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The Most Beautiful Experiments in Physics
TheMatt writes "In this month's 'Physics World', Robert P. Crease asks the question: what is
the most beautiful experiment in physics?
Some criteria quoted are that it must change what people thought, must not be too complicated or expensive, and, most importantly, be within the reach of students (which leaves out Stern-Gerlach or Michelson-Morley). He also has a page at BNL reprinting the article, with a
place for suggestions from the community on their opinion." I'll nominate a simple one: Foucault's Pendulum. :)
I once saw an experiment where a small bag made out of thin plastic was subject to the forces of a small pocket of circular wind currents.
Sometimes there's so much beauty in the world, I just can't take it.
I like the idea of exploring colored lasers.. especially synched up to Pink Floyd music ;)
Moderation: Put your hand inside the puppet head!
...comic book breasts. They break at least 3 laws of physics every day.
Kids these days. They don't know the difference between classic, and just plain old.
What about Gallileo's hypothesis about the Feather and the Hammer that was proven on the (IIRC) Apollo 14 mission?
Good quote, too many chars. Seriously, the slashdot 120 char limit sucks!
My vote (without reading other comments) goes to Arthur Eddington's validation of Einstein's relativity by demonstrating that the sun's gravity bent the light from nearby stars. But how do you see stars when they're right next to the sun? Good lateral thinking, very ingenious...
"None are more hopelessly enslaved than those who falsely believe they are free." -- Goethe
Henry Cavendish did an experiment to measure the gravitational constant G. He used a torsional pendulum with two small lead weights to measure the gravitational attraction of two large lead weights nearby. I did this experiment as an undergrad and got a pretty good value for G (big error bars though). It's amazing that back in the 1700s he could measure the gravitational force due to a lead ball.
I just did a google search on "Cavendish experiment" and found this. Evidently a geologist named John Michell deserves some credit too.
Uh, what's the target group? I teach general freshman physics at my university and discuss both SG and MM experiments in detail.
Anyway, I nominate the first nuclear explosion as the greatest ever experiment. Until a hole is successfully opened in the spacetime, splitting the atom is the greatest scientific achievement ever.
There is, in fact, a fabulous book on this subject. What makes it such a great book is that it doesn't depict the making of the atomic so much as a rigorous scientific project, but rather as a social, political, random and very much a human achievement.
The owls are not what they seem
...has to be a front-runner here. Something as simple as a piece of paper and a light source showed that classical mechanics was not enough to explain our universe and that quantum mechanics had to be invented. No computers needed, no complex aparratus, and no genius needed to explain it (today).
;-)
Course, I am a physics freak. The biology, computer science, chemistry, etc. freaks may have their own opinions!
The two slit experiments are the most beautiful. With a simple apparatus it can be shown that light is a wave. With the same apparatus, it can be shown tha light is a particle. And that's not all folks...
The experiment reveals that there's something very very weird happening with very small particles. It could be another universe, or maybe an infinite number of universes. Or maybe just one really weird one. Time itself doesn't seem to have any meaning - things happen for no reason at all, uncaused.
These experiments even seem to reveal something about ourselves. Philosophers and cranks are attracted to the results like moths, offering their own explanations for what is happening, ranging from the hand of god to the basis of intelligence.
The strangeness revealed by the two slit experiment could also form the basis of future computers, where all calculations happen at the same time, but you can't look at the result without destroying the entire computer.
If that whole mess isn't beautiful, I don't know what is.
If tits were wings it'd be flying around.
In this experiment, tiny drops of oil are suspended in mid-air between two charged plates by the interaction of a discrete electric charge on the oil drop.
You use a microscope to measure the speed of the drop with no charge on the plates, then adjust the charge on the plates to hold the drop in place. In other words, the force of gravity is cancelled by the electrostatic force.
If the drops are small enough, you can notice discrete steps in the data when you plot the variables. The beauty is in its simplicity: Using some oil, two pieces of metal and microscope, you can determing the charge of a single electron.
It doesn't get much prettier than that.
Muerte
I always liked how helium balloons go the `wrong' way in a vehicle. toward the rear when braking, rightward when turning rightward, etc. And how General Rel holds the simplest explanation: gravity is indistinguishable from acceleration.
The Pitch Drop Experiment.
If you check the site out, you will even find a live RealVideo stream of the pitch.
Pitch (a derivative of tar once used for waterproofing boats) feels solid at room temperature, and it can easily be shattered with a blow from a hammer. However, at room temperature it is actually fluid.
Quoting from the website:
"In 1927 Professor Parnell heated a sample of pitch and poured it into glass funnel with a sealed stem. Three years were allowed for the pitch to settle, and in 1930 the sealed stem was cut. From that date on the pitch has slowly dripped out of the funnel - so slowly that now, 72 years later, the eighth drop is only just about to fall."
What were the skies like when you were young?
The best experiment is really a pair of them: Young's double slit experiment, and the photoelectric effect. Young's double slit experiment showed that light acted as a wave. The photo-electric effect showed that light acted as a particle. Together they showed that light acts completely unlike anything we experience in the classical world.
Both are simple, easily doable in the laboratory for undergraduates, and after doing (and comprehending) both you'll never again think the same way about light.
One of the first experiments we did at UMR was to measure the acceleration of gravity. It was a weird contraption of a clothespin wired to a switch that started a timer when you released this badminton birdie from the clothespin.
We dropped the birdie onto a box with a microphone in it that stopped the timer when it heard the "thud". We dropped it from different heights and measured the time to fall and then plotted the results.
The beautiful thing wasn't learning that gravity is 9.8 m/s^2, but in showing us that from a fairly simple setup we could quantitatively measure something important in physics. We calculated the acceleration of gravity as well as the terminal velocity of the birdie. And our results were correct!
This was a great foundation to other experiments with interferometers measuring the wavelength of a laser, pendulums, exponential decay (of you name it -- cooling, capacitor discharge, etc.).
Eratosthenes accurately estimated the diameter and circumference of the earth with a stick. That's beauty.
It doesn't necessarily take physics to change a man's worldview:
The Cointoss Fractal
Get a largish sheet of paper, a coin or a d6, a felt-tip marker, and a tape measure.
Draw three dots, making any given shape of triangle. Pick any dot at random. This is your first point. Use the coin or a d6 to *randomly* decide between all three dots as a second point. Draw a new dot exactly half-way in between the two points. Use the dot you just drew as your new first point. Use the coin or a d6 to randomly select a new second point. Draw a dot exactly half-way between the two points. Wash, rinse, repeat.
After even a few hundred iterations, you'll begin to see a beautiful crystaline-like fractal pattern emerge. Even with the inherent innacuracy of this method, you can see the fractal down to the fourth or fifth iteration of the pattern before it breaks down. If you use even a slightly more accurate method, such as a C or Pascal program to draw colored dots on a computer screen, you can get 10 or 11 iterations, even with interger math rather than floating point.
The first time I saw this, I very nearly cried.
Order from chaos, just from math.
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
Nuclear fission...
ok then your [sic] infringing on my copyright! Could you as [sic] me next time before STEALING my comments for your own?
One of my favorites is Newton's experiment which is as simple as a ball on a track. Noting that gravity was apparently a force to be considered, Newton showed that since the ball accelerates if the track is tilted down and deccelerates if tilted up, that objects under no force (track perpendicular to gravity gradient) should neither accelerate or deccelerate.
