Explanations for this please!

[UKBoy1977]

OK I was talking to my Mum just now about the old 'Levitation party trick' where 4 people lift a person up high using their fingers. You know the one.

Anyway I told her how it is just a case of the weight being distributed over 4 people and them being in a position which gives them good leverage (as explained in Flim Flam!) but she's not buying it. Reason is as follows, and my science is not good enough to argue my case:

She says that the person she liftes was about 12 stone and that she doesn't believe she could lift 3 stone with just her fingers. She performed a variation of it where, instead of just reciting some chant, the 4 people actually pushed down on the persons head and shoulders beforehand. Due to Newton's 3rd law the body of course exerts a reaction force. But she believes the body continues to exert this force after the people have stopped pushing, and this is what made the person feel 'as light as a feather, not 3 stone'

Another example of this effect (she claims) is when you stand in a doorway and push against one side with your arm for about a minute. When you stand away your arm magically rises! Now I admit this is a very cool trick, but I asserted that it was to do with the brain being fooled and continuing to stimulate the shoulder muscle to raise the arm, not that the force she was exerting somehow lingering on even after she had stopped consciously pushing.

Anyway can someone provide a good scientific explanation of the 2 things I have mentioned here as I am running out of ideas! It is particularly hard to explain why the person she 'levitated' feeling literally weightless rather than 3 stones worth. I could just say it was in your head, you were psyched up and didn't really notice the weight, but of course a believer isn't going to accept that!

[UKBoy1977]

Just thought I should add, I just went to check with my Mum that the person she lifted was definitely 12 stone.

"Well it was a 17 year old girl, she was probably 9 or 10 stone, I dunno!"

Hmm. Already things start to become clearer!

(Oh yeah, just in case any US folk here don't know what a stone is, 1 stone = 14 pounds. Sorry if this is patronising anyone, but I do encounter a lot of people on other boards who don't know!)

[zer0vector]

Despite what people think, the strength in one of their fingers (espcially the pointer finger) is pretty close to that of the entire hand. Also, they probably didn't levitate the person very long, so endurance wouldn't be an issue. A good way to test this would be to get a 3 stone weight and actually have her try to lift it.

[Ed]

A quick answer to the second one. Muscles are paired and work in opposition (thats how you can strighten out your arm after you flex it). The opposing muscle is always stimulated when a given muscle is "active". So, when you push on a door and stop, the muscle doing the pushing was depleted of the transmitter that caused it to contract so when the other muscle compensates, it in turn is not being compensated for adequitely by the first muscle so your arm rises. Clear?

[Ed]

Originally posted by UKBoy1977
She says that the person she liftes was about 12 stone and that she doesn't believe she could lift 3 stone with just her fingers. She performed a variation of it where, instead of just reciting some chant, the 4 people actually pushed down on the persons head and shoulders beforehand. Due to Newton's 3rd law the body of course exerts a reaction force. But she believes the body continues to exert this force after the people have stopped pushing, and this is what made the person feel 'as light as a feather, not 3 stone'

!

This is the same effect that I mentioned above. It has everything to do with opposing muscle groups and nothing to do with newton.

She is suggesting that muscular activity reduces weight. Not. Put someone on a scale and try it.

What is a stone?

[reprise]

We did this "trick" in our PE class in high school, and I can assure you that there's no effort involved in lifting the person (we lifted one of the largest members of our class). As has already been pointed out, you aren't lifting the person for very long at all.

The only thing which I did notice was that our teacher picked as the 4 lifters the people who'd responded best during the relaxation and self hypnosis exercises we'd been doing earlier in the lesson - I don't know whether that information is particularly relevant, but it did stand out at the time.

[zer0vector]

I just did a quick experiment because i was interested, and found that lifting about 45 lbs of weight (about 3 stone) isn't that difficult, as long as your arm position is good.

For example lifting from a position where the arm is almost fully extended isn't much of a problem. However, trying to lift higher when the arm is bent at the elbow about 90 degree is substantially more difficult.

Also, I noticed that most of the actual lifting is done with the arm and shoulder, and all the fingers do is stay straight.

I would chalk this stunt up to clever placement of the people in certain places around the liftee, as well as the lifting from positions where their arms are the strongest. (ie standing on stools, or having taller people lift from positions that are more difficult for short people). I'd say try this out yourself, and see what you think.

[Rolfe]

Originally posted by reprise
We did this "trick" in our PE class in high school, and I can assure you that there's no effort involved in lifting the person (we lifted one of the largest members of our class). As has already been pointed out, you aren't lifting the person for very long at all.


