Domain: amasci.com
Stories and comments across the archive that link to amasci.com.
Comments · 237
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Re:Flying through its own downwash = bad.
If a symmetrical object is moved through the air, there will be equal displacement on each side, and no lift will be generated. A wing is asymmetric, the air traveling underneath experiences little disturbance, the air displaced around the top becomes more spread out, spreading out a gas decreases the temperature and pressure, the differential pressure between lesser displaced air beneath the wing and the more displaced air above the wing generates lift. Again, the air beneath the wing tries to fill the void created above the wing.
Please explain how a plane flies upside down, then. They can do so for extended periods of time.
You might want to look at http://amasci.com/wing/airfoil.html/ for a hint.
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Re:Running Outfrom http://amasci.com/weird/end.html:
"When I began my physical studies [in Munich in 1874] and sought advice from my venerable teacher Philipp von Jolly... he portrayed to me physics as a highly developed, almost fully matured science... Possibly in one or another nook there would perhaps be a dust particle or a small bubble to be examined and classified, but the system as a whole stood there fairly secured, and theoretical physics approached visibly that degree of perfection which, for example, geometry has had already for centuries." - from a 1924 lecture by Max Planck (Sci. Am, Feb 1996 p.10)
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Re:From what I understand...
All you need is an appropriate length of oxygen free copper cable/wire with sufficient shielding and appropriate gauge. All but the lowest of low end OEM cables meet these needs. Beyond this, there is zero difference in cables other than packaging and branding. Any perceived difference is in the listeners head.
Close but a few facts are left out. Lets touch base on speaker cable and what it needs to do. It needs to move electric power from one place to another. Along the way it needs to keep most of the power (all cable has resistance and loss even superconductors which have a bit less). In moving power is should deliver all frequencies the same.
Now back to your statement... oxygen free copper cable/wire Hmm, the first step seems to trend to snake oil. I'll grant you that oxygen free has lower resistance than plain copper, but how much? Is it worth the money? Would the money be better spent on maybe a larger wire size? You will find the lack of copper wire resistance tables for copper wire and oxygen free copper wire almost completely absent. The reason is because the change is almost not measurable. If it essentially makes no change, why spend the money.
Copper wire facts are easy to find and are well docummented.
http://www.otherpower.com/cgi-bin/webbbs/webbbs_config.pl?noframes;read=6346
http://www.stealth316.com/2-wire-resistance.htm
http://www.epanorama.net/documents/wiring/wire_resistance.html
http://amasci.com/tesla/wire1.txt
http://www.thelenchannel.com/1wire.php
On the other hand the data on oxygen free seems to be tied up in perceptions and not solid facts. Where are the tables?
http://www.freepatentsonline.com/20060198757.html
http://mobile-emotions.com/speakerwire_faq.html?1062644160781
http://www.roger-russell.com/wire.htm
http://www.patentstorm.us/patents/5443665-description.html
http://www.cda.org.uk/megab2/elecapps/pub122/sec72.htm
"Oddly enough, it isn't the freedom of oxygen in copper wire that makes any difference. The process of removing oxygen also removes the impurity of iron and it's this impurity that can cause the resistance to be slightly higher."
Could someone please define and give a measurement to me for Slightly higher? As in is the change enough to spend money on? Until someone publishes a table, I would assume slightly higher is slightly less than the measuring test equipment. A larger wire size is a measurable change. Oxygen free as far as I am concerned is below the threshold of measurement.
Beyond this, there is zero difference in cables other than packaging and branding.
OK here I disagree with you again. The number of strands and twist in the wire affect the ability of a wire to withstand repeated flexing. When I worked doing some TV studio stuff, I had to show some of the features of some of the cable to the staff. The low loss and low price was a draw to the PHB who thought he was a studio engineer. I showed him the flaw in his reasoning when I held up a 3 foot piece of coax and pushed out a ceiling tile. Then I held up a 1 foot length of super flex which had much poorer response and the 1 foot length flopped over like a piece of braided nylon rope. The signal loss for the studio was a trade off for cable that stood up well following the cameras without breaking. A cable that lays flat instead -
Other molecules?