Also, the related experiment using wires spaces n^2 distances apart, and listening for the resulting equal times between "clicks", which shows that the distance covered is proportional to the square of the time!
And then, how about Newton's extrapolation of the laws of gravity (observed by simple things like falling bodies) to the laws governing celestial bodies under the influence of gravity? This is pretty impressive, I think, to be able to predict successfully something that has no (near) physical equivalent that you were able to test beforehand!
dropping a bowling ball and a light foam ball to demonstrate how mass is independant of gravity.
You could do this with material from a smoke detector and some fluorescent screens.
He sent a beam of alpha particles through a target, which according to the theories of the day should have been like firing a bullet through jello.
Some of them bounced straight back, which proved there were small hard objects in the "jello". Those small hard objects were atomic nuclei, and the experiment revealed the existence of matter with unprecedented density.
I have taught undergraduate differential geometry many times, and covered the relevant material (parallel transport of vectors along non-geodesics, holonomy) and frequently even reasonably strong students have a hard time with understanding it correctly. Particularly when I put a parallel transport question on an exam...
This Smithsonian FAQ has a bit about pendulums, but just says the relationship is complex. The California Academy has a page that is much better than a typical museum explanation in that it mentions that the amount of precession depends upon latitude and gives the relationship (precession is 2 pi sin(phi) where phi is the latitude) as well as making a reasonable effort at an explanation.
It's psychosomatic. You need a lobotomy. I'll get a saw.
Definetly.
What other experiment changed the world more in such a simple way as to drop 2 objects of diffrent Mass and show that gravity acts the same for each?
Archamedies I guess would also be. sitting in a tub to proove that diffrent densities displace diffrent amounts of water.
I am the Alpha and the Omega-3
Ok, so this is probably apocryphal, but I was sent this a while ago:
A question in a physics degree examination at the University of Copenhagen
ran thus:
"Describe how to determine the height of a skyscraper with a barometer."
One student replied:
"You tie a long piece of string to the neck of the barometer, then lower the
barometer from the roof of the skyscraper to the ground. The length of the
string plus the length of the barometer will equal the height of the
building."
This highly original answer so incensed the examiner that the student was
failed immediately. He appealed on the grounds that his answer was
indisputably correct, and the university appointed an independent arbiter to
decide the case. The arbiter judged that the answer was indeed correct, but
did not display any noticeable knowledge of physics. To resolve the problem
it was decided to call the student in and allow him six minutes in which to
provide a verbal answer which showed at least a minimal familiarity with the
basic principles of physics. For five minutes the student sat in silence,
forehead creased in thought. The arbiter reminded him that time was running
out, to which the student replied that he had several extremely relevant
answers, but couldn't make up his mind which to use. On being advised to
hurry up the student replied as follows:
"Firstly, you could take the barometer up to the roof of the skyscraper,
drop it over the edge, and measure the time it takes to reach the ground.
The height of the building can then be worked out from the formula H = 0.5g
x t squared. But bad luck on the barometer.
"Or if the sun is shining you could measure the height of the barometer,
then set it on end and measure the length of its shadow. Then you measure
the length of the skyscraper's shadow, and thereafter it is a simple matter
of proportional arithmetic to work out the height of the skyscraper.
"But if you wanted to be highly scientific about it, you could tie a short
piece of string to the barometer and swing it like a pendulum, first at
ground level and then on the roof of the skyscraper. The height is worked
out by the difference in the gravitational restoring force T = 2 pi sqrroot
(l / g).
"Or if the skyscraper has an outside emergency staircase, it would be easier
to walk up it and mark off the height of the skyscraper in barometer
lengths, then add them up.
"If you merely wanted to be boring and orthodox about it, of course, you
could use the barometer to measure the air pressure on the roof of the
skyscraper and on the ground, and convert the difference in millibars into
feet to give the height of the building.
But since we are constantly being exhorted to exercise independence of mind
and apply scientific methods, undoubtedly the best way would be to knock on
the janitor's door and say to him 'If you would like a nice new barometer, I
will give you this one if you tell me the height of this skyscraper'."
The student was Niels Bohr.
A great example of how there are always different ways of looking at a problem, from one of the greatest scientists ever (allegedly).
We had finished our lab a bit early, and well, there was still about 3 gallons of unused liquid nitrogen -- this could not be allowed. So we started to figure out things to do with it, poured it on the floor and watched the dirt particles dance around :)
Looking for some other things to do with the stuff, I poked some holes in the bottom of our Styrofoam cup and poured the liquid nitrogen in it -- I had hoped the cup would levitate on the boiling nitrogen leaking out the bottom ... no dice, it was too heavy -- So I kept tearing away the walls of the cup, trying to leave enough room for liquid nitrogen, but leave the cup light enough to float. Finally I arrived at the right balance, and we had fun kicking our cup around the floor and watching it glide. So to be idiots we showed the TA what we were doing and he replies, "Gentlemen, you have just discovered the leidenfrost effect." And to this I reply, "We call it hovercup."
Religion is a gateway psychosis. -- Dave Foley
One of the simplest and most compelling experiments to my mind is the "drop a feather and a penny in a vacuum tube" demo. There is a nice one at the Exploratorium in San Francisco- an evacuated tube with a metal ball and a feather, pivoted in the middle. Sure enough, when you turn it over, they fall at the same rate. I found it surprisingly addictive and fascinating and always have to elbow a bunch of kids out of the way to get to play with it for very long...
It's psychosomatic. You need a lobotomy. I'll get a saw.
It is relatively easy to establish, has great application and it has very reproducible results as shown by many groups arround the world.
Wait a minute...
There are a whole class of experiments where old masters using (by modern standards) primitive equipment found results that were accurate even to modern standards and formed the basis of modern science:
The archive:h tml
http://www.jsc.nasa.gov/er/seh/feather.
and some old video:
http://www.jsc.nasa.gov/er/seh/feather.avi
Good judgement comes from experience, and experience comes from bad judgement.
- W. Wriston, former Citibank CEO
Not regularly repeatable. But one of the first experiments to support general relativity was brilliant.
1) Look position of stars
2) Wait for solar eclipse
3) See that stars near moon have moved from where they should be.
IANAP but I once saw a student at a science fair who measured the charge of an electron using standard off the shelf high-school lab equipment.
Instead of the very pure oil used by Millikan she used cooking oil. This introduced a lot of noise in the system, but quite amazingly when you plot out the results you can clealry see the impure oil component and the electron charge component. Subtract the impure oil component from your data, average out and report the result. She got the charge of the electron right to three significant digits of precision IIRC.
Michelson-Morley had to do with the existence of aether. It was complicated, but elegant.
;-)
But Michelson had already done an even more historically impressive experiment, I think, that had to do with the most accurate measurements of the speed of light in his day by far. "In 1878 Albert A. Michelson first accurately measures the speed of light with $10 worth of apparatus along the seawall" (scroll toward the middle of the page).
The more accurate measurement he made in the 1920s is described briefly below that quote on the same page. Certainly the $10 experiment is in the grasp of most classrooms, but I think the mountaintop one is also possible for today's students, what with GPS and all, or even a really good topo map (+/- a few feet gets you close-enough-for-proof-of-concept). You have to get 2 teams of kids on 2 different mountains- and with SUVs and the quality of roads nowadays, how hard is that to do in the high sierras with some adult supervision? Maybe hard to do if you live in Kansas, admittedly.
