The church has been using logic in the study of religion for thousands of years. This is no different. One way or another asking questions and thinking about problems is OK.
Keep in mind C is just basically assembly but encapsulated in a pretty package. If you create small executables and dump out the generated unoptimized assembly you'll be surprised just how simple it is. It pretty much just encapsulates the ideas of System V binary compatibility and then keeps going. So developing a language from scratch and skipping the use of C would really likely be just causing yourself more pain than you need as you're going to have to replicate all of the things C does anyways, so why not reuse what the experts have already done. And you get a lot of cross CPU and cross compiler portability.
What you want is the idea of bootstrapping. Write your compiler in C, then as your language specification is developed enough, dogfood your own compiler. Write your compiler in your new language, then compile itself. This is called bootstrapping and is how many languages are developed. Once you are fully bootstrapped you can drop C altogether.
For portability by far the vast majority will say C. In my experience the C compiler optimizer will do a lot with -O2 or -03 but it can't always infer correct SIMD optimization for some operations and on occasion you have to drop down into x86_64 assembly. The idea is do most things in C and use __asm__ to write custom assembly instructions. With #defines around the assembly for each processor you plan on supporting you get the benefit of both C optimizers and portability across different CPUs as well as any future updates to the compiler in the future. But the compiler writers will say to use intrinsics and extended assembly rather than raw assembly because when you write raw assembly your code becomes a black box to the compiler and it can't infer optimizations for your surrounding code that interfaces with the assembly. I think C with extended Asm is likely the most sane combination if you don't mind the slightly ugly syntax and the fact that there could be differences between compilers. That being said, C with compiler intrinsics seems to be a happy compromise for those that don't want to shift around registers and deal with the stack.
I don't use Rust so I can't comment on it but it also has compiler intrinsics + a memory safety model. It's compiler is really dog slow last time I used it so I hope that has improved but nobody is really killing C any time soon, even if there's enthusiasm for memory safety. Sooner or later you have to delve down into the depths of Narnia and you may as well get comfortable dealing with memory.
My likely favorite combination is Python + C (for the speed stuff) + Intrinsics (for the really speed stuff).
This is an apt observation. Anything negative. Even if true. Even if it doesn't reflect on you. They want someone socially aware enough that they can say negative things without saying anything negative. There's a nuance. "I understand where they're coming from. There's definitely situations where that is preferred", translates to "I disagree totally but it's their prerogative so I'm not going to worry myself too much with that decision."
It shows experience with people and ability to read between the lines.
There was a really good episode of the Odd Lots podcast where they discussed this. Arizona is a very favorable location for semiconductor fabs because there's a very low risk for natural disaster (no hurricanes or earthquakes), the temperature changes are relatively predictable, land and electricity are relatively cheap, and Intel already has a large fab there. Water is a little bit of a struggle, but they can buy water rights from farmers, who use most of Arizona's water.
>> "but they can buy water rights from farmers, who use most of Arizona's water."
They probably waste less water, so this might be a net positive for the environment. Abuse of water rights given out in a very different time is a major point of contention in the desert region of the country.
It's dry, weather is consistent(though hot), has a robust power grid, has an engineering school who produces semiconductor grads, has a large pre-existing industrial base and has ready access to water (the plant is literally next to a 340 mile water canal that runs from the Colorado river and sits atop a water basin that has had water levels rising since the 80s).
I'm not sure there are many better places outside Oregon, California or Texas...
As others have mentioned there is a large Intel fab (and other smaller fabs) in the area. I suspect this gives them insights into the feasibility of success there and also means there is an existing talent pool to draw from. It basically de-risks the investment. There are probably only a handful of likely places to do this - OR, CA, AZ, TX, maybe NY. Intel building in OH is more difficult from a bootstraping perspective.
Ask them for a landline phone. They'll either have to run new copper or choose to install fiber. Once they run copper then get a DSL company to run through that. Generally they won't want to run copper and don't want competition so they'll go ahead and run fiber. In either case I believe the law they're constrained by is local ordinances giving them a region based monopoly for traditional landline access in exchange for ensuring everyone has a phone. If you force the issue they'll run SOMETHING to your door. And through that something you'll have more options.
