5 ms·

I'm not sure if your question is rhetorical (‘please, do it’) or not (‘is is possible?’) but, yes, it should be possible to find lower bounds of such events, by

by bertil 13y ago

I'm not sure if your question is rhetorical (‘please, do it’) or not (‘is is possible?’) but, yes, it should be possible to find lower bounds of such events, by multiplying: - estimates of meteroid paths (per year); tenths of thousands; - estimates of people sky-diving (per year); 3 millions; Source: http://www.statisticbrain.com/skydiving-statistics/ http://www.statisticbrain.com/skydiving-statistics/ - time of one jump; minutes, say two; - time of one meteroid drop; minutes, say two; - length in meters of a typical jump; 3,000; - length in meters of a drop; 20,000; - and the square of an estimate of visibility boxes — say meters across —; 1000 m^3; divided by: - a year; 525,948 minutes; - Earth’s jumpable atmosphere (that's the whole thing) squared: 3×10^24 m^3 (Wolfram Alpha). My take is that the over-all volume of atmosphere and that meteroids can drop at anytime makes it extremely unlikely: an order of 10^-35 with my very rough estimates. 10^30 years of jumping would not make it likely. Even by estimating millions of asteroids shattering in millions of pieces, that even should be rarissime even considering the length of human species’ history. More parameters, such as the fact that people tend to jump when there is daylight or pay attention to the landscape, certainly counts. If you compare to how many cameras are in the ground, we should have seen a meteoroid last meters much sooner. So, if statistical disappointing skepticism is to be considered, what makes all those camera unlikely candidate appears that they are too stable and generally face other cameras and the ground were the stone might be recovered. It doesn’t make that video fake; it’s just that, using a Bayesian framework, it comes off as incredibly unlikely not to have been done using editing. It makes it all the more spectacular if it were. I’m guessing the camera makers can easily tell that from the recording on the device. Please — correct my math, reasoning or any assumption: I certainly got most of it wrong.

jamesaguilar 13y ago
1000 cubic meters. A box ten meters on each side? It seemed like the meteorite was further away than that in the images. I don't disagree with your conclusion, just this step.
- bertil 13y ago
  I had the feeling it zoomed closer at one point, meters. My idea was that you needed the meteoroid to be at least that close to notice it — it certainly depends the size of the stone. Considering a bubble with a 200 m radius (3×10^7 m^3) doesn’t really change the conclusion: at the current jumping rhythm, it’s still unlikely that it might happen any point throughout the human history.
  - hrkristian 13y ago
    Statistics are bordering on pointless in establishing the validity of the video and claim. We know, full well and without any calculation the chances of such a shot are infinitely small, given that, the only reasonable action is ignoring it for the sake of tangible evidence. For example, the skydiver was in a wingsuit, and the rock flies past him just as his parachute had opened. This means another person would have needed incredible timing to be able to match a rock throw/drop; having it go past him at a recordable distance while not hitting him. I'm a skydiver so I've had my share of scares connected to parachute deployment, hanging around above something is for example a huge no. As the parachute opens, it's practically dead in the air; widening in area rapidly. Were someone to hang above him he is putting himself in real danger, his wingsuit is susceptible to changing winds and a few hundred meters (a reasonable estimate for how far you can expect a human to be able to aim a falling rock near another skydiver) go by in a flash. There is also the practicality of holding onto a rock in a wingsuit (which you'd need to be able to follow his trajectory in the air). He could have devised a contraption on his stomach for the rock, and pulled it out at a proper distance, but a wingsuit diver pulls in with both arms in a quick motion in order to pull his 'chute, and would have to do the same for the rock, or suffer a nasty spin at a time he needs full control... But reaching in still causes a dive, and loss of control, he loses forward momentum and falls rapidly, and he has to pull out a few pounds of rock in sync with the free hand in order to maintain direction, and now, in the midst of all this he has to be sure his rock does not hit his friends parachute and rip a hole, at an altitude I would be uncomfortable deploying my emergency 'chute, if he even notices the nasty tear in time! There are actually more points to be made, but all in all, the film may have been doctored, but the jump itself most certainly was not an elaborate hoax.
    - 13y ago
marshray 13y ago
Perhaps a simpler path is in the relationship of the number of people who have been verifiably struck by meteorites (e.g., https://en.wikipedia.org/wiki/Ann_Hodges https://en.wikipedia.org/wiki/Ann_Hodges ), the proportion of people on the ground to those skydiving with helmetcams at any given time, and the relative cross-sectional target area of a person compared to the visibility frustrum of a helmetcam.
- bertil 13y ago
  Indeed. Most jumpers now have several cameras so you can assume the proportion of skydivers is enough. It‘s still less than ten millions minutes overall, while billions of humans live half a million minutes each year. Now considering three recorded events (listed in your source) over the course of five centuries… This still means it would take billions of years of jumping to reasonably come across such an event. That calculations makes it far more likely that the previous one I made, most likely because I highly underestimated the number of meteoroids. The weakness of that method is that you are limiting the visibility of humans on the ground to being struck, although one can argue that the buy in Uganda was a case of it coming close enough to notice.
  - marshray 13y ago
    Unless there's something special about low altitude, why wouldn't we expect a terrestrial camera with a view of the sky to have a reasonable chance of capturing dark flight? I know skydivers do a lot of filming, but seems more likely that the first dark flight would be caught by tourists on a sunny day or something.
aaron695 13y ago
Lets say all 3 million jump at once and jump for a hour and can fully see 100m at 360 degrees. (Earth is 510072000km2) =3000000 * 3.14 * 100*100/1000000/510072000 = 0.0001846798 They only cover .01846798 percent of the Earth. so you'd need 10,000 visible meteorites per hour for this to happen once per year. So it seems unlikely. The fact they both got footage of it is obviously correlated but I also think it drops the probability a bit. But things like that they are skydiving are not relevant. It's be equally amazing if they filmed it from a building or just looking up in the sky or from a plane. This is the tricky bit I'll just hand wave over. This might override the overestimates above. Complicated, but looking at the figures and the fact they both got good footage I'd tend towards fake. I'd be very interested to see a proper write up on this.
stcredzero 13y ago
I'm not sure if your question is rhetorical With me, you can assume it's meant in the spirit of "can you give three examples?"