Plus, what school kids want to sit around a stuffy lab? How cool an experiment would it be to the most science-jaded student to get out of the classroom and into the wilderness to do science on an as easily appreciated concept as the speed of light?
Here's another good article on the history of the speed of light and better details of Michelson's efforts.
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
If anyone still remembers their old junior high (maybe even high school and college!) text books, they'll never forget the "Shoot the Monkey" experiments that proves projectile motion and more simply that gravity is not governed by mass.
In a nutshell, drop an object with just gravity effecting it's fall and aim a projectile at it, since they fall at the same rate, the projectile will hit the falling object every time.
Of course, they always use a falling monkey and a sling shot in the text books, it just cracks me up.
You can't beat Schrodinger's Cat!
"To talk of many things:
Of plastic foam--and tuna cans--
Of chunks of lead--and string--
And how the force of gravity--
Will make the balance swing."
The above is from John Walker's excellent website. He conducted the Cavendish experiment in his basement.
- Monica
When I was in school, this was the most fascinating thing that I ever read about. Simple mirrors and rotation. Ofcourse, the Young's double slit experiment is also fascinating, but I didn't understand it when I was in School :)
s / pedlite.html
More info at a link I got from Google: http://www.phys.virginia.edu/classes/109N/lecture
S
I was thinking of the pencil test :-)
Oh, come, come, come. Without a monster or two, it's hardly a quest... merely a gaggle of friends wandering about. - Owl
I wrote a paper last year entitled "On Mathematical Beauty", which was mostly a philosophical work on whether it was proper to mathematics to be called beautiful, and if so, what one might mean by calling a particular bit of mathematics "beautiful".
So in light of that, I'm interested in seeing what people mean when they say that a physics experiment is "beautiful". If we can figure out what we mean by that (i.e., whether we mean "beautiful" in the same way as when we call a car or woman or building "beautiful"), then maybe that will help us decide which is the *most* beautiful.
Belloc
I got more rhymes than Jamaica got Mangoes.
Fermi problems cover virtually any area of physics and serve to train the most fundamental part of being a physicist- the ability to think as one. From simple things, like the average energy imparted to your forehead by a single raindrop, to calculating the strength of a nuclear explosion from the drift of paper shreds, Fermi problems emphasize efficiency of logic and intuition to understand the natural universe.
Eratosthenes accurately estimated the diameter and circumference of the earth with a stick. That's beauty.
Quite right. This beautiful experiment is explained and recreated in Carl Sagan's Cosmos series. Not only that, but Eratosthenes did this many years Before Christ. By the time that Christopher Columbus petitioned the royal court for funding for three ships to sail westward from Portugal to India, scientists already knew the circumference of the earth pretty damn well. Well enough to know there was no way in hell Columbus would ever make it. But in 1492 -- and this is still true today, unfortunately -- the intelligent advice of scientists was disregarded by the rulers were blinded by visions of wealth and power and the Queen funded Columbus' journey. Turns out, unbeknownst to anyone, that Columbus' ass was saved because there was a land mass closer than halfway. Columbus decided that since he had sailed west to get to India, and ran into some land, had indeed reached India and proclaimed the inhabitants Indians -- a misnomer which exists to this day.
Although Eratosthenes was a true genius the world hails Christopher Columbus as a hero even though his accomplishment was sheer accident. What does this tell you about how the world views science and scientists?
GMD
watch this
I have always been a fan of the monkey in the tree experiment.
The setup story goes like this:
There is hunter walking through the forest, and he sees a monkey in the distance in a tree. He shoots at the monkey. Well, the monkey is so startled by the gunshot that he falls out of the tree at the same instant that the gun is fired. The bullet still hits the monkey. How is this so?
Basically this takes advantage of the fact everything falls at the same rate. You set up a gun of some sort (with a round projectile), and you set up a "tree" with the monkey a distance way. The gun and the monkey should be at the exact same height. The trick is to then fire the gun and drop the monkey at the same instant. The projectile should hit the monkey every time.
This experiment is a pain to get setup correctly, but it is pretty cool when it is successful. I couldn't find any video of it on the web, maybe somebody else can find some.
Do you have Linux and a DotPal? Click here now!
I think that any experiment that makes people think "outside the box" can be called beautiful.
I forget what this one is called, but it goes something like this:
You have a light source on one end. Screen on another (a fairly long rail connecting the two.
Put a piece of horizontaly polarized glass between light and screen - the intensity of light on the screen is cut in half.
Add another piece of (vertically this time) polarized glass - there is virutally no light going through.
Lastly - add a piece of polarized glass that's at about 45 degrees half way in between the other two. What do you expect to see on the screen?
Two slit interference, on the other hand, is a perfect case of what they're looking for. Of course, whether overturning existing ideas is a prequisite for beauty is another issue...
In molecular biology, I'd nominate the Crick and Brenner determination of codon size as the most beautiful ever.
What I'm listening to now on Pandora...
Sir Issac was not "sitting" under a tree; in fact, he was lying down, and he was sound asleep.
It wasn't just any apple which happened to fall onto him; it was a rather large apple, which fell because it had gone thoroughly rotten to the core.
And Newton did not say "I've discovered Gravity", but rather just commented "the world sucks."
The thing about things we don't know is we often don't know we don't know them.
it is an amorphous solid, refer to this urban legend...
An Urban Legend
The legend usually appears in any of the following forms:
Antique windowpanes are thicker at the bottom, because glass has flowed to the bottom over time.
Glass has no crystalline structure, hence it is NOT a solid.
Glass is a supercooled liquid.
Glass is a liquid that flows very slowly.
Glass is a liquid.
The prolonged survival of this legend, chiefly among English speakers (and particularly among North Americans) is puzzling -- especially when one considers that glass and glassy materials are readily available, and one can easily verify if one can pour a gallon of glass, or drain a pint of obsidian.
https://www.accountkiller.com/removal-requested
OK first the reason for the asterisks - if you ask about Foucault's Pendulum on the Model Eng mailing list, you WILL cause a stink - it caused the longest running thread a few years back
Anyway doing Foucault's Pendulum is NOT easy. You need a LONG Pendulum, a SOLID building, a heavy bob and preferably no drafts
The Gent on the ModelEng list tried to do it in an old barn silo, and it didn't work, as the silo moved too much
BTW I was told that research at the University of Quito has shown that the Foucault Pendulum doesn't work
-- 73 de KG2V For the Children - RKBA! "You are what you do when it counts" - the Masso
Eratosthenes' experiment notwithstanding, sailing ships taught us the world was round in a very accesible way... on a clear day, the hull of the boat dissapears over the horizon before the crow's nest does.
Brant
Argle. Bargle.
I recall setting up a transparent cuboid (glass or perspex, I forget) to totally internally reflect light off one of its faces. When a second transparent cuboid was placed very close to the reflecting face, some light passed from the first cuboid into the second, and was visible coming out of the second cuboid. It happened even though the two blocks were not quite touching. This is a very simple way to demonstrate quantum tunneling.
Any sufficiently self-referential snowcloned
If you want beauty, I vote for fractals and chaos mathematics, and their applications. How 'bout diving into the Mandelbrot set?