I have some questions. Maybe somebody with a 20KV power supply and rubber boots could find this out..
1. Would work with other polar solutions? Of course you want one that won't combust..
2. It seems this must be in operation at small scales, where static electricity easily makes huge charges? link
3. If you took 2 icicles and made a V out of them could you make a Jacob's Ladder high voltage traveling arc with them? (maybe the tips would shoot off into someone's eye so we should use ice blocks tilted away from each other) Would the arc melt the ice where it touches, melting just enough ice into water to maintain an arc? Maybe it could be started by wetting the blocks or painting a line of iron filings or silver paint on each side?
4. This sounds like it might have some parallels with the cellular structures formed by convection and magnetic fields in the sun?
5. What can be done with this at a household scale with just static no scary generators? It would seem a 0.5mm gap is within body voltage range, or 2-3mm with clothing static. (see above link). I was wondering if water could be made to climb up a stepped (or spirally lined) bowl, or wander across a stroked fresnel lens. Though I guess a web-like cloth thing would be more of a gap.. -
Re:Assumptions are bad, uncheckable assumptions wo
> Reality is all about the physical state of being
Time is not real? So time is physical? Show me this "thing" called "time".
Are your dreams real? If they are not real, then how did you experience them?
Is consciousness physical? (Having interacted with non-human consciousness, that is a clear no.)
Reality is so much MORE then just the physical, which is the point you completely missed.
> see science as a rival church.
Science sets _itself_ up as a Rival Church; by ignoring the wisdom of the past Religions it has very much become its _own_ Religion.
Science through Quantum Mechanics have discovered most of these:
Awareness - There is no reality until one observes it.
Balance - Everything has an opposite, which brings equilibrium.
Eternity - Now is eternity, since "not Now" doesn't exist.
Faith - The Subjective Experience leads to the Objective Truth, and that it will lead to a more correct understanding of Reality when it has no proof of this.
Holiness - Honesty in searching for Truth which it
Infinity - There are many infinite parallel universes / dimensions.
Oneness - Everything is connected. i.e. Energy is mass, E=mc2
Uncorrupted Religion teaches the same thing at its core, when people aren't busy trying to convert everyone else to their incomplete religion.
I'm not the only one who sees the close minded nature of Science.
* http://amasci.com/weird/wclose.html
Others have written about the problems of Rationalism
* http://michaelprescott.freeservers.com/skeptic.htm
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You are a Spiritual being in a Physical body having a Human Experience. -
Re:*cough* below the speed limit?
Congratulations. You're part of the problem.
People driving more slowly, but less aggressively will have a higher traffic throughput than people trying to drive more quickly and aggressively in high traffic density situations.
People in Portland drive a little quicker on the freeways but keep at or under the speed limit on surface streets -- unlike Atlanta where it's whatever you can get away with. It takes some getting used to, and it's very frustrating when you're in a hurry and already worked up, but it's pretty comfortable if you're in a more chill mood. The homogeneity of speed also means less people getting frustrated at not being able to travel how fast they want to, and it provides less opportunities for rear-end collisions.
San Diego's a lot like Atlanta from what I hear. I'd seriously recommend living a month in a community with less aggressive traffic and trying to adapt to it. It'll give you a whole different perspective on what traffic is supposed to be like, especially if you take to heart the link I provided above. -
Re:Where to Begin With the Problems?
What then is the reaction to the lifting force? Remember all forces require an equal and opposite reaction - Newtons laws still apply at this scale.
The lift (due to pressure differences etc) needs a reaction force (required by Newton). You can't have one without the other. You can calculate the lift of a wing using lift coefficients, air density, velocity etc and lo and behold that force will be balanced by the mass x acceleration of the downward airflow. You can't have one without the other - the lift has to "push" against something.
You can't claim that significant amounts of air aren't directed downwards behind wings. Have you seen wingtip vortices in cloud? Could a helicopter hover without a downdraft? The wingtips vortices have an overall downward movement - planes can't fly without them.
http://www.av8n.com/irro/profilo1_e.html
http://www.av8n.com/how/htm/airfoils.html#sec-circ ulation-vortices
http://amasci.com/wing/whyhard.html
http://www.diam.unige.it/~irro/gallery.html
There is no one single effect that causes a wing to produce lift - it is a combination of interrelated effects:
http://www.av8n.com/how/htm/airfoils.html#sec-cons istent -
Re:Now..
