**Ask a monkey a physics question thread**

[BananaStand]

Thetans maybe?

[OngBonga]

Steady on with the thetans talk. This is the phsyics thread, not the monkey retard thread.

[OngBonga]

The uncertainty principle says that, even with "perfect" measurement devices, you still cannot simultaneously measure the position and momentum of something to arbitrarily high precision.

hmmm I kinda saw the "uncertainy principle" as the quantum version of the tyre pressure thing, that it was basically impossible to obtain a perfect measurement because to measure velocity perfectly changes the location, and vice versa. Clearly not.

It's a comfortable view, but not falsifiable by any known means, so not, strictly speaking, science.

I thought this theory got revived in the 50's? Is De Broglie–Bohm theory not science in the strictest use of the word?

[Poopadoop]

Why does a spinning object fly straighter than a non-spinning object?

[MadMojoMonkey]

Why does a spinning object fly straighter than a non-spinning object?

Conservation of angular momentum.

In an isolated system, the angular momentum of the system is a constant.

[Poopadoop]

Conservation of angular momentum.

In an isolated system, the angular momentum of the system is a constant.

Uh, yeah.

Now how about in English?

[MadMojoMonkey]

Uh, yeah.

Now how about in English?

Sorry.

***
"In an isolated system,"
I'm talking about a spinning thing (or group of things) that is not being torqued or pushed by anything

"the angular momentum of the system"
The total amount of spinning-ness of the thing

"remains constant"
does not change.

***
For clarity of nomenclature, spinning things don't fly straighter than non-spinning things, they maintain stability while flying just as straight as an unstable thing.
(or I've misunderstood your question.)

It's the rotational equivalent to Netwon's First Law
"In an inertial reference frame, an object in motion will remain in motion at a constant velocity if and only if the vector sum of forces acting on the object is 0 N."
(Note that 0 is a 0 vector, for the math nerds who care about that stuff.)

In other words:
Stuff changes how it moves only when it's pushed, but pushes which cancel each other out don't change how objects move.
Therefore, we can deduce if something has been pushed by seeing if it changes how it's moving. If it changes, it was pushed.

A nearly identical rule holds for spinning things. If they change, then they must have been pushed. If nothing is pushing (or all pushes are cancelling out), then it will not change.

Spinning things have a non-0 rate of angular momentum (actively spinning inertial mass). Since it is spinning, it will not change without a push... but now I have to clarify that a spinning push is a torque. So spinning things only change their spinning if they are torqued.

Spinning things have an axis of rotation, which partly defines their spinning. If the orientation of that axis of rotation changes, that requires a torque to have changed it. In general, the friction on a spinning object is such that it slows the spinning w/o changing the orientation of the spinning axis.

So, like, a frisby maintains stability because it is spinning and that spinning has an axis of rotation. In order to change the axis of rotation, a torque must be applied to the frisby. However, the air resistance acting on the frisby supplying a torque is generally pretty balanced around the edge of the frisby, putting roughly equal forces of friction all around the frisby. These tend to slow the rotation w/o changing the orientation of the rotation.

It occurs to me that a frisby always rolls over to one side and that since it is moving forward as it spins, the air velocity across the advancing edge of the frisby will not be the same as the friction along the retreating edge. This could cause a net torque which serves to drive the roll-over of the frisby.

[OngBonga]

Uh, yeah.

Now how about in English?

I'll give it a bash.

Take the earth-moon system, and simplify it to say that the moon is moving perpendicular to earth, while earth's gravity acts to draw the moon towards earth. If the moon was not moving perpendicular to earth, it would fall directly towards earth. But because it has linear velocity, then it moves in a circle around earth (I emphasise, very simplified).

That's conservation of energy.

Conservation of angular momentum is basically the same, only applied to a rotating frame of reference. If you imagine a spinning top, if you give it a push to try and make it fall over, it won't, because the part you made fall towards the direction of gravity has moved and is now going against gravity, before reacing its apex and going back down with gravity, etc.