There's also an experiment you can try if you have a handy particle accelerator; defocus it and fire some electrons at a sheet of lexan. Then touch a grounded wire to the side of the sheet. The electrons, embedded into the face of the plastic will rush to ground, creating pathways that other electrons will follow. The result is a fractal tree. You may have to play with the intensity and run-time, though.
Remind me why students can't build an interferometer, again?
My old high school had all of the required equipment (had a holography lab at one point).
I don't know if this really counts as changing the way people think about science, but it certainly changed the way I thought about my Science teacher...
The "classic" version of the experiment is to fill a steal ball with water and seal it shut. If you place the ball in the freezer, the next day you'll find that the force of crystallization was stronger than the steal and the ball will be split in two.
My High School physics teacher got a hold of some liquid nitrogen and wanted to do whole experiment during class. So he prepared the steal ball, filled a glass beaker (yes, glass) with the liquid nitrogen, and set the ball in. As everyone gathered around up close to watch, he did have a brief moment of sanity and decided that, perhaps he should move the whole thing into a bucket instead. And maybe we shouldn't stand quite so close. So he poured the whole thing into a plastic (yes, plastic) bucket, added more liquid nitrogen to account for the increased volume, and we waited.
The force was not only enough to break the steal ball, but enough to shatter the bottom of the bucket too. He didn't have enough liquid nitrogren left to demonstrate that a rose will shatter if frozen, but we kinda saw that effect already...
-- Don't Tase me, bro!
You are disputing the fact that light behaves both as a particle and as a wave?
That flies in the face of a great many years of modern physics you know.
Saying they are particles that propgate as waves is innacurate, of course.. it is merely light, and exhibits properties of both.
So.. given that any other particle can also be viewed purely as a wave.. does your statement not hold true for all reality?
A proton is a quantized wave.
So is an electron.
Any particle stream behaves as a wave to some degree. The wavelength just gets extremely long as you get away from c, so the effect seems to disappear.
Look, we all went to high school (at least for a little while, I'm sure) so we all know that the best experiments are the ones that end in an explosion. Unfortunately, most of the good experiments are generally regarded as chemistry, and not physics (an atificial distinction, I am aware.)
The very best experiment, however, which certainly satisfied at least the "changed worldview" requirement, took place in the nevada desert in 1945, and was carried out primarily by physicists. Now, two kids go to their science fair:
Cindy - I measured the speed of light by observing jupiter's moons!
Kelly - I have first strike capability!
Who's going to win? I don't know how much enriched uranium you really need to make a nuclear bomb - all published figures are inflated - but they make lawn furniture out of it in the former soviet bloc, so I'm sure you can get some. After that you just need an enclosed container, an explosive, a little engineering knowhow and a healthy contempt for human life. With the plane tickets to and from eastern europe, I anticipate the whole deal costing less than $5,000 US for the fanatically inclined hobbyist. Admittedly, it costs more than a piece of cardboard with slits in it, but it's a lot more satisfying.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
It moves forward, as others said, because the air in the back becomes more dense, the air at the front, less dense, so the helium balloon moves away from the dense area.
The air in the back is more dense because the car is accellerating.
Similarly, the air is more dense near the surface of the earth because of gravity.
And as we all know, gravity and accelleration are indistinguishable (locally).
So. Both cause the balloon (via their effect on the atmosphere) to move opposite the vector the force is applied in.
(In this case, G + accelleration would put it on an angle, but your balloon is on a string.. etc.. etc..)
The most beautiful experiment has to be Newton's light slit and prism showing that white light is actually made up of many other frequencies. From there young minds can be introduced to all sorts of things such as why sticks appear to be bent when half in water and at what angle they seem to disappear. But to really get them going, help them create a hand drawn hologram. http://www.amasci.com/amateur/holo1.html
In Eratosthenes day the general feeling among learned people was that the world was a sphere. His great demonstration was not that- it was estimating the circumference of the earth to a remarkable degree of accuracy.
From memory, some of the more interesting experiments the Amateur Scientist column include:
Tons of goodies, all worth goofing around with. If you can't come up with some good ideas after leafing through this material, you just aren't trying.
There is much pleasure to be gained in useless knowledge.
My favorite from high school was extremely simple. Use a "wave pool" (a pan and a mechanical device that dabs one or two prongs into the water at some frequency). Aim a strobe light at the pool and turn off the lights. When you match the wave frequency to the strobe, the waves seem to stand still. Of course, you are merely catching the flash at the same point on each wave. Move the strobe frequency a little slower and the waves creep out. A little faster and they creep back to the source. Two wave sources, and you get to see the effect of the interference pattern.
Saw this expierement, professor has a rope with a bowling ball tied to the end suspended from a high ceiling. Stand at one end of the room with the ball pulled back and just touching his nose. Professer them lets go of the ball and it swings across the room and returns just missing his nose.
Of course, then stupid studnet comes back later that night to show a friend, holds the ball against his nose and gives it a sold PUSH...
Beautiful.
Krispy Cream is people
Take a fresh, large grape, and cut it in half so that there is still a piece of grape-skin connecting the halves. Place this on a plate, and microwave on HIGH. Watch the pretty light-show.
A similarly interesting, and eventually decorative result, can be achieved by microwaving AOL CDs..
The REAL jabber has the user id: 13196
What you do today will cost you a day of your life
Galileo determined that light took finite time to travel and measured the speed of light. He used a crude telescope that third graders could build (if they bought a 1" lens), a clock, and grade school mathematics. The technique was to measure the time at which the Galilean satelites dissappeared and reappeared from behind the shaddow of Jupiter. Based on the difference between when the moons were observed to (dis)appear when the Earth and Jupiter were on opposite sides of the sun as opposed to when they were on the same side of the sun, we was able to determine that the speed of light was finite, the first step towards the developement of relativity. Of course, his measurements weren't very precise, since he didn't have a great measurement of the distance from the Earth to the Sun. In fact, once we had measured the speed of light in the laboratory, this technique was used to measure the distance from the Earth to the sun. I beleive this was the basis of the best measurements until the advent of radar (timing radio signals bounced off planets) and space probes (feeling the gravity of the planets).
Nowadays, the most likely experiment students would grasp would be the effects of beer.
Seriously though... Anyone who went to UT Austin and took physics would likely have heard of Prof. Rory Coker and his Physics Circus. All sorts of beautiful experiments there. Among them was a demonstration of airflow. Put a three-foot high glass cylinder, open at both ends, over the top of a candle, the cylinder being flat on the table so no air gets in that way. The candle will go out, even though the top is still open. Do it the same way, and slip a simple piece of cardboard into the top of the cylinder, making an "outflow" and an "inflow". Even though the cardboard is maybe six inches long, it's enough to keep the candle from going out.
Then there's the experiment where Coker gets on a bed of nails and has his assistant bust cement blocks on a piece of plywood on his stomach.
Lately democracy seems to be based on the skybox, the Happy Meal box, the X-box, and the idiot box.
Dunno if this one is true, but it stuck in my head as being deliciously elegant..
Supposedly, shortly before WWII German scientists were trying to work out the best shape to use for U-Boats. The solution was as follows:
freeze a big long slab of ice with a rope embedded in it. Store it in a shed beside a long canal during winter. Wait for a day where the temerature of the water in the canal is zero degrees [everything in celsius, for the no-scientific americans among us] but has not frozen.