First of all, as an Oregon resident, I think you guys do good work, mostly; thanks.
Another idea I've heard of for solving the traffic jam problem is, rather than minimum speed limits, just have a variable maximum speed limit. Basically, replace all the signs that say "55" with electronic signs that would say "55" most of the time, but if there's an accident, you lower the limit a few miles before the accident, say to 50 then 45 then 40. So by the time you get there, everybody is already going slower anyway, and traffic can flow smoothly (at a slower speed) instead of everybody bunching up and trying to change lanes. Obviously the difficulty here is the cost of replacing all the signs.
Are you familiar with this page?
By the way, what's your opinion of increasing the speed limit on I-205 from 55 to 65? Traffic permitting, the left lane usually averages 65 normally anyway, and it doesn't appear to be a problem. Do you believe there would be significantly more accidents if the limit were increased? -
Re:but...
Microwaves most certainly can cause ionization. Want to create plasma in your microwave? The easiest way I know is to cut a grape nearly in half, leaving only a thin ribbon of skin connecting the two sides. Fire it up, and watch the arc. For more dangerous microwave experiments, check this page out.
In a more general sense, microwave creation of plasma is even used in a number of industrial processes. Example: gas deposition of diamonds. You have a chamber that's mostly hydrogen with a little bit of methane. The microwaves split the methane and ionize the carbon and hydrogen. The carbon deposits and can form either diamond or graphite. The hydrogen ions preferentially attack the graphite, so overall, only diamond tends to build up.
A search for "microwave ionization" yields 11,300 hits. Don't put it in quotes, and you get almost a million. "Microwave Ionization of Na Rydberg Levels", "Microwave Ionization of H Atoms", "Microwave Ionization of Highly Excited Hydrogen Atoms", "Microwave ionization of hydrogenlike Li and Na atoms", "Microwave ionization of sodium with subnanosecond 8-GHz pulses", and so on. -
Re:Well, admittedly, the image is interesting...
And you're an imbecile. Water is slightly blue, though of course it's not noticeable in a small glass. A simple google search would have cleared that up for you, but feel free to spread the bullshit. http://amasci.com/miscon/miscon4.html#watclr
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Umm... TROLL??? I'm right!!!
Why was I modded troll?!? Water DOES indeed have a slight blue tint to it. Oceans are blue even on cloudy days because the sky has little to do with the fact that water is already blue. For those who still hold to the misconception: fix your brain.
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Interesting
Apparently if the transmitter/receiver are smaller than the wavelength used to transmit the energy, and they are located within ~1/4 wave of each other these efficient inductive energy transfers are possible. They are using the 'near-field' effects of EM radiation, not the more commonly used far-field. See: "Energy sucking antennas": http://amasci.com/tesla/tesceive.html " The "energy grabbing" effect is very limited. It's a nearfield effect. It could only operate within about a 1/6- or 1/4-wavelength radius around a coil or capacitor antenna, or in the region between the peaks of a propagating EM wave. In other words, when we add a tuned circuit, we can increase the "effective size" of a tiny antenna until it resembles a half-wave dipole antenna. It usually would be easier to simply build a half-wave dipole in the first place. Normally we would do so. "
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About the heat-sound-work continuum
There's been this interesting article about the spectrum of "work", including both heat and sound:
So... Heat is a form of sound?!
Or should I say "heat" is sound, since many educators believe that the word "heat" causes misconceptions. I'll say it this way: thermal energy within physical objects is actually a very loud screech of hypersonic whitenoise. When a hot object is touched to a cold one, "phonons" of sound start pouring between them.
http://amasci.com/miscon/a-rant.html
The upshot: "heat
energy" is the regime where sound has become so high in frequency that it
moves slowly and is renamed as "thermal vibrations."
http://amasci.com/heat.txt -
About the heat-sound-work continuum
There's been this interesting article about the spectrum of "work", including both heat and sound:
So... Heat is a form of sound?!
