"They may not be able to illiterate why "
"They may not be able to illiterate why "
We had a high resolution, full-body scanner at work that was being used to build a database of body shapes. I volunteered but was rather dismayed when I loaded the 3-d model to see what shape I really am
Two dollars is a lot - paperbacks I bought in the late 1970's were under a dollar so your theory about an inflated price does look plausible.
One more thought before I go off to sleep
The spacecraft is the source of the magnetic field so that means the field lines have to terminate on it. Which means hot plasma is continuously blasting into you.
The paper is a one pager of introductory plasma physics. It isn't a serious calculation and it wasn't meant to be. Anyway
Their model is as follows. A plasma will reflect all electromagnetic radiation below a certain frequency, determined by its density. The plasma exerts a pressure like a gas and they then assume confinement of the plasma with a magnetic field, balancing the plasma pressure with the 'pressure' that a magnetic field exerts on charged particles. They then say that we can make magnetic fields in the range up to 100 T and working back, estimate the plasma frequency, which turns out to be in the UV. So great, you can deflect lasers into the UV with a modest confining field.
You need to look at some of the other numbers though.
First, what sort of plasma density do you need to reflect UV ? The answer is something like 10^28 per cubic m. This is enormous - fusion plasmas are about a million times less dense). It's getting close to solid state density eg if a solid has atoms 0.2 nm apart this is 10^29 atoms per cubic m. That is not going to be easy
The other thing to look at is the required plasma temperature. They assume a temperature of 1000 K, Unfortunately, the density of a plasma at 1000 K at thermal equilibrium is extremely low unless the background pressure is huge. So it has to be a lot hotter, in particular, comparable with the ionization energy which is roughly 100 000 K. And really, we need a fully ionized plasma because the magnetic field is not going to confine the neutral gas that we are using to make the plasma so that means we need a 100 000 K plasma. This means that the required magnetic field goes up by a factor of 10.
Would somebody else like to estimate how much power you need to dump into the plasma ?
Typically, there is no single clock that is "the reference". The international time standard, UTC, is an average of about 400 or so atomic clocks from all around the world. There are a number of caesium fountains currently contributing to UTC. Even in a single laboratory, where there a number of clocks, these clocks will usually be averaged and one clock then adjusted to keep to this average. There are various practical reasons for this. If you have a number of similar clocks, the average will have a more stable frequency than a single clock. Some clocks are better at very short averaging times, others better for the long term so you can make an average that takes this into account. State-of-the-art clocks seldom work continuously so you need something else as a flywheel between operating times.
The main use for very good clocks is as frequency references, or to measure the time interval between two events (in which case any offset cancels out) rather than time of day references. Sub-nanosecond synchronisation of distributed systems is only used in some very specialised scientific applications like Very Long Baseline Interferometric telescopes.
You can sync it with existing clocks to an accuracy of perhaps 500 picoseconds using well-established techniques like GPS-carrier phase and Two-way Satellite Time-Transfer.
Not sure if the parent is simply being funny, but
No atomic clock is ever 'reset' because of leap seconds. All they produce is a one-pulse-per-second 'tick'. The labels on those ticks are completely arbitrary. When a leap second occurs, you just change the labels
The receiver might cost $60 an antenna suitable for permanent outdoor installation might cost the same, but running cable to the roof, assuming that's possible, could easily cost a few thousand dollars to do properly. You'll want lightning protection too, if you're running the antenna cable down in to your server racks.
But for nearly everyone, as others point out, the 10 ms or so accuracy you will get from a nearby NTP server, is more than enough.
In short, "counting vibrations" is a poor description of what's going on. In the case of a caesium fountain, what you're doing is driving a resonant transition in the atom with external microwaves. When the microwaves are tuned to the transition, the Cs atom changes its state, which can be detected. To make the microwaves, you usually start with something like a very good 5 MHz crystal oscillator and multiply it up (plus add an offset, also derived from the crystal) to get the transition frequency ( for the transition in Cs which defines what one second is, this is an exact frequency) . You then adjust the frequency of the crystal (this is done electrically) until you're centred on the resonance in the Cs atom. So then you can just electrically count the oscillations of the crystal and 5000000 of these will be your definition of what one second is.
I use LabVIEW for FPGA programming, with other LabVIEW code running on a real-time controller interfaced to the FPGA, with top-level control, logging etc on a PC. LabVIEW is nice for the FPGA because the metaphor suits the parallelism of FPGAs. Part of why it works too is that you're only dealing with a very limited subset of LabVIEW's functionality and you can't do complicated things, at least if you want to clock at high speed.
But the code running on the real-time controller and PC
From the article "Gary Shu, XYZprinting's market development division senior manager, said the 3D printer can quickly create objects that users may need in their homes, such as a plastic cup or a plastic spoon.". I hope he comes up with a few better ideas than that.
Actually, a 3D printer would be useful to me for hobby projects like cosplay props, although probably a bit expensive. But around the house ? I look around for things completely made out of plastic that it would be practical to print if they broke or I needed another one but it's a struggle.
I suppose what all of these 3D printer manufacturers want to convince themselves and their investors is that there is a mass market for their product. The cheap printers still look very much like a hobbyist tool to me though.
There's a mistake in your calculation. As you say, a 1 m^2 panel produces about 200 W of power. But for ten hours of sunlight that's 2 kWh of energy. So everything improves by a factor of ten.
In any case, I wonder if someone could combine all that with the 36 dramatic situations and a few other components, and create a program that writes stories....
I think your summary is right. Skimming the article
I get the same impression. In the paper they say that you have to be careful to design your tests to catch all the errors that would affect the answer. The summary doesn't say it, but one significant aspect of the work is that it is the first experimental demonstration of verification of a quantum computation.