Conservation of angular momentum is basically conservation of energy, just more complex because of the nature of motion.

[MadMojoMonkey]

I thought this theory got revived in the 50's? Is De Broglie–Bohm theory not science in the strictest use of the word?

If you can find a way to measure the pilot wave and show that it is a physical thing, and that particles follow deterministic trajectories, in compliance with the forces of the pilot wave, then Nobel Prize for you, sir.

Note: I am not authorized to hand out Nobel Prizes.

[MadMojoMonkey]

hmmm I kinda saw the "uncertainy principle" as the quantum version of the tyre pressure thing, that it was basically impossible to obtain a perfect measurement because to measure velocity perfectly changes the location, and vice versa. Clearly not.



I thought this theory got revived in the 50's? Is De Broglie–Bohm theory not science in the strictest use of the word?

All known attempts to make a comfortable, intuitive, sensible explanation of QM have either been terribly flawed in inconsistencies or have failed at their goal.
The 3 most popular interpretations are as follows:

As we've discussed briefly, the pilot wave hypothesis relies on these imaginary forces that make deterministic processes appear random.

The many worlds interpretation cannot be falsified, either. That's the idea that all possible quantum states exist simultaneously, and our universe represents one particular probability slice of that poly-verse.
(Any Hitchhiker's Guide fans, here? The "Whole Sort of General Mish Mash" bit always comes to mind when I think of the many worlds theory.)
Anyway, since we can only observe our own universe, by definition... our universe is everything we can observe and all that is directly implied we could observe if we had been in the right place at the right time. There is no way to measure these other universes' outcomes.

I tend to preach the Copenhagen interpretation like it's gospel, but it's equally messed up in the assertions. A few posts back, I explained Young's double-slit experiment as the evolution of a wave which exists in a superposition of states, and even when a particle doesn't get detected by a detector, the wave function still interacted and collapsed, leaving the rest of the wave function to continue.
So I asserted that a lack of detection (or any measurable event, for that matter) still caused a measurable change in the universe - the pattern on the wall behind the undetected hole still looks like the pattern behind the detected hole, so long as the detector is on.

That assertion relies on unmeasurable events being causes, in much the same way that I criticize the pilot wave interpretation.
:/
Frankly, I should look at the pilot wave interpretation a bit more closely. I like Copenhagen because it relies on the math, which is experimentally confirmed. On the surface, that's also true of pilot wave, so ... cool.

[OngBonga]

If you can find a way to measure the pilot wave and show that it is a physical thing, and that particles follow deterministic trajectories, in compliance with the forces of the pilot wave, then Nobel Prize for you, sir.

I'm on it.

[CoccoBill]

I think poop is asking why guns have rifling.

[Poopadoop]

That, or why you spin a ball when you throw it.

A spinning object doesn't fly straighter than a non-spinning object? Then what is the point of making it spin - what is rifling for, for instance?

I thought if the thing wasn't spinning, it was free to rotate in all kinds of weird ways (e.g., a bullet flying end-over-end) which could cause the wind resistance to make it deviate from a straight path. I just didn't understand how the spin kept it straight.

Isn't the whole idea of a knuckleball to remove the spin from the ball so it will move in unpredictable ways?


So ya, my question is why does imparting a spin to an object keep it from tumbling around in the air?

[MadMojoMonkey]

A spinning object doesn't fly straighter than a non-spinning object? Then what is the point of making it spin - what is rifling for, for instance?

I thought if the thing wasn't spinning, it was free to rotate in all kinds of weird ways (e.g., a bullet flying end-over-end) which could cause the wind resistance to make it deviate from a straight path. I just didn't understand how the spin kept it straight.

Sorry if I've been confusing. This is exactly what I mean.
(You've also touched on the answer to your question. more in a bit)

In an inertial reference frame, accelerations are caused by forces, not by spinning.

The spinning doesn't make it fly straight, it makes it less susceptible to tumbling.
This makes is less effected by the forces of wind resistance.
The reduced effect of wind resistance makes it fly straight by reducing random accelerations from causing it to deviate from its trajectory.