Or should I say "heat" is sound, since many educators believe that the word "heat" causes misconceptions. I'll say it this way: thermal energy within physical objects is actually a very loud screech of hypersonic whitenoise. When a hot object is touched to a cold one, "phonons" of sound start pouring between them.
http://amasci.com/miscon/a-rant.html
The upshot: "heat
energy" is the regime where sound has become so high in frequency that it
moves slowly and is renamed as "thermal vibrations."
http://amasci.com/heat.txt -
Re:Why so much Hummer Hatred?
Then don't follow so close. 99.999% of rear ending accidents are caused by following too close. It's also bad for congestion. see: http://amasci.com/amateur/traffic/trafexp.htm
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Re:You can do it without sensors, too.
the flashing of which screws up traffic behind them, because people think there's a problem
Traffic Waves is a neat explanation for this phenomenon. It's a fairly lengthy article though. -
TRAFFIC WAVES s/b required reading for all drivers
The famous "Traffic Waves" essay:
http://www.amasci.com/amateur/traffic/traffic1.htm l -
Re:NO, you can't just do this now.The longer you take to move up, the more traffic backs up at the back, and the more people who obstructed who are trying to get on/off the road. But at least you save 5 cents on your petrol bill... Come on, think about the engineering here; which is more efficient: turbulent or laminar flow?
The standard reference for this take on the topic is here: http://amasci.com/amateur/traffic/trafexp.html -
Re:Bugger off
http://amasci.com/miscon/miscon.html
Just google "textbook errors" and you'll find more examples than you ever wanted. -
Re:Of Course They ShouldI'm pretty sure I found at least one mistake in every science text book I used at school. You mean like this?
http://amasci.com/miscon/miscon.html
And this?
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Don't block - teach skepticism
No - they shouldn't block Wikipedia.
Instead students should be taught critical thinking skills and how to be skeptical of any information.
Textbooks are full of errors (see http://amasci.com/miscon/miscon.html, http://www.textbookreviews.org/index.html?content= http%3A//www.textbookreviews.org/California_announ cement.html%3Fshownews and http://school.familyeducation.com/education-and-st ate/history/38673.html or do you believe that Daniel Boone was in the Continental Congress and that Sputnik was a nuclear warhead?)
Wikipedia can be an excellent source of information. It is typically much more current than other sources and had great introductory articles on many technical subjects. The links it has can often lead to further research. The page history can provide insight into underlying controversy.
Clearly, Wikipedia is not perfect: it can be gamed, like Stephen's Colbert's drive to increase the number of elephants in Africa; is subject to fanatic bias; and what's the popular conception isn't necessarily the truth.
Instead students should learn to question everything, parse the logical structures, and not rely on single source for information. In this way Wikipedia can be an excellent teaching tool. -
Braking on tailgaters is really just a bad idea.
Not only is that reckless, unsafe, and (where I live, at least) like to enrage the person behind so that they begin deliberately stalking you, but it's also the kind of idiocy that can cause pileup accidents and traffic jams. I used to do this all the time before I sat down and really thought about the ramifications of my actions.
Here, read the article that changes the way I drive. Mysterious "no accident" traffic jams are caused by the amplification of sudden slowing by a line of cars braking from a single event. The guy behind the guy behind the guy you're pulling this stunt on has to make a more sudden stop than the guy you were targetting. This sort of effect can amplify itself throughout dense traffic and eventually spread out to cause stop-and-go traffic. It's a very inconsiderate thing to do when you consider the effects of "winning" your little game against the effects it can have on everyone else.
That said, if you must try to push back at those trying to push you around on the road, it's much simpler, less accident prone, and less likely to shock traffic into a jam to just let your foot off the gas and gradually slow down. I haven't found any tailgater that's willing to stick behind a guy that's slowed to 10 MPH slower than they were going when the tailgater first got impatient enough to hang on my bumper.
Really, though, the best approach is to just avoid the fast lanes and go at a more relaxed pace. Pushing back at bullying drivers only works you up into a rage and makes you a less safe driver. Trust me, I find myself less miserable when driving now that I don't drive so competitively anymore, so do it for yourself if not for others. -
Re:Not necessarily in order...