On the magic day, drop the block of ice in the canal, & start towing it down the canal at the speed you're interested in having your u-boat move at. The friction created by being towed through water creates sufficient energy to crack the latent heat of freezing, the only thing differentiating the zero degree block of ice from the zero degree water around it, & the edges of the ice start to melt, causing the ice to start taking on the optimal minimum drag shape for the speed it's moving through the water at.
Once the shape of the ice seems to have stabilized, you pull the block of ice out of the canal & measure its shape. Voila - you now have the optimal minimum drag shape for your u-boat.
The wave/particle and "acceleration indepency on mass" experiments are great, but I have a great respect for pendulum experiments. With them you can determine the mass of the earth, local gravity, determine that the earth does indeed rotate, mirror the findings of dropping differing masses, etc.. Not to mention that their ability to time events was important for a lot of other experiments.
Actually, this exact question was asked at an Olympics of the Mind competition back in 1990 or so. Teams had to submit as many creative answers as they could.
Answers were fantastic, far more creative than this one, included, but not limited to:
Accellerate the building towards c until it appears the same size as the baromoeter, and use the resulting speed to calculate the original size.
Drop it off, and observe the impact damage it makes to the ground. calculate the forces needed to do this.
Run far away from the building and hold the barometer at arm's lentgh until it appears the same size as the building. DO some trig.
Drop the barometer, and listen for the delay betwen it hitting the ground and the sound reaching you. Calculate height based on speed of sound.
ANd I really wish I could remember some of hte other 50-odd answers that one team came up with... it was fantastic.
And I think the thing about Bohr is an urban legend.
Though not particularly revolutionary, creating a cloud chamber and seeing the paths of radioactive particles is really quite amazing the first time you see it.
We did this experiement during A-Level physics, with small chambers using dry ice, alcohol and some of the small alpha and beta sources that schools are allowed to use.
A quick google seach will turn up lots of instructions for making your own, for example :
- some instructions from cornell
- or an article from Scientific America
although without a radioactive source you'll have to sit around and wait until some cosmic rays create some ionizing radiation that hits your experiment.Didn't I see something here awhile ago about someone trying to proove Schrodinger's Cat by locking a kitten in a boiler with a quickcam diligently watching the outside? Can't seem to find it tho.
Triv
How about superfuidity?
Seriously, that is one of the coolest and creepiest things at the same time, watching liquid helium crawl UP and spill out of a container. Granted liquid helium is rather expensive it is something which should really get the little buggers thinking and doing some research.
--Won't that be grand? Computers and the programs will start thinking and the people will stop. - Dr. Walter Gibbs
I don't think anyone's bothered to do such an experiment with 4-km interferometer arms, since you can demonstrate the wave nature of the electron with a much smaller apparatus. The simplest way is with the analogous 2-slit experiment for electrons -- requires very small slits, and so is generally done instead with a crystal lattice, but the results are just as you would expect.
The way quantum mechanics is formulated -- which, I would point out, does an extremely good job of describing the world as we see it -- absolutely precludes describing anything purely as a particle or as a wave. And that's not even the spooky part
Quantum mechanics: the dreams that stuff is made of.
First year physics - Lancaster, PA Sept 1967
Takes place is a large lecture theater. At one end of the room an empty beer can is suspended from near the roof by an electromagnet. At the other end of the room there is a long iron pipe hooked up to a canister of compresses air. At the end of the pipe there is a electromagnetic relay. Place a ball bearing the the pipe and aim it at the beer can across the room. Push a charge of air into the pipe, the ball bearing flies out of the pipe and as it leaves the pipe triggers the relay which causes the electromagnet to release the beer can. Both the beer can and the ball bearing begin to fall and accelerate at the same rate as the ball bearing flies toward the beer can. BANG. Our very very large physics professor, Prof. Richard Hood (aka happy) is heard to exclaim: "Ain't science wonderful". A true red letter day in a four year foray into college physics.
Answer: nope. We can describe these phenomena perfectly well, in a language called mathematics. Sure it takes some years to gain fluency in, but so does German.
I hope someone said something similar to your friend the philosophy student.
To be clear, I'm not one of those string theorists who claim that reality itself is a mathematical construct, to which we ascribe some "physical" process to make ourselves feel better about it. They would say, write down the equations and that's all there is. Believe me, I know several of them. However, quantum mechanical objects can be completely described mathematically, and as such you can't hope to describe them more precisely in some other language.
Quantum mechanics: the dreams that stuff is made of.
The Thompson experiment, or the modern manifestatin of, is by far my favorite.
Electron gun in a helmholtz coil, where with just a bit of E&M you can figure out the charge to mass of an electron. Very pretty as well, with the glowing electron path being steered into a loop.
Or shooting the falling monkey. It entertains the kids, and really hits home the idea that all things fall at the same rate, no matter how fast they are going laterally.
Getting diabetes AND salmonella would be a bad weekend.
This is a very common misconception. And one of the worst kind, since it's ingrained into all of us as "the correct answer" to another "misconception".
Look at it this way: the bigger an object is, the stronger the force of gravity it exerts. For instance, the sun exerts a whole heck of a lot more gravitational force than the earth. And the moon exerts less, since it is smaller. Now, just because something the size of a golf ball or a feather is very, very, very small, doesn't mean it isn't producing it's own gravitational field.
Now, when compared to the gravitational force exerted by the earth, the force exerted by a golf ball is extremely tiny. Same with the feather. However, the golf ball's gravitational effect is bigger than that of the feather!! So, the total force acting between the golf ball and the earth is greater than that between the feather and the earth.
More massive objects DO fall faster, since gravitational force DEPENDS EXCLUSIVELY ON MASS. Here's the scalar equation for gravitational force on two bodies:
F = G * (m1 + m2) * m2 / r^2
m1 and m2 are the masses of the two objects. If you make either one of them bigger, the force gets bigger. If you keep one the same (the earth) and plug in two values for m2 (a golf ball and a feather) the more massive m2 gives you more force! And substituting in the old trusty F = m * a, we get:
F = m2 * a
m2 * a = G * (m1 + m2) * m2 / r^2
divide both sides by m2, and you get:
a = G * (m1 + m2) / r^2
Which clearly depends on BOTH masses.
What your grade-school science book was trying to tell you (often poorly, hence the misconception-on-top-of-misconception) was that objects of the same mass but different densities would fall at the same rate without the effects of air resistance. (As in, "Which falls faster, a ton of rocks, or a ton of feathers?" NOT "Which falls faster, a cubic meter of rocks or a cubic meter of feathers?")
Anytime an ambulance passes me, I'm amazed. The change in pitch of the sirens so clearly illustrates the Doppler effect.
:)
This must be the most easy experiment to conduct for any student. Just go sit outside a hospital for a couple of minutes.
So when this question came up, I knew this was the one experiment for me
the pun is mightier than the sword
You're using a simplified form of that equation that assumes m1 + m2 ~= m1 (as in the earth+feather case-- one is so small compared to the other it makes almost no difference).
The whole equation is:
F = G * (m1 + m2) * m2 / r^2
Doing the work with F=m*a:
F = m2 * a
plug (m2 * a) in for F in the gravity equation:
m2 * a = G * (m1 + m2) * m2 / r^2
divide both sides by m2, and you get:
a = G * (m1 + m2) / r^2
Such a good story - it's a pity it is not true! Here's a link to David Goodstein's homepage - he's the vice-provost of CalTech - the second link on his homepage is a PDF file which should show you that the accusation is simply wrong.
