Wikipedia:Reference desk/Archives/Science/2021 April 24

= April 24 =

SpaceX launch Friday and space junk
After the SpaceX launch with a crew Friday morning, they were warned about a possible impact with space debris. It missed by 28 miles. Can't they use Newton's Laws to calculate it better than that? Bubba73 You talkin' to me? 04:47, 24 April 2021 (UTC)


 * For calculating the trajectory of an object in free fall using the laws of physics, one needs initial conditions, specifically position and velocity at some moment of time. These do not follow from any laws; one has to obtain the data through measurement. Any measurement has limited accuracy and precision, introducing some uncertainty in the projection. Think of the initial position as not being a sharp dot but a fuzzy one. Proceeding with the calculation (essentially solving a differential equation by numerical integration), the uncertainty increases along the trajectory: the fuzzy dot becomes a fuzzy cloud. --Lambiam 08:16, 24 April 2021 (UTC)

Could an analog of this 3d effect used with photographs, be used to try to make people visualize 4 dimension?
Could an analog of this 3d effect used with photographs, be used to try to make people visualize 4 dimension?

There is this image (https://www.adorama.com/alc/wp-content/uploads/alc_images/article11780_1.jpg), its made of real life photographs, a photograph is 2d, but it keep changing between photographs of the same scene photographed from the same position at first and second dimension but a different position at third dimension, if you change between images really fast (so change the third dimension really fast) it looks like you are seeing a 3d thing, but its just 2d images one after another being shown.

Could a 3d program use the same effect (changing the 4th dimension position really fast) to try to make people see 4d? Would this trick work with 4d?2804:7F2:59B:D224:3D6C:F80E:E544:D94F (talk) 14:28, 24 April 2021 (UTC)


 * 3D models shown on a flat (2D) screen could use this effect (parallax) to convey some 3D information in the same way as the image you linked to. To extend that to 4D images you'd need a 3D viewer, but flicking between two different 3D viewpoints might not help to convey 4D information, since our visual system interprets changes in parallax as depth cues, so it would probably just look like shaking. Also, 3D viewers such as virtual-reality headsets can be quite nauseating if the viewpoint changes independently of the person moving, so it's probably not a good idea. nagualdesign 15:01, 24 April 2021 (UTC)


 * By the way, Charles Howard Hinton spent years of his life working on purely mental techniques for visualizing the fourth dimension, and he and a few of his followers claimed some degree of success... AnonMoos (talk) 15:59, 24 April 2021 (UTC)


 * Most anything by Muybridge works. For that matter, any sequence of photos works. Assuming the fourth dimension is time. ←Baseball Bugs What's up, Doc? carrots→ 16:07, 24 April 2021 (UTC)


 * Humans and many other animals are able to maintain a mental 3D model of the outside world. An interesting question is whether this is an innate specialized 3D ability that has been wired by evolution into the neuronal network of our brains, or is acquired by our experience of moving around in a real word in which only three dimensions are available to us. --Lambiam 17:27, 24 April 2021 (UTC)


 * You can get kind of the same effect as that picture by looking through a View-Master and alternating closing your left and right eyes. ←Baseball Bugs What's up, Doc? carrots→ 18:04, 24 April 2021 (UTC)