I used to check out http://freshmeat.net/ almost daily, but that was when I was only a few years into Linux and still on an endless search for software that did different things, and at the time it seemed simpler to just wait and see what came up on fm every day (you could easily tell how active things were that way, too). Speaking of fm---does anyone have a copy of that old butchered-meat logo fm used to have, waaaay back, before the beginning of the fm II theme?
About weekly, I'll check out http://amasci.com/ (amateur science and electricity stuff), http://en.wikipedia.org/ (duh), http://www.cray-cyber.org/ (free supercomputer access), http://www.hpcalc.org/ (HP48/49/etc calculator stuff), etc., to check for new stuff. I'll check my http://facebook.com/ and http://myspace.com/orangesquid (shuddup) messages about weekly. From time to time I might browse http://www.amazing1.com/ (catalog which has Tesla coils and stuff, though they're not actually the best place for parts/kits/devices) or search for scientific equipment or old unix systems on http://www.ebay.com/ (see the Used SGI Buying Guide FAQ, etc).
I also check up on some of my friends via http://os.livejournal.com/friends every few days.
Lately I've been choosing a new section on http://scitoys.com/ to read every few days. Every few weeks, I'll usually find a different information-type site to read through gradually, or pick a topic to research on wikipedia. -
Re:Human tetrochromats do not see UV
More importantly, they can't see in IR. To me, having heat vision would be way cooler.
Actually even "normal" people can see in IR, albeit only somewhat utsidr thw "visibile" part of the spectrum. However The eyes are not very sensitive to this region, so heat vision is out of the question.I first found out about this when looking straight down the beam of a Class I (ultra low output) Laser with a wavelength of 832-852 nm. This is the laser found in my laser mouse. When I look directly down the beam I see a red dot. (Well sort of like a dot. A bit blurry, but I would expect that.
More interesting is this site: http://amasci.com/amateur/irgoggl.html
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Re:Outlet wired wrong?
Maybe the power supply was wired wrong, even
/with/ a polarized cord?
[See http://amasci.com/amateur/whygnd.html%5D -
Re:Experiment!
One of the *best* sites out there that I've found for understanding the real mechanisms behind all kinds of electrical phenomena, in addition to telling you how to play with them, is Bill Beaty's Amateur Science pages. He also maintains archives of fringe theories and stuff, too, if you're curious about those sorts of things.
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Re:But is it practical?
Unless there has been a complete repeal of the laws of physics then communication by induction will be subject to the law of inverse squares....you know reduction of power by the square of the distance
Naively, that would seem to be the case, but look to A.C. resonance effects. Then power transmission is much more effective. See http://amasci.com/tesla/tesceive.html. -
Re:Killing the car while diving can be just as bad
In Washington State (US) if you rear-end someone, you will get a 'following to close' ticket. And for good reason... you were! Following too close is also bad for traffic. see anti-traffic: http://amasci.com/amateur/traffic/trafexp.html
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Re:Old, old, incredibly old news
Basically if you read the cure page he advocates doing what Germany has done on their freeways... slow down traffic before it enters a stoppage. The Germans do it via variable speed limits (the autobahn no longer is unlimited speed throughout) that gradually bring down the speed of traffic approaching a blockage, and alert drivers of blockages ahead, so no one, even tailgaters, have to panic stop. They also legislated that during heavy traffic (rush hour) heavy trucks may not pass each other, and are restricted to the right-most lane.
Wonder what it'd be like if their ideas were more broadly adopted -
Re:Density waves?Here's the traffic waves web site that explains it all:
This guy did exactly what you say: tested what effect a single driver could have when trying to calm traffic waves. I've given it a shot on occasion (when traffic was heavy enough to prevent other drivers pulling around me), and it does work to some extent. -
Traffic waves
The subject sounds very much like William Beaty's texts from 1998: Traffic Waves - sometimes one driver can vastly improve traffic, except Beaty's text is way more enlightening...
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Re:On a very busy road...
Umm. you may want to *read* the article at http://amasci.com/amateur/traffic/traffic1.html (posted earlier). His evidence suggests that it *is* helped by people letting others in (in an effort to keep traffic flowing) and is actually *hindered* by behaviour such as yours.