Take away the air, and the air resistance which exerts forces on those objects goes away, and the spinning doesn't matter.
Things fly straight, spinning or not.
(Well, in a gravitational field, they follow trajectories, which are not "straight" outside of invoking GR.)

That, or why you spin a ball when you throw it.
[...]
Isn't the whole idea of a knuckleball to remove the spin from the ball so it will move in unpredictable ways?

So ya, my question is why does imparting a spin to an object keep it from tumbling around in the air?

Yes.

Imparting a spin means that any "small" torques which are exerted by wind resistance will have a less dramatic effect on the direction the thing is rotating. Since it's spinning "really fast" about an axis, any "small" torques which are exerted on it will "probably" not change its direction of rotation "very much." Just like if something is moving "really fast" in a straight line, any "small" random forces will cause it to deviate, but it's "probably" still "generally" moving in the same direction it was.

[OngBonga]

(Well, in a gravitational field, they follow trajectories, which are not "straight" outside of invoking GR.)

Fuck you, invoke GR. It's a straight line.

[MadMojoMonkey]

Fuck you, invoke GR. It's a straight line.

I was thinking of you when I typed that.

While technically you are correct, it doesn't make this explanation any simpler.

[OngBonga]

The many worlds interpretation cannot be falsified, either.

I still haven't thrown a cup of boiling tea in my face.

That assertion relies on unmeasurable events being causes, in much the same way that I criticize the pilot wave interpretation.

From what I could tell, there wasn't much between Copenhagen and pilot wave. The difference seems to me that one is an outcome determined by probability, while the other is an outcome determined by initial conditions. The latter seems much more intuitive to me.

I really, really do not like the idea that everything we observe is a roll of the dice. I don't like randomness in nature. It don't believe randomness exists in nature, just apparent randomness that needs better understanding. But this opinion is much more philosophical than scientific. This is why I like pilot wave (or whatever it evolved into), it removes that aspect from QM. That's not to say I understand pilot wave, because I don't, but I like it.

[OngBonga]

It's important that the water is evaporated by energy taken from the room. Adding an energy source to evaporate the water kinda eliminates the point.

The water would be evaporated by the excess heat in the room. The question would be how to remove the water from the air without putting heat back into the room. A dehumidifier will condense water, so that releases the energy back into the room. I suppose I could vent the air out of the room onto the landing, where I can run the dehumidifier. That takes the heat into another room, which has better ventilation.

[OngBonga]

I had a suggestion from a friend... put a plant next to the computer. Evapotranspiration will cool the immediate surroundings, and if I can keep on top of humidity, then this process will be maximised. This might be more pleasing to the eye than having trays of water lying around.

[MadMojoMonkey]

What about making a heat exchanger?

Set up a freezer in the landing. (or wherever, so long as it's radiator is outside the room).
Wind some copper tubing into a coil and make sure a fan is blowing across the coil.
Attach a flexible, insulated tubing like surgical tubing to the ends of the coil and run those ends out of the room.
Attach another bit of copper tubing to the ends of the flexible tubing and set that in the freezer
Add some water & anti-freeze to the tubing as your working fluid.

A pump may or may not be necessary. If the coil and fan in the room is lower in elevation than the freezer, convection will drive a flow. Probably convection wont be enough, so a pump is likely to be necessary.

The freezer can be replaced with a cooler full of ice, but the freezer requires less maintenance.

[OngBonga]

Hmm interesting. I'll try plants first, I like that idea because it's easy maintenance plus it looks nice, also minimal setting up. If that doesn't help matters, I'll look at this little setup. Sounds like it could be fun. Cheers.

[Poopadoop]

Hmm interesting. I'll try plants first, I like that idea because it's easy maintenance plus it looks nice, also minimal setting up. If that doesn't help matters, I'll look at this little setup. Sounds like it could be fun. Cheers.