Take a look - it's not long, and it's well worth it - before slandering a beautiful experiment.
"I will take the Ring," he said, "though I do not know the way."
Something as simple as a piece of paper and a light source showed that classical mechanics was not enough to explain our universe and that quantum mechanics had to be invented.
First, you might want to throw a prism on your list, or a laser, since it only works with monochromatic light. Secondly, this shows the wave nature of light, but it doesn't show the particle nature, so it doesn't really challenge classical physics when taken in issolation. You need something like the photoelectric effect, or an in-depth look at spectroscopy vs. black body radiation in addition to make trouble for classical physics.
-- MarkusQ
This is so cool...
: www.fourthturning.com/forums/viewtopic.php%3Ftopic %3D22%26forum%3D6+ink+rod+glycerin+drop-of-ink+tur n&hl=en.
Bohm further proposed that the holomovement I mentioned consists of two parts - an explicate order and an implicate order. I will clarify this difference with an example that Bohm himself developed.
Imagine a jar filled with thick, transparent fluid-like glycerin, a highly viscous fluid. In the center of the jar is a cylinder rod with a handle so you can turn the rod. You add a drop of ink into the glycerin, and the ink just sits there. But when you turn the inner cylinder around, it pulls this drop of ink and stretches it out. If you continue turning, the ink is drawn out into longer, ever finer and fainter lines. Eventually, if you keep doing this, the ink actually disappears completely. You can no longer see it.
Now at this point, it's very tempting to conclude that the order that was originally present in the drop has now been rendered completely random and chaotic by thorough mixing of the ink into the glycerin. So much so that you can no longer even see the ink. However, if you now reverse the direction of the rotation, what you find is that this thin long line of ink will begin to reappear. And as you continue the reverse rotation, it will continue to get thicker and more clearly defined, and eventually, it will completely reconstruct itself.
Now this is a mechanical metaphor for what Bohm talks about. What it tells us is that a hidden order may be present in what appears to be random. That's a very important insight that Bohm had, so I'd like to repeat it. With reference to this example and with references to reality in general, what appears to be random may, in fact, contain a hidden order. And unless your epistemological net is sufficiently fine, or sufficiently broad, you may miss that hidden order.
Bohm call this order the implicate order, because although the ink is dispersed to the point of not being visible, its order has, in some way, been preserved. Or, I should rather say it's been transformed into a different form, but it has not been destroyed. And it can then move from being implicate into what Bohm would call the explicate order, where the order has been made visible and made manifest. So we than have this ink dot reappearing.
When the ink drop disappears, Bohm would say that its order is enfolded in the glycerin. When the ink drop reappears, its order is unfolded back into the explicate order. I am going to be using these terms, so I want you to be come familiar with them.
Taken from http://216.239.33.100/search?q=cache:rAqZl1UCxFIC
Interview with him about this very thing Here. Read up on this also here.
You quitting proves that the karma kap worked. The most annoying of the whores shut up. --CmdrTaco
Your obnoxious technicalities expose your ignorance.
BZZZT! And thank you for playing! Here's your lovely parting gift.
Yes, the more massive object will hit with more FORCE, but the accelleration (and hence the velocity upon impact) will be the same for both objects.
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
From the Tap Room.
From Scientific American.
And one from Science News.
Now really, how would any of this classify you ask? It is accessible to students (at least I recall accessing a fair amount of it), it changed the way people think (at least about beer, and your eyes are opened to the wonderous presence of physics in everyday life), and if all else fails, you can usually drink your experimental supplies, which would be a damn risky proposition in many other experimental situations....
-- Mal: "Well they tell you: never hit a man with a closed fist. But it is, on occasion, hilarious."
from http://apod.gsfc.nasa.gov/apod/ap010221.html
(Go to the page to see a sonic boom)
"Explanation: Many people have heard a sonic boom, but few have seen one. When an airplane travels at a speed faster than sound, density waves of sound emitted by the plane cannot precede the plane, and so accumulate in a cone behind the plane. When this shock wave passes, a listener hears all at once the sound emitted over a longer period: a sonic boom. As a plane accelerates to just break the sound barrier, however, an unusual cloud might form. The origin of this cloud is still debated. A leading theory is that a drop in air pressure at the plane described by the Prandtl-Glauert Singularity occurs so that moist air condenses there to form water droplets. Above, an F/A-18 Hornet was photographed just as it broke the sound barrier. Large meteors and the space shuttle frequently produce audible sonic booms before they are slowed below sound speed by the Earth's atmosphere."
So why does a bullet make less noise? well, if a sonic boom is the release of built up acoustic energy, then the bullet has two sources of noise to contribute to this: the explosive discharge, and the noise caused by displacing air along it's path.
A jet, on the other hand, has two different sources of noise to build up and then release: A huge, noisy jet engine, and a far greater surface area for air to move over, causing a much louder rumble. This basically means that there is far more energy to turn into a 'boom' than a bullet has. Bigger bullets have a larger explosive charge, and a greater surface area to build up noise to be released on a sonic boom.
So, to state the obvious, a large object creates a large sonic boom, and a small object creates a small sonic boom.
Alcohol, Tobacco and Firearms should be the name of a store, not a government agency.
More massive objects DO fall faster, since gravitational force DEPENDS EXCLUSIVELY ON MASS. Here's the scalar equation for gravitational force on two bodies:
This is either untrue or misleading, depending on whether you define "falls faster" as either "has greater acceleration" or "hits the ground first when dropped from the same height", respectively.
F = G * (m1 + m2) * m2 / r^2
What is this? The equation for the gravitational force experienced is F = G * m1 * m2 / r^2. Where did you get the above non-symetric equation? The force is identical from the perspective of both masses, so how you got the above is a mystery. That equation is nonsense.
Anyway, the acceleration experienced by m1 is (via substitution of F=ma) a1 = G * m2 / r^2.
The acceleration experienced by m2 is a2 = G * m1 / r^2. Note that the acceleration for object one depends only on the mass of object 2, and vice versa. If you add these two accelerations, you get a formula similar to what you ended up with, (a1 + a2) = G * (m1 + m2) / r^2. But note that this is the total acceleration, not a1 or a2, but the sum of both, so it can't be used to get the force equation you materialized.
The grade school book is in fact telling you that, barring wind resistance, a cubic meter of rocks does fall at the same rate as a cubic meter of feathers. It is telling you this because it is true, when you define "falling rate" as "acceleration towards the ground".
Now, what probably confused you is the fact that if you were to drop the bricks and the feathers one at a time, the bricks would indeed hit the ground first. That is because the earth falls up at the bricks faster than toward the feathers. But if you were to drop both objects side-by-side and at the same time, they would strike the ground at the same time, as the earth would be accelerated toward both objects equally. Thus even if you define "falling rate" as "time until the ground is hit", your statement is still only correct some of the time.
The enemies of Democracy are
I can't remember all the people who were involved, but Rene Blondlot claimed to have found a phenenomenon which he called N-rays. But there was a lot of difficulty in reproducing the experiments elsewhere. An American scientist Robert Wood travelled to France to see the apparatus of the team who claimed the discovery.
The experiment took place in a darkened room and a trained observer called out the readinings he saw. Unfortunately, our scientist hero had removed a metal prism which was said to be a critical part of the apparatus. Under their theory, they should not have detected the readings that the observer "saw".