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How to resorb a traffic jam
This informal study has a nice description of how a single good driver can actual reverse the trend by single-handedly "breaking the soliton".
In other words, if you're caught in a traffic jam, let a wide space build in front of you, and try to adopt a constant (slow) speed. While you may not directly benefit from it, the jam will resorb itself for those who follow you.
This page includes simulations in a variety of contexts. While the study is informal, it is still quite convincing from a fluid-dynamics perspective. -
Re:Density waves?
I think you're remembering this guy's website:
http://www.amasci.com/amateur/traffic/traffic1.htm l
If it's not, I think you'll like it anyway. -
Old, old, incredibly old news
See this Science Hobbyist article from January 1998. It's long and detailed, and suggests practical steps individual drivers can take for breaking up (or causing!) traffic jams. Yes, dear readers, this is a nine-year-old dupe.
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Re:On a very busy road...
It would help to cut down on the standing waves if people applied the 'join slowly, leave quickly' rule. If you see a queue ahead then slow down to give it time to move before you get there, then as soon as the road is clear accelerate away (to a safe speed). I see waves like this every day and see many people rush to join it so they have to slam on the brakes. When I get out the other side people are leaving huge gaps that slow down the escape of others.
There's an old article on this, with animations, here.
Try and be part of the solution. -
Forget about the Google...
Am I alone for thinking that 15 months in prison, three years of probation, and $20k in restitution is just a LITTLE high for MAC spoofing to score some free wifi? Even if it was taken to the level of interfering with the signal, 2.4G is unlicensed. As any aspiring hacker should know, a properly configured microwave will cause wifi (and 2.4G phones and baby monitors) many problems. Unless he was pulling some seriously bad juju, this is Mitnick-esque "damages".
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Here's the actual paper. This could be real.Here's the paper, or at least the abstract. The talk was given yesterday at the American Institute of Physics in San Francisco. Here's the abstract, but it doesn't tell you much.
In our work, we investigate whether, and to what extent, the unique physical phenomenon of long lifetime resonant electro-magnetic states can, with long-tailed bona-fide (non-radiative) modes, be used for efficient energy transfer. Intuitively, if both the drain and the source are resonant states of the same frequency with long lifetimes, they should be able to exchange energy very efficiently, while interaction with other environmental off-resonant objects could be negligible. Of course, intricacies of the real world make this simple picture significantly more complex. Nevertheless, via detailed theoretical, and numerical analyses of typical real-world model-situations and realistic material parameters, we establish that such a non-radiative scheme could indeed be practical for middle-range wireless energy transfer (i.e. within a room, or a factory pavilion). Important novel applications are thus enabled.
The author is credible; he has a good track record in non-linear optics.
There's a somewhat nutty exposition of this resonance phenomenon here by a radio ham. There's actually some decent physics in that article, if you ignore the nutty stuff. This phenomenon has been known for decades. There's a way to actively drive an antenna into resonance and increase the amount of power it receives. The problem is that if you have those resonant currents flowing in your antenna, most of the energy gets lost in resistive heating as the currents slosh around in the antenna. This idea might need superconductors to make it work.
This area hasn't been studied much recently because it relates to antenna design for waves much longer than the antenna. All the action is up in the gigahertz range today, where antennas are tiny. Almost nobody's working on better AM broadcast receiver antennas any more. Interestingly, those wierd ferrite-rod antennas that are inside AM broadcast radios use this phenomenon. There's a radio ham in Finland who built an active resonant ferrite rod antenna for 3 to 12MHz AM signals.
Right now, this power transmission scheme is just a theoretical concept. The physicist talking about it hasn't built one. So it's not yet clear if it can be realized. But it's standard EM physics.
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Classical quantum absorption
> It isn't so neat for amplitude and phase. Firstly, they are not conjugate variables
> (like position and momentum), so measurement of one does not imply the other is disturbed.
How do you measure phase without disturbing amplitude? Amplitude would be an energy measurement while phase would be a time-domain measurement. Time and energy are conjugate variables. I admit that the limitation on measurement of phase and amplitude is not as clear to me, but it seems like another facet of the same.