Why don't you just buy a bag of ice (or make some in the freezer), put it between you and a fan, and blow the fan over the ice?

[OngBonga]

Why don't you just buy a bag of ice (or make some in the freezer), put it between you and a fan, and blow the fan over the ice?

Problem is that I'd need to keep doing it. How long does a bag of ice last in a room that's 35 degrees?

Ong are you mad, just buy a water cooling system for your pc, they aren't exactly expensive and they'll actually work as opposed to a plant.

My PC is probably worth a fiver, so not sure if worth it. Still, I'll look into this, certainly when I replace this heap of shit.

Plants should work. Evapotranspiration is a thing that plants do, and it cools air around the plant.

Do they not have air conditioners in the UK?

They're not cheap, and for the most part, we don't need them. We probably have a max of 5 days a year where it's +30 degrees outside.

[Savy]

Ong are you mad, just buy a water cooling system for your pc, they aren't exactly expensive and they'll actually work as opposed to a plant.

[BananaStand]

Do they not have air conditioners in the UK?

[Savy]

Do they not have air conditioners in the UK?

Not in homes, why would we need it?

[BananaStand]

Not in homes, why would we need it?

To condition air

[Savy]

To condition air

Clearly you've never been to the UK.

[BananaStand]

Clearly you've never been to the UK.

Clearly.

And I don't see it as a bad thing either. It doesn't seem like a nice place. Every time I see pictures, it's raining. Everyone's teeth are fucked up. Your government has elections whenever it wants. And I have to say, a woman with a british accent is probably the least sexy thing on earth. It's a tragedy when the woman is actually attractive. It's like being served your favorite meal, but then the waiter spray-farts on it.

Anyway......none of that explains why you don't have air conditioners. You have windows, you have electricity. All you need now is 90 bucks to buy the AC unit and it's your world.

[MadMojoMonkey]

Keep it on topic, lads. This is the physics thread.

[BananaStand]

Keep it on topic, lads. This is the physics thread.

Ok, please confirm my understanding of physics here.

You feel hot because it's summer time. You go to the store, pick out an AC unit, give the guy at the register 90 bucks, and then go home. You put the unit in your window, close the window on top of it, and plug it in. Then you hit the switch and you live in climate controlled bliss until winter.

Is that how it works?

Now, what kinda silly physical anomalies are preventing that same thing from happening in jolly ol' england?

[OngBonga]

Now, what kinda silly physical anomalies are preventing that same thing from happening in jolly ol' england?

Something called cost/benefit ratio. It's not just 90 bucks, you've also got to run the thing, which costs x amount on your monthly outgoings. Furthermore, when it's being used 5 days a year, one has to question if it's just better to suck it up on the few hot days we have.

[BananaStand]

Something called cost/benefit ratio. It's not just 90 bucks, you've also got to run the thing, which costs x amount on your monthly outgoings.

Great, now weight that against the cost of getting a new computer. Or consider the cost to your relationships when your friends come over and see you running a fan over trays of ice so you can maintain the toy you use for internet rants and porn.

90 bucks seems like a steal.

[OngBonga]

I'm sure I said somewhere that my comp room has no windows. Where the AC unit going?

Great, now weight that against the cost of getting a new computer.

That's gonna happen this year anyway.

Or consider the cost to your relationships when your friends come over and see you running a fan over trays of ice so you can maintain the toy you use for internet rants and porn.

I'm going with houseplants first, remember? I don't think my friends will find anything unusual about that. Even so, I'm not in any hurry to invite guests into my warm humid comp room with one seat so we can watch porn together.

[Keith]

I'm sure I said somewhere that my comp room has no windows. Where the AC unit going?



That's gonna happen this year anyway.



I'm going with houseplants first, remember? I don't think my friends will find anything unusual about that. Even so, I'm not in any hurry to invite guests into my warm humid comp room with one seat so we can watch porn together.

I'm guessing the sale of the "houseplants"grown in the warm humid room with no windows will be financing the new computer

[OngBonga]

Anyway, let's take this convo to another thread.

