I would guess that the relatively long wavelength of ultrasound could potentially cause resolution issues.
(Thanks @iliis for posting about this research)
That page says the femtosecond plasma display is pretty safe. This display was - and I believe still is, though I could be wrong - using a UV laser for confinement, which is sorta scary.
Can you levitate multiple particles at the same time? How fast are they moving? How sensitivie is it to disturbances in the air?
Yes, but their device currently is only capable of levitating a single particle. With the current approach, the device would need one laser for confining each particle. The lasers used for RGB could potentially be multiplexed between particles, but this is less likely to work for the confinement due to the instability of the trap.
> How fast are they moving?
Pretty slow. All the "big" images (Leia, grad student, etc) are long-exposure. You can see the particle moving in real-time at about 0:50. In the videos, you can see the device can almost do real-time persistence of vision for volumes substantially smaller than a fingertip.
> How sensitive is it to disturbances in the air?
As I mentioned above, the confinement is weak and the trap is pretty unstable. Its possible that they have improved the longevity of the trap in the last few months, but when doing long-exposure the device is surrounded by a heavy cloth barrier to block both external light and air movement.
What kind of safety equipment is required to view it?
Pick any two of those aforementioned groups, and you'll find plenty of members from one who consider the other's members to have unfathomably bad reasoning and common-sense skills. And yet, somehow, some members of all those groups bear wonderful intellectual fruit.
Or another way to look at it, we could reduce almost all questions, in science or religion, to something like "what is the nature of this stuff around me?"
A subpart, "how can I interact with the stuff?" A subpart of that question, in turn, is "what are the consequences of those interactions?"
Sometimes the stuff around you is carbon. You can burn it or build things with it. If you breathe enough of it in certain forms, you might suffocate.
Sometimes the stuff around you is other people. You can help them or hurt them in a near endless variety of ways. The consequences are complex but it's generally better to not be a dick, for a variety of reasons.
Maybe the stuff around you is... all of reality? Which may or may not be controlled by a unimaginably powerful law giver. Maybe not, but if so, that would certainly affect the consequences of a lot of actions, so it would be worth trying to work out how that system worked if that was the deal.
To be clear, I'm not arguing for Pascal's wager here, I'm just needling the idea of non overlapping magisteria.
Isn't it all just, "How does reality work?"
I haven't been a Muslim or a Buddhist, but I was a Mormon missionary who taught Buddhists of many sects, plus South American Catholics, European atheists, Muslims, Raelians, and your odd Yakuza while I lived in Japan.
I was taught to respect these people for what they had already learned and experienced, and to teach them a simple, elegant model of my belief system. In studying that model I realized that I hold and have the responsibility to shape, apply, and evaluate multiple models of my religion through my own life experience. This becomes an ever-evolving science that is in principle one and the same with the more technological science posted here. There are deeper qualitative questions and experiential aspects and anecdotes that are really more like fractals than questions, open to broad and deep exploration. But those elegant models, the simple ones--right in there you have a huge amount of religious people who really don't differ much from your complete-opposite anecdotal scientist in the important ways.
I could go right now and google reasons why Mormons and science don't mix, or I could go out and find a Mormon who would argue with most any scientist (come to think of it, my Mom is a good one!), but the boundaries there are in the end just different from my own and I find there's absolutely room for that. I hold my own models lightly, and compare them with others' from time to time. But--and I doubt I'm some freak religious exception here--nobody is dictating my models and their composition / combination to me. I act in many ways in respect to my church like a robot (Sunday? Church!), not because I have to, but because in my mind, the overall experiment is yielding good results and I'll change variables as I need to when I examine them. I got the feeling that others in other religions act and feel basically the same way. As I mold my models I think of myself as a type of scientist, and hope any scientist would consider the study of religion from a scientific view (model all the time, measure what you can) as an absolute (and hopefully enjoyable) mandate.
The wonderful intellectual fruit you speak of is something I experienced first hand when I was a BYU student. As a teenager I was told how wrong evolution was by my dad (an extremely educated man himself with multiple degrees), heard how certain it was from my sunday school teacher (a respected surgeon), and then I went off to my BYU biology class and was immediately taught about talk.origins and told "hey if you guys (freshmen) don't believe in evolution that's fine, but at least educate yourself". This was a huge faith-strengthener to me; a diversity of models is not only OK but developing one's own educated models was seen as wisdom in a nutshell.
I'm not sure how you'd get that from my original comment. But rereading it today, I realize I wasn't very clear. I apologise for that. Let me restate it more explicitly:
1. To be done well, science and engineering require careful thought and, to a certain extent, sound reasoning.
2. Some people holding world view "A" consider the holding of world view "B" to be intellectually indefensible, for many values of "A" and "B".
3. And yet we have plenty of empirical evidence that good science and engineering work is being done across all of those world-view-holding groups.
As far as why this particular article made me thing of this issue, it's because Mormons are sometimes ridiculed in (at least) U.S. popular culture for holding an intellectually indefensible world view. E.g., [0].
Edit: This is funny, no one was a sense of humor. Just imagine Donald Trump's holographic head spinning slowly while he gives the state of the union. That's the future.
https://news.ycombinator.com/newsguidelines.html
Edit: you've posted a ton of unsubstantive comments and we've asked you before to stop, so would you please stop? We're hoping for higher discussion quality here.
Perhaps (I disagree, but its subjective), but also ungrammatical and substance free. The latter is probably what HN doesn't like.
This isn't Slashdot, and +1 Funny isn't, in general, a thing.
Depending on when they managed to trap two particles, we can start applying Moore's law and double it every so often.
Actual title: "Better than a hologram: BYU study produces 3D images that float in 'thin air'"
Article text: "First things, first, Smalley says. The image of Princess Leia is not what people think it is: It’s not a hologram."
Can we not editorialize and/or get the titles completely wrong?
hol·o·gram noun A three-dimensional image formed by the interference of light beams from a laser or other coherent light source.
I have never seen a hologram that is also a volumetric display. To me, this would be the holy grail of hologramming, since you could use interference for occlusion effects.
Honestly I feel like the best solution is just to train everyone critical thinking skills but I guess in practice that doesn’t seem to happen.
If you're looking for the bleeding edge of what's here now, RED[1] the camera company is putting out a hologram cell phone probably like next month I guess with a hologram display from a company literally called leia[2].
[1]https://www.theverge.com/circuitbreaker/2017/9/8/16272838/re...
I think having a controllable particle is a nice-feat but probably is overkill for 3D displays, you only need to know where the particles are so you can use them as a screen.
Although the 2010 paper project on layers of waterfalls, it's easy to imagine a 2d water droplet grid where you watch the droplets form and drop with a hi-speed camera and with a video projector you then project the right pixel at the right time so that light ray intersect water droplet. You can even try this today at home with a shower jet and a pico projector, and see beautiful clouds of red green blue rays.
It's probably a fun engineering project to get the right combination of liquid properties, size of droplets, frequencies, video bandwidth to obtain stunning results.
If the PCMR folks already hate everyone saying the human eye sees at 25FPS, imagine how they'd react to that!
But I think they might have been talking about how long the trail would persist for in our vision, making it appear as one object when it goes in circles. Not how quickly you can flash images in front of us before we won't be able to see them. I'm not sure if it's true in that case.
Oh well.
47+ points
Actual title of this submit was "Better than a hologram: BYU study produces 3D images that float in 'thin air'"
Love.