This experiment demonstrates that science is done by *disproving* things as much as it is my *proving* things.
I have discovered a truly marvelous sig, unfortunately the sig limit is too small to contain i
Deriving the speed of light from batteries and magnets, thereby also proving that the speed of light is independent of your frame of reference!
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
If you place a piece of paper in between the wires (UNPLUG FIRST!), it will ignite dramatically too. Here is a text file with instructions and ascii art. Here's a cooler html file with a decent picture. Here's a site devoted to one guy's JL, and it has some cool gifs and a movie or two (both c. 700kB)- these are kind of disappointing though - the arc is whiter and kind of pathetically small.
What happens is that the air is broken down TO PLASMA between the wires so that it conducts electricity, just like lightning 8-D. The spark then convects upwards due to the very hot air. After it's shot off, air is broken down at the bottom again, and another spark is started.
The best photos are probably HERE, but they're yellow sparks (i think that's to do with the gas) which isn't in my opinion as cool as brilliant blue ones :). TechTV also has a page on it and a cool-ish video if you can view asx files. Their JL is pretty weak though, because it stops before the spark "falls off" the end - meaning the wires are too far apart for the voltage to be that small to be able to turn the air in between into plasma.
Although Eratosthenes was a true genius the world hails Christopher Columbus as a hero even though his accomplishment was sheer accident. What does this tell you about how the world views science and scientists?
More correctly, educated people knew in CC's time that the world was round. Columbus merely managed to come up with a smaller diameter than most people believed which made his trip practical. He was dead wrong and the prevailing view, based on E's calculation, was much more correct.
I have discovered a truly marvelous sig, unfortunately the sig limit is too small to contain i
Umm ... sorta. The feather and the bowling ball experience identical forces, and thus acquire the same velocity in a given time. However, as you say, we assume M_2 = 0 for the *other* force equation, the gravitational force of the feather/bowling ball acting on the earth.
So if we put the M_2 term back in, we find that the bowling ball and the earth meet slightly sooner than for the feather, because the earth is more strongly attracted to the bowling ball. But obviously, this is a *very* small effect.
At least, I think that's what you were getting at. I'm not sure what the moon had to do with it.
Quantum mechanics: the dreams that stuff is made of.
Erastothenes comfortably sat in Greece with a stick and theorized (correctly) about the nature of the world.
Columbus ponied up his own ass and sailed over a horizon where, to the best of his knowledge, nobody'd ever been. He risked himself to experience that world.
Ya can see the same difference today between astronomers and astronauts.
Without astronomers, there would be no astronauts!
"And like that
Ingredients:
Kevin Fox
Take a large class of students, and ask them to come up with any two whole numbers. The probability that any two numbers are relatively prime is related to pi. So you work out the proportion p of people with relatively prime numbers, and then pi = sqrt( 6/p ), IIRC.
Not terribly accurate, but experimental mathematics is very interesting.
dominionrd.blogspot.com - Restaurants on
OK, there, I've mentioned it.
OK,
- B
http://www.bradheintz.com/
- updated
to me the most beautiful experiment is this except replace the lead with two boobies flip-flopping in the wind while the owner of the said boobies is enjoying a vigorous bout of volleyball or something
and not vector format (so no direction is taken
into account).
the vector format:
F=G*m1*m2*r/||r||^3
if you don't care about the direction of the
force and just the magnitude, the radius vector
turns into a scalar and cancels one of the radii
in the denomenator.
IANAL, but I play one on
No. They can be completely self-consistent. The problem is that any mathematical system depends on axioms that cannot be proven within the system. However, to use mathematics as a descriptive language does not require that the axioms be proven; they merely need to be definable in mathematical language.
With the simple neologism "wavicle", you can talk about them in English, too. The problem is that wave-particle duality is contrary to our normal experience, so anybody who doesn't deal with it regularly has a hard time undestanding it. But it's the same problem as teaching musical composition to someone who has never heard music.
You can play a piece for them, and you can describe melodies and harmonies very precisely in terms of mathematical ratios. But the student isn't going to really understand what musical composition is about until you continually expose them to music for a long period of time.
Ingredients:
-One box
-One cyanide pill
-CowboyNeal
-One quantum particle (optional)
--Won't that be grand? Computers and the programs will start thinking and the people will stop. - Dr. Walter Gibbs
I would like to take credit for being the idiot who
provided those equations...
I blindly looked at old homeworks and didn't bother
to take into account the context of the equations.
I blame it on the US education system and the fact
that I had to use M$ on my hw assignments (-;
IANAL, but I play one on
Even more ironic: Eratosthenes was hassled by his fellows, nicknamed "Beta" because he wasn't the best at anything. Now we honor Eratosthenes for his prime sieve and for calculating the circumference of the earth, among other things...and we just know his fellows because they were jerks. Pace Larry Niven, sometimes there is justice.
Of course, this was back when we had really cool, interesting, knowledgeable teachers, not just dick-cheese student-copyright infringing bastards like SERGEI HAZANOV (feed on it, spammobile!) that STEAL prototype graphics by a student willing to trade for an administration job. Grrrr. Of course, this is switzerland and i wasn't a citizen and couldn't prove good enough damages to build a case against him.
- Magnus Effect
- Coriolis Effect
I think the Magnus Effect in baseball and the Coriolis Effect on weather are beautiful. Both are relatively easy to demonstrate, understand and have changed the way people enjoy their lives.Yes. I suspect that with a photomultiplier tube, you could do the one photon at a time experiment on a $1,000 budget now.
It is not really a simple experiment but it shows that while information can not go faster the speed of light, a measurement at one site CAN have an "instant effect" at another location.
Very strange stuff, I went to a conference made by Alain Aspect, a French guy who managed to "implement" what was only a "thought experience"..
Really shows the weird nature of our reality..
Turns out, unbeknownst to anyone, that Columbus' ass was saved because there was a land mass closer than halfway.
It's pretty clear that Columbus knew that the Vikings, and possibly others, had journeyed out into the Atlantic, and found a continent on the other side, within reach of an open longboat from Greenland. Columbus also _assumed_ that continent was Asia. From the evidence available at the time, this was less of a leap of faith than believing the old legends in the first place was. Putting those two beliefs together, the world had to be much smaller than Eratosthenes estimate.
I don't know why Columbus never considered the possibility that there was an unknown continent out there, except that he would have had considerable trouble selling the notion that, based only on ancient legends, he wanted to spend most of the king and queen's money to sail out across the apparently endless sea and if the ships and all that investment didn't go down somewhere out there, find a continent inhabited by savages who were tough enough to run the Vikings out and had little or nothing worth stealing.
Spaniards might not have been daunted by tough natives -- in Ferdinand's and Isabella's life time, spaniards had ended 600+ years of Moslem kingdoms in spain, and then defeated the Turks, who had been terrorizing Italy and Eastern Europe for over a century. Compared to Turks, savages without guns or steel weapons weren't much of a threat. But Spanish soldiers were rarely interested in farming, and they expected to get a whole lot more plunder than corn, pemmican, and beads...
I think the mountaintop one is also possible for today's students, what with GPS and all, or even a really good topo map (+/- a few feet gets you close-enough-for-proof-of-concept).
With a topo map, maybe, depending on the quality of the surveys. But GPS depends on the speed of light to work (it uses the delays in radio signals sent out at precise times from satellites, so when you use it to measure your baseline you are relying on someone else's measurement.