We did this at school too, though not in class. It's easy. And I don't think (apart from the giggles) that any one of us really thought there was anything paranormal about it.

What happened was that the minute the person was off the table, they cracked up giggling. This meant that they weren't held for more than a couple of seconds. If they had stayed still, and been supported, I think our fingers might have got tired rather quickly.

Rolfe.

[tracer]

Originally posted by Ed
What is a stone?
As UKBoy1977 mentioned, a stone is a British unit of weight equal to 14 pounds. You know how, when someone asks you how tall you are, you don't say "68 inches," you say "5 feet and 8 inches" (or just "5 foot 8")? Well, the Brits do the same thing for weight. They don't say "I weigh 136 pounds," they say "I weigh 9 stone and 10 pounds" (or just "9 stone 10").

I learned this from Bridget Jones's Diary.

[plindboe]

Originally posted by tracer

As UKBoy1977 mentioned, a stone is a British unit of weight equal to 14 pounds. You know how, when someone asks you how tall you are, you don't say "68 inches," you say "5 feet and 8 inches" (or just "5 foot 8")? Well, the Brits do the same thing for weight. They don't say "I weigh 136 pounds," they say "I weigh 9 stone and 10 pounds" (or just "9 stone 10").

I learned this from Bridget Jones's Diary.

Well, what is a pound then? :D

[plindboe]

Originally posted by UKBoy1977
She performed a variation of it where, instead of just reciting some chant, the 4 people actually pushed down on the persons head and shoulders beforehand. Due to Newton's 3rd law the body of course exerts a reaction force. But she believes the body continues to exert this force after the people have stopped pushing, and this is what made the person feel 'as light as a feather, not 3 stone'

This is hilarious! :roll:

[max]

a pound is about 500grams

[The Mighty Thor]

I wonder how many so-called home educators are like this kid's mum? Doesn't bode well for the future:

Today's Lesson: Mom's explanation of how Jesus was able to walk on water.

I applaud the poster's sceptical thinking, however.

malc

[hammegk]

Originally posted by plindboe


Well, what is a pound then? :D

A pint of water is damn close (if you know what a pint is;) ).:D


Max kinda beat me to it, but also 1 lb= 1/14 of a stone! :wink8:

[Ninas grandpa]

Originally posted by hammegk


A pint of water is damn close (if you know what a pint is;) ).:D


Max kinda beat me to it, but also 1 lb= 1/14 of a stone! :wink8:

Hmmm...
"A pint of water weighs a pound and a quarter"
in this part of the world.

[glee]

Originally posted by Ninas grandpa
Hmmm...
"A pint of water weighs a pound and a quarter"
in this part of the world.

Two and a quarter pounds of jam weighs about a kilogram. *



*just thought I'd mention that...

[Rat]

A UK pint is 568ml, a US pint is 473ml. So in one country I drink ten pints a night, and in another I drink 12.

A pound is 454g anywhere.

Cheers,
Rat.

[Ed]

Originally posted by ratcomp1974
A pound is 454g anywhere.

Cheers,
Rat.

Thought it was 100p:confused:

[Rat]

Originally posted by Ed
Thought it was 100p:confused:
Or 240d
Or 20s

Cheers,
Rat.

[De_Bunk]

Just a quick thought...

Leave home as quick as possible and have your mother committed..

DB

[thaiboxerken]

Due to Newton's 3rd law the body of course exerts a reaction force. But she believes the body continues to exert this force after the people have stopped pushing, and this is what made the person feel 'as light as a feather, not 3 stone'

This shows a serious ignorance of physics. Why would Newton's 3rd law only work part time? LOL. Your mom should go back to school.

[Jon_in_london]

Interesting.. we did this at school one night, after loads of booze and ganja....

A guy sat on a chair and we all closed our eyes and hummed...then lifted him on the chair with two fingers of each hand. Suprisingly easy.

We tried it again without the humming nonsense and it was much more difficult to lift him.

The simple reason is the humming, chanting mutual masturbation or whatever the fook you do beforehand simply serves to focus your mind. Nothing paranormal to see there...

[Zaphod]

This was covered on Secrets of the Physics recently on British TV. The pretent psychic showed exactly how this is done.

First, to prove levitation is not happening, they put the whole group of people on some scales, and the weight did not drop during the "levitation".