> Unfortunately this does not correspond to duplicating the photon. Consider the
> photoelectric effect. http://en.wikipedia.org/wiki/Photoelectric_effect This is
> a good rugged experimental demonstration that light interacts in the discret
> lumps we call photons;
I understand you to be making an argument here that photons can not be copied by the splitter because they are discrete entities and each goes either one way or the other. Right?
> If you're able to resolve the double slit experiment and the photoelectric
> effect without invoking superpositions, I'd be very interested to hear.
I'm glad you asked. The photoelectric effect demonstrates that the light absorption interaction is quantized, and I certainly agree with that. The point to be made here is that this quantization does not have to be explained by quantizing the photon; it can be equally well explained by quantizing the absorption. The result is equivalent, since both cases result in a quantum of light being absorbed. The reality is not equivalent, since aside from the photoelectric effect I have not seen any experiment giving evidence that photons are such particles.
My alternative explanation is that light is continuous in energy and no such thing as a "photon" exists. Atomic absorption is quantized because of discrete energy levels available to the electron. Atomic energy levels are discrete because the electron forms a standing wave around the nucleus and those waves are only stable at specific integer frequencies.
The process of absorption occurs as follows. The electron orbit by itself (orbital size of ~0.1nm) is too small a target to absorb a light wavelength (400-700nm), for the same reason that you need a long antenna to listen to the radio. A frequency of 100MHz has wavelength of 3m and can not be heard if your antenna is only a millimeter in size, which is the same proportion as between light and electrons. The electron orbit, being an oscillating wave, generates and electromagnetic near-field (which does not radiate, but rather acts like energy storage) which couples to the incoming light wave and starts "sucking" energy out of it if the light wave can resonate with the near field. See this newsgroup thread and this article with some specific calculations.
When the light frequency is resonant with the electron frequency the nearfield "antenna" gains energy, increases in amplitude, and proceeds to suck in even more energy as the effective receiver size increases. During this process the electron is in an unstable orbit, where the standing wave doesn't exactly "line up" and so keeps going up to and falling back from it, resulting in an equilibrium of energy transfer between the nearfield and the electron. You might thin -
Re:Title is pretty circular
Close. Just remember that scientific theories and laws differ intrinsically. A theory doesn't become a law after enough time or validation.
Myth 1: Hypotheses Become Theories Which Become Laws -
Re:Accelerometer
Note that this will drain your battery life in this configuration.
Convert the bicycle into a generator.
http://www.amasci.com/amateur/coilgen.html
http://computer.howstuffworks.com/question658.htm -
Traffic Waves
From: http://www.amasci.com/amateur/traffic/traffic1.htm l
"Have you ever been driving on an interstate highway when traffic suddenly slows to a crawl? You inch along for many minutes while waiting to see the accident which must have caused the jam. At the same time you also curse the "rubberneckers" who are causing the whole problem. But then all the cars ahead of you take off at high speed. The jam is over, but no accident, no police cars, nothing. WHAT THE HECK WAS THAT?!! A traffic jam with no cause? In the rear-view mirror you see all the poor saps behind you still stuck in the jam. But why? If all those people could just speed up at the same time, the whole traffic jam would evaporate. Why don't they ever do that? What caused the mysterious slowdown in the first place?" -
On the (kinda) same topicThere is a site on traffic waves by a physicist who has observed and experimented with the patterns that naturally occur in traffic.
He believes that by changing our behavior on the road, each one of us has the potential to seriously affect traffic waves.
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My two $ 0.02
So, I live in Slovenia (I doubt any of you know where that is). But we have a nuclear plant. And it's been running for quite a while now. Because I've also studied physics I've found out, during some lectures, that the measurments taken around the nuclear plant show, that the grass around it recieves the exact same amount of the yearly dosage of radiation as something located far far away. Therefore, this energy is very clean, much cleaner than cole.
Right, so, then a disaster happens. Well, chances are very slim for a disaster. Today, we have a higher safety regulation for operating of nuclear power plants, and we are not competing on who gets to restart the turbines faster (check this) without using safety measures.