OTOH, survey out a long baseline with enough precision (say across Kansas and neighboring flat lands), measure the GPS delays at each end, and you should be able to calculate the speed of light from that.
It's simple to get ball lightning. This will usualy work. Just put a lighted match in your microwave. It will sometimes make nice plasma bursts of white.
But the plasma gets VERY hot, so be sure to put a rock or somthing under it so it does not scorch the bottom of the microwave or anything.
To keep your microwave safe, put a cup of water in the corner while it is in operation. If you have a cup of water in the corner, there should be little chance of damaging your microwave.
Other experiments:
Take a paper clip. Straighten it out and bend it so it is a U, with both ends bent in so they are fairly close. An arc should jump between the ends of the paperclip. This can melt glass.
Stick a screwed-up cd in your microwave. It will look really cool after you nuke it.
One last thing, the plasma emits mucho UV rays. You can get eystrain from doing this for too long. But these experiments just kick ass, however.
If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth.
Preconditions: You're on a plane, and have a drink in a cup that's close to full (about a cm off the top is fine)
Assumptions: the pilot is sane and sober; the plane is a commercial aircraft not designed for stuff like flying sideways
Normal expectation: when the plane banks to one side, the water would spill out of the cup
Observed behaviour: water level will remain parallel to that of the plane, and hence the table that the cup is on, and therefore won't spill.
I noticed this a few years ago, and reasoned thusly: Other than the rudder of the aircraft, the plane has very little lateral resistance. When the plane turns, it banks at an angle to balance out the centripetal forces created by the plane's turning. To the people on the plane (and the beverage), this is simply an increased downward force, but looking out the window, it appears the plane is tilted.
Of course, if the plane runs into turbulence, the drink may spill.
<tim><
proving that not everything goes around the earth.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
John Conway's Game of Life, the most well-known cellular automaton, shows how nonlocal phenomena can be generated from purely local rules.
Since exposed to the science minded through Martin Gardner's column in Scientific American in 1970, Life has introduced many to the study of complex systems, emergence, etc, etc, which I now see as providing a broader context for the physics (and chemistry and biology and collaborative systems) which we find in this world.
For the record, this does not mean that I am convinced that our cosmos is a cellular automaton, but rather that complex systems provide a tool even more powerful than traditional math for modeling, and thus in some ways understanding, our world.
-- Our systemic servants do not good masters make.
It's pretty clear that Columbus knew that the Vikings, and possibly others, had journeyed out into the Atlantic, and found a continent on the other side, within reach of an open longboat from Greenland.
Do you have any evidence to support this? Recall that it's only recently that the Viking's voyages to America became an accepted theory.
Science is prosaic. It's not there to be beautiful.
If you twist it to make it beautiful, you're denigrating its value as science.
Every experiment that falsifies its hypothesis is exactly as beautiful as it needs to be.
--Blair
G * (M + m) / r^2
(M is the mass of the earth, and m is the mass of the object..) You can substitute values to satisfy yourself that the difference is completely negligible for any reasonable value of m, which is why the 'acceleration due to gravity' doesn't change based on mass.
How can we continue to believe in a just universe and freedom to eat crackers if we have no ale?
Sit in a swivel chair and hold a bicycle wheel with the axis vertical and the wheel itself perpendicular to your chest and the wheel spinning. Rotate the axis by 180 deg so that it is still vertical, but with the axis reversed. The chair starts to rotate to conserve angular momentum.
Why I like about this one is that it is quite amazing if you haven't seen it before, but it demonstrates a principle of classical, high school physics.
Sorry, no.
A stream of particles travelling down both arms simultaneously, without being waves, would not create the interference pattern we see.
Same goes for light.
We can say that a probability wave travelled through both slits simultaneously, and collapsed.
Quantum mechanics shows how everything is both a wave and a particle. Light is no exception, it's just at one extreme end of things.
Are you disputing that or something?
But it would have been cool if they hadn't performed as expected. 'Uh Houston we have a problem, are you sure we're coming home?'
Certainly, all objects fall at the same rate at the surface of the earth. The force involved is given by:
But F=ma, so a=F/m. That means that the mass cancels; for instance, for m1, the acceleration due to gravity equals G m2 / r. So, each body's acceleration is independent of its own mass, but is proportional the other object's mass.So, consider the feather and hammer. While the feather accelerates toward Earth at 9.8m/s, the Earth and everything on it accelerates toward the feather at a negligible rate. Same with the hammer. Result: the observed acceleration for both objects is equal.
However, consider our Jupiter-mass bowling ball. While the bowling ball accelerates toward Earth just like everything else at 9.8m/s, the Earth falls toward the bowling ball at about 318 times that rate, for an overall attraction of over 3100m/s!
(Actually, the situation would be quite a bit more complicated than this because of the tremendous tidal forces involved, but you get the idea...)
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
It's unlikely that Columbus specifically knew the saga of Lief Ericson, but there were plenty of things available to indicate there was land within reach. There are maps from before 1492 showing a continent across the Atlantic. There is the legend of St Brendan, among others. And there is evidence that the English were cod-fishing on the Grand Banks a decade earlier. (For one thing, there was no impact on cod prices in England when due to a war Denmark barred the English from the Iceland fisheries.) It would take remarkable navigation for that age to sail around the Grand Banks for weeks and never veer a little west and discover land. Fishermen like to keep the best spots secret, but might have talked to someone who clearly was no competitor...
I just think it a lot more likely that Columbus's research turned up at least one of these possible sources than that he persuaded the quite hard-headed Isabella to finance his expedition based on an unsupported claim that everyone else was wrong about the size of the world...
After the Spaniards had ethnically cleaned Europe of Muslims there was one other place to open a war front. That was India, which was known to be under the control of the Muslims at the time.
The problem with that theory is that the Spanish had to sail only about 10 miles (to Africa) if all they wanted was to fight Muslims. Or a much easier voyage than an Atlantic crossing would bring them to the current center of Muslim temporal power (Istanbul) or to the Holy Land -- except by that time everyone know that attacking the Turks on their own turf was suicidal. So why would they have thought the Mogul (Mongol/Turkish Muslims) rulers of India would be vulnerable to a small company of soldiers staggering off a tiny ship after a voyage of months?
Of course, Marco Polo's tale left reason to hope that the Chinese were still non-Islam and susceptible to conversion. (The Khan then ruling China actually asked for priests, but the papacy was too mired in internal conflicts to respond.) There might also have been some thought that there might be islands and smaller nations that were vulnerable to a military takeover, but I think the ostensible goal -- trade in spices, tea, and silk, bypassing the Turks, etc. -- was really the primary one. Of course, once they figured out that these "Indians" were different, and did not have the desired trade goods, but were getting gold from somewhere and were remarkably inept at warfare, the way to profits became obvious...
My equation is only a simplification if you stop using Newtonian physics. Barring that, it is accurate. The acceleration of an object as a result of gravitational attraction to another object is proportional the mass of the -other- object, and the inverse of the square of the distance, and nothing else. a1 = G * m2 / r^2. This is true, and as accurate as Newton could predict.
I quite clearly said that the earth (the 'other object' in this case) experiences an acceleration of its own dependent on the dropped object. And clearly if the earth accelerates toward the dropped object faster, r decreases faster and thus both a2 and a1 increase faster. I thought this was obvious.
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