You can't prove the existence of another observer, adhering strictly to logic. You can choose to acknowledge them as observers, but you can't prove it (Descartes). Your senses can (and presumably have, if you dream or see an optical illusion ever) been deceived.

I'll second that.
I built a nearly identical plane 25 years ago, it cost about $125, and another $200 for the controller setup. It's wings were made of fiberglass/graphite spars inside dense foam cores...easy to build, easy to repair, and didn't hurt if it hit a person. (it did only have about a 15 min flight time without thermals, but batteries and motors are better now) Why are they going with carbon fiber for a non-combat fixed wing drone over fiberglass and/or foam (or are they testing combat drones)? Is it just to make it cost more? Why not just CNC mill them out of titanium billets? ;-)

$50K? Something smells here. Should be under $1K unless there's a lot we aren't seeing. Maybe it's all in the electronics and optics (it would need a bit more than a cell phone camera), but it still seems exorbitant. I think it could be more efficient to make them cheap and disposable/recyclable rather than 'hardened'.

Can anyone explain what's happening at about 1:20, where you can see a faint image of the rocket, it's trail, and then what looks like a clear image of the inside of the rocket nozzles WAY back (and farther apart than they really are)? At first I thought this might just be a focal point of the exhaust, but it's not just a point of light. Is this some known optical effect, or is something else going on here?

The video I remember from a few years back showed optical effects from several devices and the toilet stood out in my memory because of the sheer range of the air disturbance.

I've looked all over and can't locate the video.

I think it's a bad example, since if you put dry ice in water it skitters, splashes, and boils, but pee doesn't do that. (At least mine doesn't) But good try finding the Schlieren Optics one.

Your video, What Does Sound Look Like?-Schlieren Optics, has made it into the Top 15 New Videos listing. Congratulations on your achievement. For your contribution you have been awarded 1 Power Point.

Indeed the lens does seem a bit spendy. For the specifications of the linked setup article, the mirror (31cm Protected Aluminum) runs about $2550 at Edmund Scientific.

Oh lawd... I'm sorry to add another unrelated comment to this video, but this is pretentiousness taken to extremes! I think you mean beyond you. Defeat conceded, good argument @enoch.

On the matter of trolls - there really isn't a troll problem here. You tell me a website with the same number of members and traffic of here that is as civil and well presented as this. We don't even have a massive amount of bad language.. As Sir Meatius of Loafendale said in 1754, on the subject of light and optics, "Objects perceived in the rearward looking reflecting devices may appear to have their sizes increased proportional to their actual location." (Chiroptera Ex Infernus) What he was trying to say is if you've been bugged by someone unfairly recently, it's a big problem to you.

Also, although i saw a lot about siftquisitions, i never really understood them, or had them presented to me in the way of "Hey, come help us decide how the sift will be," kind of thing. So i always avoided it and I may even have been young and annoying 5 years ago, and avoided it to keep my cover. But i'd love to be involved in things like that now, i am part of the community but it's more because i like talking to people. Some of the people i know over the years have given me videos to sift so that i'd keep minimum necessary status, and i got my avatar given to me by someone who made me feel very welcome for my comment contributions. I think any chance for the community to help itself is a good thing, it might get noticed if it's presented that way. And as someone else said, we have changed a lot in 5 years, and i don't just mean the sexy UI. Tell me if there's a poll!

Your video, Power of Optics ..., has made it into the Top 15 New Videos listing. Congratulations on your achievement. For your contribution you have been awarded 1 Power Point.

EMPIRE maybe they can get some ridiculously high bandwidth link up and going wirelessly?

OK... well at least have it use a single dinky fiber optic cable to do it.

Hey, as long as the resolution and frame rate is there, I dont care if they pull their displays out of old Tempest arcade machines.

Just to play devils advocate....

a ground based optical telescope? Really?

Surely no matter how good your optics, you will still suffer from atmospheric interference. Wouldn't we be better off with another hubble?

That didn't look like a stinger to me but it's hind leg. I think it was just an optical accident. It would be interesting to find out from the guy videoing what happened to the spider.

*ban

Sorry but you cant post your own yt videos on this site. As per posting guidelines.
http://videosift.com/faq#posting_guidelines
which you were warned about when you posted this video.

self link
http://videosift.com/video/Reversing-Arrow-Optical-Illusion#comment-1751383

The rotors can't be that slow moving right? Optical illusion with filming speed?

Wow! You knew about high speed fiber optic trading in the 70's? Can I borrow your time machine?