Will they still run copper? Out here on Long Island Verizon will not install new copper and existing cu lines are on 3rd party life support. Work had to replace a copper phone line for the fire alarm with an internet bridge and wireless backup after it went dead and the tech told us "We don't run new copper."
In a bunch of areas the companies rely on legal monopolies that were given to them by the local governments. The agreement was they get a monopoly if they agree to install phone lines for everyone who asks. If they don't run copper then the next thing they'll do is run whatever is their preferred equivalent. It's a quasi government+private monopoly agreement that benefits both and ensures residents get phone lines.
Correct. This is all based on my previous knowledge of my local monopoly agreements that someone told me about years ago. They refused for months to install internet until I asked people in my vicinity if anyone had asked for a phone line. Nobody had. So I did and instead of copper they ran fiber within 2 weeks.
I can only infer what happened but they really didn't want me to be without a regular phone line so I determined that was their legal weakness. The only way companies that large move like that is if something threatens their status with the local government. A call from a resident saying the company wouldn't install a phone line is a big no-no in my understanding.
In my area (Washington State, USA) this doesn't happen.
If you ask for phone service, Comcast will sell you a "landline" that just consists of a combo box cable modem and VoIP ATA. You can buy it with internet access or without, and they still give you the same equipment. The ATA part gives you an analog phone line to connect to your house phone wiring, but everything outside the house runs over existing coax infrastructure.
Maybe I'm not asking the right questions? It seems exceedingly difficult to get services over actual copper.
No guarantees bc it entirely relies on your local ordinances, but it did work for me when the company was giving me the runaround about internet. I just asked for a landline phone and they had fiber installed within 2 weeks.
Just got done watching all of the seasons again (for the third time). I keep forgetting how incredibly sad the last few episodes are. It's a gut punch every time especially knowing the reality of how many of the actors have passed on since. One of the only shows that properly ends and gives a sense of closure. Almost too good.
One of my favorite shows of all time. Excited to watch anything that's even remotely related to this.
I really really hate how Sheridan doesn't die at the end; I felt Lorien saving him at the last minute with this meta-physical "beyond the rim" crap really took the punch out of things. In general I felt all that meta-physical stuff like "humans will evolve in to beings of pure light and goodness" was one of the weakest aspects of the show.
It's still a good episode overall, but the last minute or so really ruined it IMO.
It's a risk if you don't swap the filter regularly as recommended by the manufacturer, and everything downstream of the filter (tubing etc) is at elevated risk for biofilm buildup when the filter is stripping out chlorine/chloramine.
It's an even bigger risk, generally, with pitcher/reservoir type systems (e.g. Brita or Pur) that require manual fills, given that they get a lot of environmental exposure. If you use a Brita pitcher for a while and then leave the filter media and pitcher somewhere at room temp for a couple weeks, you can often see evidence of fungal/microbial growth popping out of the bottom of the filter cartridge. It's pretty gross. I've also had a relative end up in the hospital with a pretty severe amoebic infection, which investigators traced back to her Brita filter cartridge she had neglected to change for some time.
Part of the reason I purposefully bypassed the filter on my fridge. The tap water is fine and doesn't need filtering but an old water filter can cause all sorts of nastiness.
It's really shocking how ineffective things like pitcher filters are when compared to a quality cartridge filter. The pitcher filters really do practically nothing.
There's no question that Brita filters improve water taste by reducing chlorine/chloramine levels, and they will remove relatively large particulates, but they pale in comparison to proper pressure-driven cartridge filter systems if you start looking at comparisons for other contaminants.
Sure, but for people who are getting perfectly safe water from their municipal water supply, and just want to get rid of the chlorine taste -- that's where pitcher filters work perfectly. You don't need anything else.
It’s still probably not doing anything, chlorine readily evaporates out of water left in a pitcher. It’s a common technique used by indoor growers of certain plants - leave a bucket out for a day.
I can taste the water 5 minutes after it goes through the filter. The chlorine is gone. (Which is not the case if I pour it into a glass.) It has nothing to do with how long it sits around for.