The secrets seem to be:
1. tell the people it is impossible to make them feel weak
2. fail to lift person, due to lack of committment and worry about hurting the person in the chair.
3. boost confidence of lifters with all the psychic bull etc - tell them it WILL work now
4. people try harder second time, with more confidence, and lift person quite high, but for very short duration

Zaphod

[The Mighty Thor]

I know that there is a good physics explanation for this apparent miracle.

Can anyone remember it? It may have been in 'Magic for Dummies' which I can't find at the moment.

malc

[tracer]

Originally posted by ratcomp1974
A UK pint is 568ml, a US pint is 473ml. So in one country I drink ten pints a night, and in another I drink 12.

A pound is 454g anywhere.
Unless you're talking about a pound Troy, which is 373 grams.


And, to pick a nit here, 454 grams isn't the same thing as a pound, 454 grams merely weighs a pound at the surface of the Earth. Grams measure mass, while pounds measure weight.

[tracer]

Originally posted by Jon_in_london
A guy sat on a chair and we all closed our eyes and hummed...then lifted him on the chair with two fingers of each hand. Suprisingly easy.

We tried it again without the humming nonsense and it was much more difficult to lift him.

The simple reason is the humming, chanting mutual masturbation or whatever the fook you do beforehand simply serves to focus your mind. Nothing paranormal to see there...
I learned a similar trick once involving making a loop with your fingers: Have person A put the tip of your thumb and forefinker together in an "ok" sign.
Have person B else hook his forefinger through the thumb-and-forefinger loop of person A's hand. Tell person B to be ready to pull really hard and try to have his forefinger "break through" person A's finger-loop (i.e. by pulling hard enough that the tips of person A's thumb and forefinger are pried apart).
Tell person A to resist person B's attempt to break through person A's finger-loop.
When person B pulls, he'll be able to break out of person A's finger-loop in a couple of seconds.
Have them do it again, but this time tell person A to envision an "energy circuit" flowing through his fingers keeping them together.
This time, person B will probably not be able to break through person A's finger-loop at all.How did this "miracle" work? Did person A's envisioning of an "energy circuit" on his fingers really cause some mystical force to keep them together?

No.

The first time person A tried to resist person B's finger-pull, he instinctively concentrated on keeping his fingers rigid. When you keep an arm or a finger rigid, you actually contract the muscles on both sides of the bone. (Try it. Flex your bicep. You'll fing yourself keeping your arm rigid so that the bicep bulges -- which means your tricep is actually fighting your bicep.) So, not only were the muscles clamping person A's fingers closed engaged, so were the muscles on the opposite sides of his fingers. Person A was literally fighting against his own muscles!

The second time, however, person A wasn't concentrating on keeping his fingers rigid. When he resisted person B the second time, only the muscles clamping his fingers closed were engaged. This dramatically increased the amount of force person A could apply between his forefinger and thumb. He could have accomplished the same thing by concentrating on clamping his fingers together as hard as possible -- as long as he wasn't concentrating on making the finger-loop "rigid".

[BayAreaGuy]

Looks like I'm coming to the party late on this one, but I want to say a few things.

First of all, I'm shocked by how many of you took the trouble to post responses to this fairly straightforward question, but said absolutely nothing. People seem to want to share their own silly, painfully detailed stories rather than answering the person's question.

Second, it's amazing how few of you took the time to read any of the other posts before posting your comments. Repetition on this site is overwhelming and annoying. I don't expect people to read every comment, but at least read enough to make sure you're not restating something that's been said a half dozen times.

More to the point, if you read Randi's work, you'll find perfectly good explanations for the "Light as a Feather" parlor game. I think it's even covered in Flim Flam!, if I recall correctly.

The short explanation is that, on the first try, the motor cortex is unprepared for how much exertion will be required to lift the person. (That's why they always begin with a "see how hard it is to lift her/him?" first attempt.) The second time, the brain has made a calculation based on the first try, and those doing the lifting unconsciously exert more energy and the person lifts easily.

Since the whole process occurs outside our awareness, people gladly fill in the blanks with a lot of woo-woo nonsense, and partygoers eat it up. Unfortunately, far too many take it seriously for the rest of their lives. I hear this example from my students a lot when they're looking for evidence that the paranormal world exists. It's sad.

[BayAreaGuy]

I'm just glad this woman isn't an American, or we'd have to suffer through another round of "aren't Americans stupid?" comments.

Our country may be overrun with self-described evangelicals, but Europe is loopy for psychics, mythical creatures, homeopathy, and a wide array of woo-woo garbage. Verification came this month with Dawkins' Channel 4 special "Enemies of Reason." I laughed my arse off!