[OngBonga]

Back to physics...

http://www.bbc.co.uk/news/science-environment-39642992

What the actual fuck is negative mass? I've come to understand mass as resistance to acceleration. The "heavier" something is, the more resistance it has. Something with zero mass, ie a photon, has no mass because it has no resistance to acceleration... it always moves at c, so does not experience a change in state of motion, thus, no mass.

So how can negative mass be explained in inertial terms?

[BananaStand]

Back to physics...

http://www.bbc.co.uk/news/science-environment-39642992

Am I understanding this correction if I'm envisioning this discovery leading to the development of tractor beams?

[OngBonga]

Am I understanding this correction if I'm envisioning this discovery leading to the development of tractor beams?

I'm not understanding it at all right now. I'm hoping mojo can explain this in inertial terms so I can get my head around it.

[BananaStand]

I'm not understanding it at all right now. I'm hoping mojo can explain this in inertial terms so I can get my head around it.

I'm kind of focusing in on the part where if you push an atom, it moves toward you. And I'm envisioning US satellites firing something at North Korean missiles that makes them fly upwards and off into space.

[OngBonga]

I'm kind of focusing in on the part where if you push an atom, it moves toward you. And I'm envisioning US satellites firing something at North Korean missiles that makes them fly upwards and off into space.

Obviously this is speculation because I have no fucking idea what we're even talking about, but I'm assuming that the amount of force required to propel something is the same... just in the opposite direction. So I'm not sure it has potential applications when it comes to propulsion.

For argument's sake, let's say it takes 100 of energy to propel something into orbit, with the force applied underneath the object. Well, we still need 100 energy, we just apply the force to the top instead.

However, the term "fuck knows" keeps popping into my head.

[MadMojoMonkey]

Back to physics...

http://www.bbc.co.uk/news/science-environment-39642992

What the actual fuck is negative mass? I've come to understand mass as resistance to acceleration. The "heavier" something is, the more resistance it has. Something with zero mass, ie a photon, has no mass because it has no resistance to acceleration... it always moves at c, so does not experience a change in state of motion, thus, no mass.

So how can negative mass be explained in inertial terms?

lol
"not the apparatus used in the latest research"
Editor was all, "I don't care. Put a sciency picture on this article, dammit!"

***
They're saying that it's the inertial mass that is negative (no mention of gravitational mass). They're not saying any known laws of physics need revision.
So F = ma, still. (bold letters used to indicate vectors)
F doesn't change, a doesn't change, only the sign of m changes. The result is that the applied force causes acceleration in the opposite direction of the force.
Meaning that if I push something with negative mass, it will move toward me, not away from me, as expected.

They're not saying any single particle behaves this way. They're saying there is a region of the Bose-Einstion Condensate which behaves in this way.
It sounds like it's a property of the system, and not of the particles.

This still needs peer review and replication as far as I can tell.

[OngBonga]

They're saying there is a region of the Bose-Einstion Condensate which behaves in this way.

Hmm ok well my very limited knowledge of this stuff is that it flows without losing energy, so I guess there's certainly going to be unusual currents.

I'll wait for that peer review before wasting valuable stonedness on this matter.

[OngBonga]

They're saying that it's the inertial mass that is negative (no mention of gravitational mass).

Well they're the same so if one is negative so is the other. Isn't it intuitive why they're the same? Inertial mass is resistance to acceleration... force acceleration mass thingy... well that what's happening in a gravity field... gravity provides the force, the ground causes acceleration in the form of constant change of velocity (constantly stopping you falling at terminal velocity), so gravitational mass is the resistance that stuff has to this acceleration. How has this not been resolved like 70 odd years ago? Why is something that causes brilliant people headaches so obvious to me? Is my weed really that good or am I missing something?

[MadMojoMonkey]

The theories we use to describe these forces are dramatically different, though.

All other forces are understood as the exchange of quantum particles.

Gravity is understood as curvature of spacetime.

There is no a priori reason things with disparate explanations should have similar effects.