by bertil 13y ago

jamesaguilar 13y ago

1000 cubic meters. A box ten meters on each side? It seemed like the meteorite was further away than that in the images. I don't disagree with your conclusion, just this step.

bertil 13y ago
I had the feeling it zoomed closer at one point, meters. My idea was that you needed the meteoroid to be at least that close to notice it — it certainly depends the size of the stone. Considering a bubble with a 200 m radius (3×10^7 m^3) doesn’t really change the conclusion: at the current jumping rhythm, it’s still unlikely that it might happen any point throughout the human history.
- hrkristian 13y ago
  Statistics are bordering on pointless in establishing the validity of the video and claim. We know, full well and without any calculation the chances of such a shot are infinitely small, given that, the only reasonable action is ignoring it for the sake of tangible evidence. For example, the skydiver was in a wingsuit, and the rock flies past him just as his parachute had opened. This means another person would have needed incredible timing to be able to match a rock throw/drop; having it go past him at a recordable distance while not hitting him. I'm a skydiver so I've had my share of scares connected to parachute deployment, hanging around above something is for example a huge no. As the parachute opens, it's practically dead in the air; widening in area rapidly. Were someone to hang above him he is putting himself in real danger, his wingsuit is susceptible to changing winds and a few hundred meters (a reasonable estimate for how far you can expect a human to be able to aim a falling rock near another skydiver) go by in a flash. There is also the practicality of holding onto a rock in a wingsuit (which you'd need to be able to follow his trajectory in the air). He could have devised a contraption on his stomach for the rock, and pulled it out at a proper distance, but a wingsuit diver pulls in with both arms in a quick motion in order to pull his 'chute, and would have to do the same for the rock, or suffer a nasty spin at a time he needs full control... But reaching in still causes a dive, and loss of control, he loses forward momentum and falls rapidly, and he has to pull out a few pounds of rock in sync with the free hand in order to maintain direction, and now, in the midst of all this he has to be sure his rock does not hit his friends parachute and rip a hole, at an altitude I would be uncomfortable deploying my emergency 'chute, if he even notices the nasty tear in time! There are actually more points to be made, but all in all, the film may have been doctored, but the jump itself most certainly was not an elaborate hoax.
  - 13y ago

marshray 13y ago

Perhaps a simpler path is in the relationship of the number of people who have been verifiably struck by meteorites (e.g., https://en.wikipedia.org/wiki/Ann_Hodges https://en.wikipedia.org/wiki/Ann_Hodges ), the proportion of people on the ground to those skydiving with helmetcams at any given time, and the relative cross-sectional target area of a person compared to the visibility frustrum of a helmetcam.

bertil 13y ago
Indeed. Most jumpers now have several cameras so you can assume the proportion of skydivers is enough. It‘s still less than ten millions minutes overall, while billions of humans live half a million minutes each year. Now considering three recorded events (listed in your source) over the course of five centuries… This still means it would take billions of years of jumping to reasonably come across such an event. That calculations makes it far more likely that the previous one I made, most likely because I highly underestimated the number of meteoroids. The weakness of that method is that you are limiting the visibility of humans on the ground to being struck, although one can argue that the buy in Uganda was a case of it coming close enough to notice.
- marshray 13y ago
  Unless there's something special about low altitude, why wouldn't we expect a terrestrial camera with a view of the sky to have a reasonable chance of capturing dark flight? I know skydivers do a lot of filming, but seems more likely that the first dark flight would be caught by tourists on a sunny day or something.

aaron695 13y ago

Lets say all 3 million jump at once and jump for a hour and can fully see 100m at 360 degrees. (Earth is 510072000km2) =3000000 * 3.14 * 100*100/1000000/510072000 = 0.0001846798 They only cover .01846798 percent of the Earth. so you'd need 10,000 visible meteorites per hour for this to happen once per year. So it seems unlikely. The fact they both got footage of it is obviously correlated but I also think it drops the probability a bit. But things like that they are skydiving are not relevant. It's be equally amazing if they filmed it from a building or just looking up in the sky or from a plane. This is the tricky bit I'll just hand wave over. This might override the overestimates above. Complicated, but looking at the figures and the fact they both got good footage I'd tend towards fake. I'd be very interested to see a proper write up on this.

stcredzero 13y ago

I'm not sure if your question is rhetorical With me, you can assume it's meant in the spirit of "can you give three examples?"