[-Fran-]

First of all, I'm shocked by how many of you took the trouble to post responses to this fairly straightforward question, but said absolutely nothing. People seem to want to share their own silly, painfully detailed stories rather than answering the person's question.

You might be easily shocked ;) But really, what is wrong with that? Why can't people share their "silly" stories? Is there a rule against that in this forum? I don't think anyone are under any obligations to answer anything in any particular way, except for keeping it civil.


Second, it's amazing how few of you took the time to read any of the other posts before posting your comments. Repetition on this site is overwhelming and annoying. I don't expect people to read every comment, but at least read enough to make sure you're not restating something that's been said a half dozen times.

I agree that there are often repetitions though, even if I don't find it quite as annoying as you seem to do.

[Ove]

[QUOTE=tracer;271576]Unless you're talking about a pound Troy, which is 373 grams.

Or a Danish Pound which is exactly 500g. :)

But i've done that trick back in scool too and it IS simply because the 4 people work in unison and if you want to convince someone, make the ecperiment with the testperson sitting on a scale. Read it and note his weight and then get the four peolpe to place their hands on his head. Then when they take their hands of his head, instead of lifting the bloke, read the scale... (badaboom)

[Big Les]

Looks like I'm coming to the party late on this one, but I want to say a few things.

Oh, only about four years or so. :eye-poppi

Second, it's amazing how few of you took the time to read any of the other posts before posting your comments. Repetition on this site is overwhelming and annoying. I don't expect people to read every comment, but at least read enough to make sure you're not restating something that's been said a half dozen times.

More to the point, if you read Randi's work, you'll find perfectly good explanations for the "Light as a Feather" parlor game. I think it's even covered in Flim Flam!, if I recall correctly.

Yes it is. As pointed out by the thread starter in the opening post...
Anyway I told her how it is just a case of the weight being distributed over 4 people and them being in a position which gives them good leverage (as explained in Flim Flam!) but she's not buying it.

Perhaps if you read "ukboy77"s work... ;)

The short explanation is that, on the first try, the motor cortex is unprepared for how much exertion will be required to lift the person. (That's why they always begin with a "see how hard it is to lift her/him?" first attempt.) The second time, the brain has made a calculation based on the first try, and those doing the lifting unconsciously exert more energy and the person lifts easily.

Nice concise explanation. But we could have done without the preaching I think, especially given the great antiquity of the thread.

[PenguinWarrior]

Second, it's amazing how few of you took the time to read any of the other posts before posting your comments. Repetition on this site is overwhelming and annoying. I don't expect people to read every comment, but at least read enough to make sure you're not restating something that's been said a half dozen times.



Anyway I told her how it is just a case of the weight being distributed over 4 people and them being in a position which gives them good leverage (as explained in Flim Flam!)





More to the point, if you read Randi's work, you'll find perfectly good explanations for the "Light as a Feather" parlor game. I think it's even covered in Flim Flam!, if I recall correctly.


Ahem.

[Thing]

I'll add my silly story:

In one of his books Isaac Asimov puts forward the view that the way in which Newton stated his 3rd law, "For every action there is an equal and opposite reaction" was a bad way of putting it, as ever since some people have interpreted it as meaning that first you do the action, then the reaction happens.

[Goshawk]

I'm shocked by how many of you...

...it's amazing how few of you...

...if you read Randi's work, you'll find...


You're castigating people for things they said four years ago. "Late to the party"? Um, no, the party was over a long time ago, chairs all put away, kitchen cleaned, doors locked. ;)

UKBoy hasn't posted at JREF since September 2006.
Zer0Vector left in September 2004.
Ed hasn't been here since March of 2006.
Reprise left in September 2004.
The Mighty Thor hasn't been here since July 2005.
NinasGrandpa left in February 2004.
Glee left in October 2005.

Hammegk is, of course, banned.

Zaphod hasn't been around since March.
Max hasn't been around since last June.

Rolfe, De Bunk, Thaiboxerken, Jon in London, and Tracer are, blessedly, still here, as are Plindboe and Rat.

Next time you want to bump a really, really old thread, don't bother addressing yourself to previous posts that, coming in late, you may discover you disagree with--odds are, the posters aren't around to hear you anymore. Just limit yourself to any useful contribution. ;)

[Silly Green Monkey]

Not only is the party over and cleaned up, but I think the people who threw it have moved house!