andars

Borrowing from an a old comment of mine:

On one hand, on some scales, Newtonian mechanics is correct "enough" to give results that work, and so in that sense it is just incomplete in that its domain is restricted. On the other, relativity and QM change everything. These new theories may reduce to Newtonian mechanics given certain assumptions, but Newtonian physics assumes things about the structure of spacetime that are fundamentally incorrect (e.g. velocity is not additive). In this sense, one can fairly say that Newton's mechanics are not just incomplete or missing some fine details, but wrong.

I think there is more to the foundations than just the best numbers we can come up with for a given experiment. Our numbers for the gravitational constant, for example, are pretty similar (if more precise) to the numbers in 1891, but the setting in which that number is completely changed. There is no aether, no absolute space, velocities don't add (even though it's "mostly" right on most scales we experience and measure, it is false), space and time get mixed up, etc. Those were all pretty foundational ideas just over a hundred years ago.

"Pony up" must mean something different for me than it does for you. I don't know what it means to OP, in my comment I mistakenly assumed my understanding of the phrase was fairly universal.

Realistically, if the government didn't tax and the benefits were available without payment, how many people would voluntarily pay? Many (most?) will accept a free ride when it is available.

The strength of that "unspoken contract" diminishes as you move from personal friend to distant organization.

I agree that this software has value and it would be nice for people to support it monetarily, but it seems unreasonable to get upset when people don't.

But their software is also free as in beer? It seems strange to make something available without payment and then get mad when people don't pay.

I understand the other non-monetary freedoms that the FSF advocates, this is not about those.

Could you clarify what is nonlinear about that system? From your description, it sounds like a high (4+) order (mostly) linear system. The motor probably has nonlinear dynamics, but so does everything and treating it as linear should work ok.

I suspect the difficulties you've experienced stem not from nonlinearity, but from trying to control a system poorly approximated by a second order system with a second order controller. By cascading, both PID controllers effectively "see" a plant that looks more or less second order, so the controllers are much more effective.

Sorry, I'm not qualified to give a good answer.

I would guess that the relatively long wavelength of ultrasound could potentially cause resolution issues.

I'm not very familiar with the plasma dots approach, but from a cursory look it appears that it is not capable of RGB. On the other hand, there is nothing that can fall out of confinement so the display is probably more stable.

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?

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.

The cellulose comes from the black liquor on a spoon (see 0:46 in the video). The put the spoon at the focus of the laser and with luck some particles get confined. After the trap is lost, the particle just sort of drifts away in the air, since they are only tens of microns.

Nonetheless, everybody calls the displays in Star Wars "holograms". Smalley notes this, and the title is using the word in this colloquial sense. There is an unfortunate disconnect between the technical and colloquial meanings of "hologram".

I've seen this in operation and am acquainted with the researchers. I may be able to attempt to answer some questions about it.

Or he plans on growth in other segments (solar, batteries, ?)

> Tesla rockets

Tesla is distinct from SpaceX.

Jobs had a $1 salary and no bonuses. That doesn't say anything about stock options, grants, etc. It sounds like Musk will get minimum wage and no stock anything if Tesla doesn't meet the thresholds.

Tesla, the car company, probably will never come close to the market caps thrown around in the article.

Tesla, the energy company, might.

My understanding:

GPUs are (generally) in-order within each thread, but they are pipelined. The pipeline is filled with instructions that are ready to execute from across many threads. If all threads have an unmet dependency (previous instruction or memory access), the pipeline will stall.

The Power Wheels don't put the motors in parallel or series, it switches the two 6V batteries between parallel or series. The motors are always in parallel.

See the patent: https://patents.google.com/patent/US4639646A/en?assignee=%22...

What kind of electric motors? Brushed DC by chance?

Would you mind sharing your field of study?

It isn't self-tuning, and it doesn't "learn."

From the paper: "The three constants c_i need to be set by the implementor"

Under "Future Directions": "One obvious thing to do with this system is to have it learn and tune its parameters with experience." The work presented in the paper does not do this.

"This network was designed in an ad-hoc, if traditional, way. First, a human tried to control the bicycle with the simulator. After many attempts, the human finally became a somewhat skilled operator of the bicycle ... the human at this point was able to describe the key parameters which were being attended to, and based on this, the two-neuron network was designed." By "designed," the author means "the three constants were selected."

This sounds like the "arbitrarily complex procedure" you are looking for.

It looks more like a cascade of a P controller (theta setpoint to gamma setpoint) with a PD controller (gamma setpoint to torque). But yeah, basically just classical control.

Excluding the coast and the east bay, it is not really a concern. A tsunami would have to come through the golden gate channel and make a quick turn to get to Mountain View with any strength.

The inundation map for Mountain view is here: http://www.conservation.ca.gov/cgs/geologic_hazards/Tsunami/...

And here is one for the entire bay area: http://www.conservation.ca.gov/cgs/geologic_hazards/Tsunami/...

The remainder of the inundation maps can be found here: http://www.conservation.ca.gov/cgs/geologic_hazards/Tsunami/....

Here is an animated simulation of a tsunami hitting the bay area: https://www.youtube.com/watch?v=bP_AIWgknfI

This seems potentially backwards to me. If we apply a voltage source across the terminals, parallel coils between the terminals would result in higher voltage across each coil than would series coils. With series coils, the total voltage applied would be divided between the coils.

Could someone clarify?

I understand that it's a stretch; thus the "in some sense" and "close".

See my last sentence. It's not clear to me how you could reformulate analysis, which in many ways is the study of the infinite, into discrete maths in any way other than the very loose sense of starting with ZFC.

Yes. Here is a paper from some Japanese researchers in 2015: http://www.hapis.k.u-tokyo.ac.jp/public/hiroyuki_shinoda/res...

In some sense, don't the modern formulations of real analysis, etc. already start from as close to discrete maths as you can get (set theory)?

Sets -> Naturals -> Rationals -> Reals

I don't understand how you could reformulate study of continuous structures into discrete math in any sense other than the above.

I'm pretty sure they recently restructured by creating Rocket Lab US and making the existing Rocket Lab NZ a subsidiary to get more flexibility regarding some arms restrictions.

Last I heard, you had big claims and have yet to test your ideas in physical hardware. People will probably be less likely to ignore you if you have something that you can demonstrate being able to manufacture reliably and that you aren't just exploiting some simulation artifact.

More about it: http://www.aaronsw.com/weblog/000432

No, it's like saying the only compiler for x86 is created by Intel (paid for by the sale of processors) and they therefore don't have an incentive to make the compiler particularly good at optimizing. If it does a better job at optimizing, people can get away with cheaper processors.

I'm not saying there is any intentional area bloating going on, just that there is little incentive to make Vivado better at optimizing.

Read https://www.bunniestudios.com/blog/?p=5018 to see where I'm coming from.

EDIT: It makes a lot of sense in my head, but perhaps I'm overlooking something important. I'd be interested to read in more detail why it doesn't make sense to you.