I lived in Cape Canaveral during the shuttle program and have witnessed all but 5 launches live, once from within the 5 mile zone. The sound at that distance is very loud but, also different compared to a 15 mile distance away. The sound is very sharp and "cracks" unmuffled by air until it gets further away. You can feel the sound waves in your body. It is pretty emotional, even if you've been waiting for hours for liftoff and then the launch gets scrubbed.

I was in Georgia when Challenger exploded. I watched it live on TV and for a short while I couldn't understand why the launch looked so different on TV. It really took a few a seconds to realize what was happening. I cried that day.

Today i learned the water used during a launch is used to dampen sound waves.

Counter-rotating propellers sparked my curiosity when I first saw them on a British Seafire Mk46 at a flight show in the early nineties.

So my amateur's answer would be that it's about the problem of turning the engine's power into thrust. With increasing power, you can either increase the propeller's RPM or its area. So you either a) spin it faster, b) increase its diameter, c) use a more favourable blade geometry, d) add more blades.

a) and b) both lead to blade tips moving faster, and once they approach the speed of sound, wave drag sets in and ruins your day. b) also runs into issues in terms of ground clearance. Thus the Kim Jong-un blades on planes like the An-70: short and fat.

c) is rather difficult to do in terms of manufacture -- that's why more pronounced blade shapes are a relatively recent development.

d) on a single propeller decreases the efficiency of each blade as it passes through the previous blade's vortex. That's why, for instance, German planes in WW2 almost exclusively relied on 3-bladed propellers with increasing blade size, whereas Supermarine went to four and even 5 blades rather quickly. You can work the issue to a certain degree by modifying the blade geometry, thus the 8 blade props on a modern A400M.

Adding more blades by adding another propeller gets around d), although the aft prop still loses efficiency compared to the front prop. On the other hand, counter-rotating props massively reduces problems with torque, which can be rather horrendous for single engine prop planes. The Bf 109, for instance, is (in)famous for being difficult during take-off as it pulls to the side quite violently.

#1 bluetooth uses a slight offshoot of mpeg2 audio compression which gets worse because you are most likely recompressing something already compressed with mpeg and that makes things even worse. This is the strength of AptX, it is an audio compression designed to not get exponentially worse when dealing with mpeg compressed audio. THAT SAID! Anyone know what phone he is using? The GOLD phantom supports AptX, so if he uses a samsung/htc/lg phone he would have been using AptX.

#2 speaker construction, it is an overblown Flip3 with radiators on the side. The radiators are designed to capture the back pressure of speakers and convert it into more audible sound waves, very good at saving the low frequencies and directing them back at the listener. The problem is it is a secondary uncontrolled speaker. This means your sound balance can go out of wack. Perfect for a $79 portable speaker, not ideal for a $3000 home theater setup. Also the speaker appears to be..mono? so you need 2 of them for stereo?

Yea, sorry, you can buy speakers that are not much bigger than this, hell you can buy a SET of front facing speakers and a good sub for $3000 and do better.

Who fights for the unborn? Not the left.

I do agree that these new hindrances are fairly messed up but that is what is available to lawmakers.

There should be a few instances that abortion is allowed and these should be done at the hospital at same day surgery clinics where minor procedures are preformed.

AS fat as the 13 yr old she is not being punished. Where are the cops arresting the rapist? PPH are obligated to report that.
The baby’s heart will start beating during the fifth week. The heart is too small to generate enough sound waves to be audible, even when amplified by the use of medical equipment in your doctor's office. However by the 6th week the beats can be measured.


Its odd if I kill a pregnant woman I get charged with 2 counts of murder. If the woman kills the fetus no problem with that.

Whenever there's a mosquito vectored disease, people talk about eradicating mosquitos, but never consider their role in the food chain, and it is not a small role.
They also never consider the effects of the eradication methods, which are often poison sprayed into the air or onto ponds. Decades ago, a 12 year old boy designed and made a device for eradicating mosquitos in water using sound waves for a science project, and it worked. He tuned his device to resonate at the same frequency as the gas bladder in mosquito larva, popping it and killing the mosquitos without effecting anything else, and leaving no residue. For some reason, I never hear about that method being used, but instead often see people dosing small ponds with poison, oil, or bacteria, all of which harm other organisms.
Targeting single strains of mosquito with genetics may be a good way to deal with disease issues, but will certainly also have unexpected unpredictable consequences. I hope they remember the fiasco caused by creating killer bees and study the issue from all sides thoroughly before releasing them into the wild.

Why have they bothered lying about this? I don't get it.

Obviously fake, as was pointed out, you have to breath helium for it to change your voice It's a function of sound waves traveling through a different gas density, the same reason your voice goes lower when breathing nitrous oxide. The gas doesn't change your vocal chords as some people seem to think.

Your video, Engineering students use sound waves to put out fires, has made it into the Top 15 New Videos listing. Congratulations on your achievement. For your contribution you have been awarded 1 Power Point.

so minimally that far... this was pretty good from wiki:

Shock waves form when the speed of a fluid changes by more than the speed of sound.[3] At the region where this occurs sound waves travelling against the flow reach a point where they cannot travel any further upstream and the pressure progressively builds in that region, and a high pressure shock wave rapidly forms.