I find it strange you're insisting filters don't work when one can tell from taste that they clearly do. And scientifically, activated carbon absorbs chlorine -- that's not a myth. So everything checks out.
Sure, they work for chlorine, but there are plenty of other issues (arsenic, PFCs, other VOCs, glyphosates, TTHMs, lead for non 'Elite' Brita filters) that Brita filters are woefully inadequate to address.
Actually, NYC is a major concern in terms of water quality because it's very common for buildings to have old plumbing that releases trace heavy metals, and many buildings use rooftop water reservoirs that are a common source of organic contaminants (and occasionally cause building-wide outbreaks of things like legionella).
Similar issues exist in most 'older' US cities. I started becoming worried about my water filter efficacy after moving to downtown DC and learning that a significant portion of the municipal water supply's last mile piping contains lead, and that while the municipal water is safe at the source, water in DC housing is often heavily contaminated by lead and other compounds resulting from the use of extremely aged pipe infrastructure.
I don't know whether or not this is a factor, but apparently the Goldstone Solar System Radar (GSSR) facility used can operate in either of two modes, monostatic in which the Goldstone facility both sends and receives radar transmissions, and bistatic in which Goldstone transmits whilst two other facilities receive the bounced signal.
It seems possible to me that for a near-earth object it might be possible for a bistatic image to show a perspective difference between the side nearest the transmission and receiving antennae.
Though at five times Earth-Lunar distance (about 2 million km), any such parallax baseline would be minimal (13 thousand km).
The postprocessing explanation offered elsewhere seems far more likely.
These images are confusing. The "lit" side is where the radar beam is coming from. The perspective is looking "down" on the asteroid with "up" on the image being the direction of Earth. The radar scans a beam across the object and records the reflections. The brightness of a pixel is a function of the strength, phase, and polarity of the returned signal. The position of a pixel is a function of its distance from the receiver.
From the perspective of the radar receiver it's just receiving a series of reflections over a period of time. These are processed for the above measures and then perspective transformed to show an "overhead" image that we see here.
It's not a bad heuristic that the "lit" (up) side is where the radar is coming from. That's the "delay" coordinate, so the top means small delay which means close to observer.
But the other (left/right) coordinate is doppler, which does not map 1:1 to a physical location -- doppler will depend on the rotation and geometry of the asteroid.
The radar beam is not "scanning" across the object. The asteroid is too small to focus the beam on a part of it -- the beam illuminates the whole object. We get lucky that the object is spinning, so that different surfaces on the asteroid cast energy into different doppler offsets.
Anyway, the returned signal is then binned into (delay, doppler) coordinates. This is repeated for many separate pings to beat down the receiver noise.
During the observation window (series of pings), you have to compensate for the relative motion of the earth and the centroid of the target, because the relative velocity (zero-point of the doppler coordinate) is changing the whole time.
The Sun emits microwaves that can be reflected by asteroids. Depending on the surface/composition it could be much more reflective to microwaves than visible light.
A 70 meter dish can emit and focus a powerful signal but probably can't outshine the Sun at these distances. Radar emissions also consist of short pulses while the Sun emissions are continuous.
Since the article mentions precise distance information being acquired, the radar system was able to detect it's own emissions (likely only from the unlit regions)
This is related to the periodic outages of geostationary satellites when the Sun is directly behind them. Ground receivers are essentially "jammed" by the microwaves emitted by the Sun itself.
Alas, the above comment is quite mistaken. The microwave reflection from sunlight is too faint to detect. All the information shown comes from the radar beam from Goldstone.
The radar imaging process is complex, but suffice to say the shown "image" is not in physical coordinates. If it's a conventional radar image, the vertical coordinate of the shown image is "delay" (distance from observer). And also conventionally, the horizontal image coordinate is "doppler", which is the doppler shift given to the returned signal by the rotating asteroid.
So, stuff on the left side of the image was moving away from the observer, and stuff on the right side was moving towards the observer. And of course the brightness is essentially the "amount of stuff" at that delay-doppler locus.