I don't know anyone who doesn't agree with you that it seems obvious, but the logical ideas (math) uniting QM and GR are as of yet still unknown.

[OngBonga]

All other forces are understood as the exchange of quantum particles.

Oh ok, I see where the problem is. Ok, this quoted bit is probably wrong. The other forces are also curved spacetime, just much more profound, and much more localised.

Solved.

[OngBonga]

haha I wish. If it were financing anything, it'd be an AC unit first and foremost.

Be suspicious when I pretend I've got a job.

[a500lbgorilla]

Just for fun, how do rockets fly?

like this:

http://i.imgur.com/6qhtZa1.gifv

[MadMojoMonkey]

Nice

[CoccoBill]

MMM, if you could get the answer to one scientific question, free of charge, what would that be?

Oh and thanks for your answer to my previous Q, I'm still digesting it. Great stuff.

[BananaStand]

MMM, if you could get the answer to one scientific question, free of charge, what would that be?

I'll bet it's black-hole related

[MadMojoMonkey]

MMM, if you could get the answer to one scientific question, free of charge, what would that be?

I'm guessing you mean something like, "What, in my opinion, would be the most revealing question in physics to know the answer to?"

What is the theoretical link between QM and GR?

***
There's a wiki page on unresolved problems in physics. It's not a short page.

Oh and thanks for your answer to my previous Q, I'm still digesting it. Great stuff.

I'll bet it's black-hole related

Yep.

[Savy]

I'm guessing you mean something like, "What, in my opinion, would be the most revealing question in physics to know the answer to?"

What is the theoretical link between QM and GR?

You'd choose that over fusion?

[MadMojoMonkey]

You'd choose that over fusion?

What about fusion?

What specific question do you think I'm missing?

[CoccoBill]

What is the theoretical link between QM and GR?

Ok, yeah I guess a unified theory would be a big one. I'd have started with either "what causes gravity" or "what caused the big bang" or something. I'd assume we'd get a better idea of those too with a unified theory.

[MadMojoMonkey]

Ok, yeah I guess a unified theory would be a big one. I'd have started with either "what causes gravity" or "what caused the big bang" or something. I'd assume we'd get a better idea of those too with a unified theory.

I'm not sure if these are science questions.

Science can only describe and predict "what" happens. It has nothing to say on the matter of "why" anything happens.

[MadMojoMonkey]

Whaaaaaaaaaaat...?

What is this "time crystal" thing you made?

http://www.livescience.com/58171-tim...n-the-lab.html

I'm just gonna put a pre-emptive set of:
IDK
IDK
IDK
IDK

for your coming questions.

(I may be able to answer some stuff, but the specifics are lost on me.)

[OngBonga]

There's a wiki page on unresolved problems in physics. It's not a short page.

I'm on it. Might take an hour or two.

[OngBonga]

what causes gravity

He can just ask me that, and then correct me when I get it slightly wrong.

[OngBonga]

It's cold fusion that's slightly problematic.

And by slightly you mean extremely?

[OngBonga]

If I could have the answer to a phsyics question, it's how can I turn dust into weed.

[MadMojoMonkey]

@ong: No. Skin is not rich in either magnesium or calcium. That's what fertilizer is for.

@poop: I concede that neither of us is definitively correct on the question of "what is dust?"

A) There are a ton of conflicting sources, and even the quotes I can find by "experts" on dust lack any links to their studies and data.

B) Dust is a definition of particulate size. Any object or substance which is of that physical size is considered dust.
Therefore, the composition of dust varies widely from location to location.
(Dust at a smelter is going to be dramatically different than dust in a house.)

C) Dust from textiles and hair tends to be fluffy, or lower density than skin dust. Dust from human skin cells and the dust mites that eat them tend to be compact, and have a higher density.
The ratio of what is most prevalent will be different if you're comparing amounts by volume or amounts by mass.
The sources I've found do not state which metric they've used to draw their conclusions.