Shock waves are not conventional sound waves; a shock wave takes the form of a very sharp change in the gas properties on the order of a few mean free paths (roughly micrometers at atmospheric conditions) in thickness. Shock waves in air are heard as a loud "crack" or "snap" noise. Over longer distances a shock wave can change from a nonlinear wave into a linear wave, degenerating into a conventional sound wave as it heats the air and loses energy. The sound wave is heard as the familiar "thud" or "thump" of a sonic boom, commonly created by the supersonic flight of aircraft.

YES I agree 120% about the FPS and FOV limiting in games. WHY oh WHY do they take away or limit those options with such a heavy hand? Whenever I complain about it everyone acts like I'm insane to care about that because you can't see it.

I draw an analogy to a vinyl vs a digital recording, I may not be able to hear the different frequencies produced by the vinyl, but I can feel the difference in the sound. It's because complicated changes (rapidly drumming is most apparent) are based on an approximation of the sound wave in a digital recording (depending on the quality of the recording). Vinyl, meanwhile, is a recording of the actual sound wave grooved into the plastic.

Although it's nearly impossible to hear that difference, people still buy vinyls for some reason. Back to fps and fov though, I may not be able to see higher than 30 fps, but I don't live life (or drive cars) at 30 fps like a flip book. Your eyes don't give you an accurate picture of the world, they only give you a useful one.

Real life runs @ ∞ fps and htz. I'm not asking for anything close to that, just make the choice available or don't ban me for hacking when I go into my config file and try to change my fov and fps limit manually.

"Yes but it gives those players who change those settings an advantage"

.
.
.

Fuck you.

My justification is simply that it has a good track record. If you are really trying to say that I am unreasonable to assume that all physical laws will remain more or less unchanged for the next five seconds then you demonstrate your own stupidity.

The main problem with your justification is that it is logically fallacious. You're still using circular reasoning. Your evidence that the future will be like the past is the past. Is it correct reasoning to use logical fallacies?

You haven't demonstrated that we need to know anything with absolute certainty. Is there any practical value to it?

Can you show me one instance where knowing that something has been the case in every conceivable instance since the dawn of time is just too vague for you?

Things seem to hum along just fine under the crazy assumption that breathing in and out is the way to go.

Well, the thing is, we live in a world of certainty, not uncertainty. What this means is that you are living a double life of sorts. You are uncertain about everything in theory, but of course you never live that way in practice; you expect everything to continue as it has from the beginning of the Creation. You expect that when you jump up you will come back down again. You expect when you say the words "juniper tree" that the sound waves will carry those words to the other persons ear, and they, using universal rules of logic, will comprehend what you're talking about. You are living according to the ideals of a Christian worldview, but simultaneously denying it with your atheism.

Did you know, for instance, that the idea in science of nature being lawfully ordered is a Christian one? It was supposed by 12 century Christians who believed that the Universe was governed by Gods laws, and that we could suss out these universal laws by investigating secondary causes. Here is some of the history of all of that:

http://bede.org.uk/sciencehistory.htm#introduction

So this world of certainty we live in is based in no small way off of Christian ideals and principles. You could not actually justify any of it unless you invoke an omnipotent God who created and maintains all of these things, and will continue to do so. So, the argument is the impossibility of the contrary, which is not only a denial of the world of certainty that we live in, but also the loss of any basis for rational thought.

Tags for this video have been changed from 'salt, shapes, imogen, voice' to 'salt, shapes, imogen heap, voice, sound, waves' - edited by calvados

"QM is no more difficult to understand than relativity"

I've always found some of the "weirdness" of quantum theory to be a little easier to wrap my peabrain around than some of the weirdness of relativity.

Honestly - consider the Doppler effect. With sound waves (and every other wave except for light/EM, so far as I know), the frequency of the wave changes depending on the relative velocity of the observer to the wave. But with light, we can observe the Doppler effect while the relative velocity is constant (speed of light remains constant regardless of the observer's frame of reference). WTF?

it's almost as if they believe that the sound waves coming through the microphone is enough to drive out illness... er, I mean "satan."

If religion is a matter of faith and spirit, what's with all the shaking and shouting?

And actually this is in 3 dimensions as sound waves travel from its source (your speakers) to your ears in a spherical manner...like boobs growing bigger and hitting you in the ear holes>> ^bamdrew:

however the setup was audio in a 1-dimensional space, to which I cry NAY! ... also color,... lets call that a sub-spatial dimension... 3.5 dimensions! you monsters.
>> ^Quboid:
>> ^bamdrew:
you fools! ... the audio is another dimension! as is the time across which this video occurs!
you've created another 3D transformers movie... God help us...

Audio's not a dimension, it exists as waves within our 4 dimensional space/time. But the time in this a 2nd dimension, which means this is 2D and therefore have more depth than the actual movies ... (or, I don't know, some other lazy "omg the movies suckzz lol!" type joke, I'm tired).