The reason we can't plot an "image" in physical coordinates, and have to be content with the altered coordinates, is that all we get from the returned radar carrier signal is a delay, and a doppler shift. That's it - "delay-doppler" coordinates.
So any set of sites on the asteroid surface with the same distance and the same relative velocity (w/r/t the observer) will be binned into the same place in the radar image. There is no guarantee that these sites are near each other, and for complex geometries (rough asteroids), they often will not be.
If you want to get a real image in physical coordinates, you have a separate inversion problem to solve, and you'll probably need more images and some model constraints.
Eh, your explanation makes it sound like the radar "image" is as divorced from physical coordinates as a spectrogram or a bar chart. Radar images are at least phyicalish... the asteroid does look similar to the image in real life. Doppler and range do roughly map to x/y. I hear it alot with SAR imagery as well - that we're not looking at a "physical representation". We are - there are just different anomalies to account for.
I’d agree partway, and I appreciate the counterpoint, in that the delay coordinate is simple. But Doppler for a rotating, irregular asteroid is not simple. See Fig. 1 of the paper I linked for an example. It really is many-to-one.
Delay-Doppler for planar surfaces, like a remote sensing radar zipping along Earth’s surface, is pretty straightforward, as you note…and we get to set up the system parameters, like beam width, pulse rate and ground speed, so it works out nicely.
I'm not at all plugged into astronomy, though I have worked in radar for quite awhile.
Can you comment at all why a technique like Inverse Synthetic Aperture Radar (ISAR) is not used? That relies on the rotation of an object to generate cross-range resolution through sampling a diverse set of aspect angles (and is certainly useful for non-uniform, non-planar surfaces). If the rotation rates of the asteroids are known, then that minimizes one of the main challenges in forming quality ISAR imagery. For the use-cases I'm familiar with, we need to estimate the rotational motion because vehicles do unfortunate things like accelerate and turn while we're trying to look at them -- the nerve! And ISAR has certainly existed before the paper you linked in another comment was written (and also before the previous study the paper itself references).
As a side note, that paper by Ostro et al. is very interesting to me; it's like being familiar with Leibniz's notation for calculus and seeing something written using Newton's notation (or vice-versa). I skimmed the references and all of the ones I saw seemed to be from astronomy / astrophysics sources. It's almost as though we have two fields using similar methodologies to look at different objects that don't seem to talk at all and have developed different dialects.
Edit: maybe delay-Doppler imaging is akin to ISAR, like medical tomography and SAR were shown to be mathematically related?
I know something about SAR and InSAR because I use radar (Earth) remote sensing in my day job, and I have a signal processing background. But I’m not a serious radar expert.
ISAR sounds like its operating principle is the same as the radar imaging technique used for these asteroid results. In general, it’s all radar imaging so you get reflectances in delay/Doppler coordinates as your observable.
One possible difference is the poor SNR of the asteroid problem — you have to average many radar images to beat down the noise. The velocity of the scattering elements on the asteroid is assumed to be the same across all these images (as far as I know). (After correcting for a known offset due to the Earth’s changing motion.)
This seems to be a little different than the ISAR “swaying boat” type of application in which the body is indeed accelerating and your radar image must be adjusted for that, or else the mast of the swaying boat will smear across the image.
It may also be worth saying that there is no synthetic aperture in the OP - it’s a physical aperture.
No, that’s not it. I believe that these are not true images. They are instead effectively graphs of the time of flight of the radar signals. The vertical axis is flipped, putting Earth (or rather the radio telescope) “above” the image and the bearing of the radar signal along the x axis. The shading happens because some fraction of the radar signal refracts instead of reflecting. You can think of this as reflecting off of the interior of the asteroid rather than the surface, or as reflecting off of internal features such as density or composition changes.
Our eyes interpret it as a top–down view, or as a face–on view with lighting from one side, but it’s really more like a slice through the middle. Or rather, like a bunch of slices through the middle all stacked on top of each other, since the beam probably isn’t all _that_ narrow after traveling for a few million miles.
I wish I could find the paper though; press releases so often don’t bother linking to them. Maybe it hasn’t even been published yet? The observations were just 19 days ago.