[Poopadoop]

@poop: I concede that neither of us is definitively correct on the question of "what is dust?"

Don't concede anything on my behalf lol.

A) There are a ton of conflicting sources, and even the quotes I can find by "experts" on dust lack any links to their studies and data.

B) Dust is a definition of particulate size. Any object or substance which is of that physical size is considered dust.
Therefore, the composition of dust varies widely from location to location.
(Dust at a smelter is going to be dramatically different than dust in a house.)

C) Dust from textiles and hair tends to be fluffy, or lower density than skin dust. Dust from human skin cells and the dust mites that eat them tend to be compact, and have a higher density.
The ratio of what is most prevalent will be different if you're comparing amounts by volume or amounts by mass.
The sources I've found do not state which metric they've used to draw their conclusions.

One thing that seems clear is that there isn't sufficient volume or mass of shed skin cells to make up the majority of house dust. An empty house collects dust, for example, though there's obviously no human skin cells being shed in it. I'm inclined to think house dust is mostly mineral matter (i.e., dirt) and plant matter (e.g., pollen), with animal matter coming in a distant third behind those two.

[MadMojoMonkey]

Don't concede anything on my behalf lol.

That's fair.
I didn't mean to.

Oops.

One thing that seems clear is that there isn't sufficient volume or mass of shed skin cells to make up the majority of house dust.

Upon what data is this assertion based? I looked for any data to affirm or refute this claim and I found none.

An empty house collects dust, for example, though there's obviously no human skin cells being shed in it.

This is already addressed by my point (B) above.

I'm inclined to think house dust is mostly mineral matter (i.e., dirt) and plant matter (e.g., pollen), with animal matter coming in a distant third behind those two.

If you're not willing or able to present data on this, then you're welcome to start the "Things Poopadoop is inclined to think, despite the dearth of evidence" thread.

[Poopadoop]

If you're not willing or able to present data on this, then you're welcome to start the "Things Poopadoop is inclined to think, despite the dearth of evidence" thread.

How about "Things that appear to be common sense" thread?

Your outer layer of skin regenerates once every 35 days. Take that amount of dead skin cells, multiply it by the number of people in the house, subtract a big chunk for the skin that gets sloughed off while people are outside the house and/or washed down the shower/sink drain, then divide that by the surface area of everything in the house, including carpets, tables, etc.. How thick a layer of dust do you think that would make?

Maybe you should start a "Things you heard somewhere and thought sounded cool so you repeated them as though they were facts, and then got argumentative when someone pointed out they were bullshit" thread.

[MadMojoMonkey]

How about "Things that appear to be common sense" thread?

That'd be fine, too.

Your outer layer of skin regenerates once every 35 days. Take that amount of dead skin cells, multiply it by the number of people in the house, subtract a big chunk for the skin that gets sloughed off while people are outside the house and/or washed down the shower/sink drain, then divide that by the surface area of everything in the house, including carpets, tables, etc.. How thick a layer of dust do you think that would make?

I'm not saying you're wrong. I'm saying I can't find any data which backs up your claim.
I'm saying if you can't or don't want to find any data which supports your position, either, then this is the wrong thread.

Maybe you should start a "Things you heard somewhere and thought sounded cool so you repeated them as though they were facts, and then got argumentative when someone pointed out they were bullshit" thread.

I didn't say it because it sounds cool. I said it because my best friend for 30 years wrote a paper on dust (admittedly, in high school), and he told me the thing about skin cells. It seemed like a reliable enough source at the time. It wasn't until you questioned it that I ever heard contrary.

I took your position to heart and embraced skepticism about my own position. I looked for relevant data or evidence to elucidate the situation. I found inconclusive statements from "experts" and contradictory statements between different articles.

I'm not arguing with you. I'm saying I can't find evidence to definitively support either of our positions.
If anything, I'm disagreeing with your position as definitive, and I've stated 3 reasons for my skepticism.

[OngBonga]

@ong: No. Skin is not rich in either magnesium or calcium. That's what fertilizer is for.

