Banned from Skeptiko until 15 Feb

That whole pendulum discussion arose initially as an attempt to 'explain' a claimed 'anomaly'. However,  no-one actually demonstrated that there was anything anomalous which actually needed to be explained. In fact the pendulum is gradually reducing the size of each swing, just as expected. There is no anomaly, only faulty observation at the outset.

One might add, there is also a naive, childlike trust in accepting the initial claim at face value. Did anyone think it worth checking for themselves?

The difficulty here, and I hesitate to open this can of worms, is that the appeal to settled science only gets us so far... pendulum or otherwise.

We can ask (the consensus of (TCO)) physicists about the model of pendulum action, we can ask (TCO) climatologists about models of climate change, we can ask (TCO) evolutionary biologists about models of evolution. At some point it’s ok to throw shade at ‘science’ (and all mainstream sources) in general to dismiss what we don’t want to hear. Admittedly, that point varies from person to person.

The difficulty here, and I hesitate to open this can of worms, is that the appeal to settled science only gets us so far... pendulum or otherwise.

I certainly was not appealing to 'settled science'.

In this case my point is that we should not simply accept someone else's assertions at face value. It is inappropriate to merely accept unsubstantiated assertions where these are simple enough to re-check for ourselves.

I might add that there have been several other such assertions made in that thread. A little research and fact-checking is worth a mountain of debate about nonsense.

So, do you accept that LoneShaman was fundamentally mistaken on the other two?

No - I simply picked the easiest one to analyse.

I think you mean three dimensions, not two. Yes, it is possible that given a pendulum swinging (especially erratically) in three dimensions, the accelerative and decelerative aspects of the vent's force as applied to the pendulum would not be equal, leading to some overall effect on the pendulum's motion, and tending to keep it swinging, especially in erratic motion. But in any case that scenario does not apply: the bag in question was swinging straight back-and-forth in two dimensions, not (erratically or otherwise) in three.

Given a swing in only two dimensions, I can't think of a way of angling or placing a vent such that the draft does not apply the same force during some part of the bag's upswing as during the equivalent part of its downswing, thus cancelling out its effects - even if that force only acted on part of the pendulum's swing. So, no, I don't think that your argument can be maintained in this scenario.

I said two dimensions because a pendulum can swing in two orthogonal directions - it is just a semantic question.

Clearly if you had a charged pendulum swinging in a plane ine a uniform electric field a uniform force would be applied to the pendulum and that would just shift the point at which it would come to rest, and the motion would just decay exponentially. I think that is what you were saying. One way to look at that is that no energy could be extracted from the charge and the electric field, because neither is changing, and you need energy to cancel the frictional forces. That argument does not apply to extracting energy from a moving gas - otherwise windmills would not work!

However to assume that a postulated air vent would apply a totally uniform force, and that whatever was swinging (tool bag?) was totally fixed to swing in a plane is probably silly. I know that in practice if you suspended a pendulum in front of an active air vent, it would swing at least a bit.

I think as I said above, that over analysing the LEM videos is probably unwise - they were not set up as a physics experiments.

I don't think you can pick a sufficiently clear argument with LS to launch accusations that he is scientifically illiterate, which is why you remain banned.

I really don't want the moon landings to have been faked - those guys were my heros in my late teens and early manhood. I thought of them as super brave explorers, who were engaged in a project whose primary objective was non-military. Even so, some of what LS has posted does have me a bit worried.

David

[Laird]

Clearly if you had a charged pendulum swinging in a plane ine a uniform electric field a uniform force would be applied to the pendulum and that would just shift the point at which it would come to rest, and the motion would just decay exponentially. I think that is what you were saying.

Something like that, yes, although I am not sure that the decay would be exponential - I simply haven't studied that question.

However to assume that a postulated air vent would apply a totally uniform force, and that whatever was swinging (tool bag?) was totally fixed to swing in a plane is probably silly. I know that in practice if you suspended a pendulum in front of an active air vent, it would swing at least a bit.

But David, that the pendulum might "swing at least a bit" if suspended in front of an active air vent is beside the point, because it is far from what LoneShaman actually claimed (via the video he endorsed): he claimed that the pendulum was in a state of perfect perpetual motion with the amplitude of its swing not changing a bit because of the force from an air vent. This is obviously wrong. Don't play games here. You know as well as the rest of us that it's nonsense.

I don't think you can pick a sufficiently clear argument with LS to launch accusations that he is scientifically illiterate

Bullshit. All three misapprehensions of LoneShaman's that I posted are clear and obvious errors. You just want to back your boy because he takes the same position as you on climate change, and you don't like seeing that challenged in strong terms.

which is why you remain banned.

Which is why it remains the case that you are a biased moderator who takes action based on who supports your views, rather than on who genuinely behaves objectionably.

I don't think you can pick a sufficiently clear argument with LS to launch accusations that he is scientifically illiterate, which is why you remain banned.

Surely the simple point is that LoneShaman said that the continued swinging of the pendulum was an indication of an atmosphere. Whereas in fact a pendulum will continue to swing in a vacuum, until it's stopped by friction at the point of suspension. And it will continue to swing for longer in a vacuum than it would in still air.

I don't like banning people,

Surely the simple point is that LoneShaman said that the continued swinging of the pendulum was an indication of an atmosphere. Whereas in fact a pendulum will continue to swing in a vacuum, until it's stopped by friction at the point of suspension. And it will continue to swing for longer in a vacuum than it would in still air.

Well there was talk about an air vent - the discussion went rambling on. Honestly, I don't think there was anything like the evidence that LS is scientifically illiterate. The problem is that none of these scenarios are precisely specified.

If you saw a sign swinging, you would take that to mean there was a  wind. Likewise if  you saw a piece of paper rustling in a room you would suspect a draught of some sort.

David

If you saw a sign swinging, you would take that to mean there was a  wind.

The whole point of that discussion was that - apart from the effect of friction at the point of suspension, which may be very small - a pendulum in a vacuum doesn't need a force to be acting on it for it to continue to swing. That was what LoneShaman wouldn't accept. It doesn't sound as though you accept it either.

The bag was swinging because one of the astronauts had just hung it there, thus giving it some initial momentum. The nonsense about wind is just hot air.