly at windspeed? The smoke would always be ahead of you, except for the fact the laminar flow is slower, allowing you to gain on it. The relative or apparent speed of that flow when you catch up to it, may be small. It may just drift by.

This is not what happens on the belt. Smoke from the future, would pass by you, at full essentially windspeed, in the opposite direction no matter what. This is partly due to a nest of errors, but also because there is no 'distance' on the belt. Motion is seen as velocity or displacement but the two never meet.

Not true.

Let's simplify things by assuming that the smoke is released by the flare above the boundary layer.

If you were travelling along the road at wind-speed, the only smoke you'd encounter is the smoke released by the flare in the exact moment you passed it. The smoke released before and after you passed the flare would remain the same distance ahead of and behind you as when it was first released.

If you were travelling along a treadmill belt at windspeed (ie. remaining in place relative to someone standing next to the treadmill belt), the only smoke you'd encounter is the smoke released by the flare in the exact moment the flare passed you. The smoke released before and after the flare passed ypu would remain the same distance ahead of and behind you as when it was first released.

From your perspective, the situation is the same as if you were travelling along the road at windspeed.


Now as for the boundary layer, I don't really understand what your diagram is trying to tell me. To help you out, I've made up some diagrams of my own. In these diagrams, a stick man has a little device that tells him the speed of the air, boundary layer and surface relative to him.

On the ones to the left, he's standing on the surface. On the ones to the right, he's travelling at windspeed. The one in the bottom right corner, you can imaging he's standing next to the treadmill belt instead of being in the balloon, if you want. Same thing.

(Click To Enlarge)​

Do you disagree with any of this?

 

[Brian-M]

no. The belts used in real-wind windtunnels are not roads.


It's your money, brian-m.
That may well be true, but no matter what, the belt in that tunnel is not a road. That is 100% of any difference you are likely to suggest.

yes. The relative velocities are the same as (4) but little else. The means by which the wind is generated and delivered to the cart are quite different.
Also, the belt is not a road !


No.
The assumption that a belt is a road, is entirely false. It can never be a road under any circumstances. For all the vehicles that you have ever seen on a belt, the behavior is not like that of a vehicle on the road.
Why? Nature does not allow motion on the spot.

What belt???

Humber, I appreciate your response, but there seems to be a misunderstanding here.

There is no belt in this wind tunnel. The cart is being blown along the floor of the wind tunnel.

In fact, if it makes things easier for you, when the cart it blown to the end of the tunnel a technician picks it up, and puts it back at the start, and the test begins again. If the truck needs to speed-up or slow-down, he waits until the technician picks up the cart, so the acceleration does not affect the results. The performance of the cart is being recorded by video cameras and a speed-camera.

So when the truck is stationary, the cart is on a solid, stationary surface, and the wind is blowing along the wind tunnel, just like the wind blows along a stationary road.

Armed with this information, could you go over the wind-tunnel situation again and tell me where my error are?

As for the boundary layer, let's assume that the floor of the wind tunnel is smooth enough that the boundary layer is negligable.

 

[Brian-M]

One way that might make things clearer would be to explicitly state the profile of the boundary layer for our given wind speed (and assumed identical surface characteristics). For example, a very crude approach would be to simply say the boundary layer is 10 mm deep, and the speed of the air within the boundary layer (relative to the surface) varies linearly from 0 m/s at surface itself up to full wind speed at 10 mm above. Now choose some height above the surface for your boundary layer velocity vector in the diagram, perhaps 7mm. Therefore the speed at that height is 7 m/s relative to the surface. In the treadmill diagram that is 3 m/s to the left relative to the your chosen reference (effectively the ground the treadmill is resting on yet again) because in that case the belt is moving left at 10 m/s.

Shhhh.... If you tell him that the speed of the boundary layer is infinetly graduated between surface-speed and wind-speed it might make his head explode.

But then again, that might not be a bad thing.

 

[Brian-M]

See this is why I prefer to stick to the original french version of 'metre' and 'litre': what you have described is a device for measuring newtons (like a milometer measures miles).

And the sad part is I live in a country where metric units have been standard since long before I was born. But then again, it could be that I sometimes have trouble remembering which way around certain letters are supposed to go. I often write peice instead of piece. Or was it the other way around?

Use only the original.

Good advice, Humbre.

 

[Brian-M]

If that is true, then the velocity is relative to the Sun. That applies to all objects on he planet. Otherwise, I wonder why we would need fuel to move our cars?


I think that our dependency on fossil fuels says that it does come from somewhere. If not who needs a treadmill motor?

I've just thought of an interesting question.

A parked car has no kinetic energy, right?
Two parked cars have no kinetic energy either.

But what if you parked the cars on opposite sides of the planet?

This means they would each be moving at around 1000mph in opposite directions, relative to the average motion of the earth.

But they're also stationary, parked on ordanary streets, with pedestrians walking past them.

Would they have kinetic energy now?

 

[Brian-M]

OK, still not right. Please show him the treadmill video, perhaps #7
If the cart can travel back from the belt to stationary, that is another matter. I expect that he thinks that is the case. As I have said, belts are not roads.

Spork... Since it's your video, can you remind Humber that in video #7 the treadmill is tilted upwards?

 

[Brian-M]

Everything is relative to zero, H'ethetheth !

And we arbitrarily choose to use ground as zero most of the time, simply because it's a very convenient reference point.

Zero is simply the velocity we choose to measure other velocities from. It's our starting point, one whe choose purely for convenience, nothing more.

Most objects around us are travelling at the same velocity as the nearest portion of the earth's surface is, so for convenience we use that velocity as our benchmark, or zero.

Using ground as zero is a convention of convenience, nothing more.

BTW
Your repeated comments on speeding tickets are being ignored for the very good reason that they're obviously intended to refer to velocity relative to the ground. Nobody here believes that you could talk your way out of a speeding ticket by arguing that velocity is relative. The policeman could simply point out that your velocity relative to the road exceeded the speed limit and hand you the ticket.

 

[spork]

Spork... Since it's your video, can you remind Humber that in video #7 the treadmill is tilted upwards?

It is indeed on a positive incline. Unfortunately, this is a rare video where we didn't show a level on the treadmill deck at the beginning of the test. But to make our treadmill level requires putting phone books under the deck at the aft end. So even if it's on the lowest incline, it's still on a positive incline. We also know it has no trouble climbing the treadmill on its steepest setting. I'm happy to shoot a video showing that - if it actually proves anything. No point in doing it if humber is just going to explain how this confirms everything he claims.

 

[Brian-M]

There is a mistake in your interpretation. All KE's appear to all views, except one. Yes, the view from that object itself. Useless, but if you like, true.
In order to make your version stick, the only other objects from which zero KE exists, are other objects in the same "frame". These you must artificially create, so that they become indistinguishable from the other object of that comparison.

Um, no. When any object has zero velocity relative to another, then these objects have zero kinetic energy relative to each other. This applies in all inertial frames of reference, always, regardless to how fast they are moving.

How do you artificially "create" a frame? All possible inertial frames of reference already exist. An inertially frame of reference is just a fixed velocity. To make use of it, you just call it zero and measure all other velocities from it.