I think if I'm gonna plant a seed, I'll find a better medium than fertilised dead skin cells.

[MadMojoMonkey]

A hypothesis!

Now test it, and share your results!

***
I don't get why you're so feisty on this issue.

Clearly, dust accumulates where people are not... as dust is a measure of particulate size, nothing to do with humans.
We're not talking about dust in random non-occupied places, though. We're talking about homes in use by people.

All I'm saying is that it's plausible to me that in some houses there are significant human skin cells, dust mites, and mite excrement in the dust to account for a majority of the mass of dust.

Your assertion that this is never the case is strongly worded and requires a strong demonstration of fact to change my mind.

If your sense is so common, it should be easy to conclusively demonstrate your assertion.

[BananaStand]

Your assertion that this is never the case is strongly worded and requires a strong demonstration of fact to change my mind.

Dude...he showed you the math.

Plus he severely lowballed the average house size at 100 m2.

[Poopadoop]

If your sense is so common,

Not as common as I thought, apparently.

it should be easy to conclusively demonstrate your assertion.

It was, did you not read it?

[MadMojoMonkey]

Not as common as I thought, apparently.

This is the reason we need science to root out what "seems" legit from what "is" legit.

"Armchair philosophy" is fine for moral and ethical discussions, but it fails when it comes to making measurable predictions about the world.

It was, did you not read it?

Your statement of plausibility is fine, but it is not a proof, no matter how "reasonable" it sounds.

My critiques:
You've approximated the amount of some human skin dust which you expect in some situations, not all dust in all situations.
You've ignored the amount of dust which is mites and the mites' excrement.
You have not compared those amounts of dust to amounts of dust from other sources.
You have not demonstrated the comparative mass of these sources, as your analysis is based on surface area.
You have not made it clear whether or not you include elements like hair and other macroscopic particles which are commonly mixed in with the household dust, and which I would be hard pressed in a less formal discussion to disagree that stuff is dust.

In short, you've made an argument that human skin is not all of the dust, but you haven't given any context over how much of the dust it is.
Your calculations seem reasonable, but need to now be buoyed by data to support your assumptions.

[Poopadoop]

"Armchair philosophy" is fine for moral and ethical discussions, but it fails when it comes to making measurable predictions about the world.

Agreed. That's why I did the math just to show how absurd it was.

Your calculations seem reasonable, but need to now be buoyed by data to support your assumptions.

I'll get right on that. First I gotta find me a giant ruler to get some hard data on the distance to the sun.

[OngBonga]

I'll get right on that. First I gotta find me a giant ruler to get some hard data on the distance to the sun.

Assuming you could even create a big enough ruler (you can't), a ruler is going to be a really poor method of accurately measuring such large distances. For a start, you'd need to ensure it is perfectly perpendicular to the earth, and that there is no flexing. Also, you're going to have to find a material that is capable of withstanding what I would imagine are immense pressures at the earth end, and definitely at the sun's end. Also, it needs to not expand as temperature increases. Furthermore, you need to accurately measure it and mark it before you can use it. Factor in the time it takes to make the measurement, coupled with the distance between the earth and the sun constantly changing, and I'd say the time you should waste thinking about making a giant ruler should be equal to the time I've wasted making this post.

[MadMojoMonkey]

Agreed. That's why I did the math just to show how absurd it was.

If that's why you did the math, you missed the mark for the reasons which I offered in my critique above.

I thought you were a real-life, published scientist?
What publication would post your above "proof" as science?

I'll get right on that. First I gotta find me a giant ruler to get some hard data on the distance to the sun.

There are plenty of credible sources which contain that datum, but I firmly embrace your DIY spirit of attempting to affirm or refute it with your own experiments.

Keep us posted on your 93 million-mile-long ruler project. I'm quite interested in the engineering challenges you have to overcome to maintain rigidity over such length scales.

[Savy]

What about a really tall and fat person in a really small room? Does it help if they have certain skin conditions?

I need to see some formulas, repeatable experiments, etc.