Besides disaster possibility, the problem is also waste dispossal as a poster pointed out before me. Where to put it. You simply cannot dissolve the waste, or this is to expensive. And I don't think the problem with space dumping is the image of Columbia blowing up. Waste baskets can be made that whitstand such blasts. It's more of the awarness that we can't already pollute the space, since we fuc*** up mother Earth. And it's becoming an increasing security concern too with all the terrorists roaming around. Imagine a break-in into the waste storage facility. It's easy to make a dirty bomb. Breaking into the plant itself is much harder, although it's still a possibility.
In conclusion, I think we have to accept the risks of possible danger (we fly with airlens, but those also crash don't they?) if in turn, we get back a possibility for a cleaner environment. And until we develop things than can use all the free enegry just lying around and as long as we use things that rely on our supply of power (computers among other things :-) ), we'll have to face it that we live in a world we created. Maybe we should build reactors underground, or in a separate nation somewhere in the middle of nowhere... It's all a possibility. Anything is better than coal. -
A few random thoughts.
Sounds like fun. (As an aside, I'm shocked by the number of people arguing against having after hours fun with such toys. Is the slashdot readership really so cowardly and unimaginative? Sure, one has to be careful and should avoid pissing off the bosses during the first few weeks at work. And it goes without saying that if the electron microscope happens to break while you're using it for personal projects, bad things are likely to happen to you, unless you have or happen to be a particularly cool boss. But, the risk may well be worth it.)
If you've got access to a scanning electron microscope, any sample should be fun. Around here (a multi-group academic facility) the machine is jealously guarded by a dedicated staff person and we get charged rather a lot of money for each use, so I haven't done any recreational microscopy. But, just looking at the stuff we're supposed to look at is overwhelmingly nifty. (Obviously you should stop and think before putting foreign objects into either the miscroscope itself or a sputtering chamber.)
With die cutting, ceramics, and electroplating, you could certainly make some beautiful cases for homebrew projects. If you go in for a retro look, try to cook up some faux-bakelite. (Or real bakelite, for that matter, if you can get your hands on the stuff.)
Another possibility would be tinkering with electrostatic levitation. Suspended objects are always neat.
You've also got the ingredients for making homebrew optics toys. With lapping and plating gear, you might be able to make your own optical quality mirrors for homebrew telescope parts / lasers / holography setups / etc. Anything else involving precision ground metal parts and custom ceramics is an obvious candidate: home made particle detectors / geiger muller tubes, for example.
And there's always the obvious option of making really big capacitors, charging them to really high voltages, and zapping things. (As described, for example, here http://www.amasci.com/amateur/capexpt.html ) -
Real Scientific Applications...
This could mean a great deal for real scientific applications such as the "aura detector" http://www.amasci.com/freenrg/aura/aura.html
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Re:microwaves more than 100% efficient?
Microwaves are perfect for this since they hit the resonance frequency of water
Actually that's not true: see for example
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Re:microwaves more than 100% efficient?
Microwaves are perfect for this since they hit the resonance frequency of water
Actually that's not true: see for example
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Re:I understand the first two...
Actually I don't think you even need the bumper sticker. IIRC in PA (and probably other states), if you rear end someone you're at fault, unless you can manage to prove that the other car cut you off. You are responsible for keeping a safe distance between you and the car in front of you.
As far as I know, this is correct.
I've heard of people turning on their headlights (which also lights up the taillights) to scare the person behind them by making them think they're seeing brake lights, without actually slowing down. Personally I always drive with my headlights on, because it makes me more visible to other drivers (even during the day in good weather), and my brake lights are very sensitive (they come on as soon as my foot touches the brake pedal).
However, when someone is following you that closely, the best thing you can do (assuming you're not already in the rightmost lane) is to maintain speed, turn on your right turn signal, wait for a safe opportunity to do so, and change lanes. Remember, it's not a race; you don't get a prize for crossing the finish line before the other guy. Other drivers are idiots - let them be idiots, and stay out of their way.
Cool insightful geeky traffic stuff here -
mad scientist props
There are all kinds of electric devices you can make that look like they are straight out of an old horror movie. Jacob's ladders are quite simple to build. You can find all the parts on ebay. If you are more ambitious, you might want to try a tesla coil.