To be even more pedantic, it is 60-80% of the speed of light through vacuum. Because the speed of light in those media is 60-80% of the speed of light in vacuum.
For most use cases that's true. But for a surprisingly large number of use cases that's not true at all.
I was thinking of using a high-frequency trading example, but here's a case that's a bit more normal: stadium concert audio for a live band. Stadiums are big enough that you need to deal with latency issues for audio, because the back of the venue will get its audio a bit later than the front of the venue (assuming the sound is wired so the board is in the front of the floor and no adjustments are made). That is obviously disconcerting to the audience. Adjustments usually are made to handle this problem.
If it was instant we wouldn’t have latency and the three generals problem would be somewhat trivial (ordering would be mildly interesting in an algorithmic sense, but practically meaningless).
we were hungry so we decided to discuss this philosophically over a pasta lunch, but we deadlocked with our forks and that dispute kept us from our main topic
Maybe because graduate students directly contribute to the university’s mission by teaching undergrads and “producing” research (both of which bring in $$$), while administrators seem to be purely a cost center, many of whom serve no useful purpose?
I mean, the grants that are being cut is the money that graduate students bring in. Less grant money -> fewer graduate students. In theory maybe it's possible to be more efficient like you're suggesting, but it's hard to see how the immediate response could be any different.
> Doesn't the US have access to all the data of non US citizens whose data is stored in the US without any oversight?
Er, no...? I'm not sure where you get that idea. Access requires a warrant, and companies are not compelled to build systems which enable them to decrypt all data covered by the warrant.
See, for example, the Las Vegas shooter case, where Apple refused to create an iOS build that would bypass iCloud security.
I asked if your Android backup is encrypted. Implies I'm talking about unencrypted data.
> See, for example, the Las Vegas shooter case
I am not in Las Vegas or anywhere else in the US. So as far as i know all the data about me that is stored in the US is easily accessible without a warrant unless it's encrypted with a key that's not available with the storage.
> companies are not compelled to build systems which enable them to decrypt all data covered by the warrant
Again, not what I was talking about.
I'm merely pointing out that your data is not necessarily encrypted, and that the "rest of the world" was already unprotected vs at least one state. The UK joining in would just add another.
This is why Apple, and more recently Google, create systems where they don't have access to your unencrypted data on their servers.
> Google Maps is changing the way it handles your location data. Instead of backing up your data to the cloud, Google will soon store it locally on your device.
Which is why Apple takes the stance that the users device shouldn't be sending data to the mothership at all, if it isn't absolutely necessary.
Compare Apple Maps and Google Maps.
Google initially hoovered up all your location data and kept it forever. They learned from Waze that one use case for location data was keeping your map data updated.
Apple figured out how to accomplish the goal of keeping map data updated without storing private user data that could be subject to a subpoena.
> “We specifically don’t collect data, even from point A to point B,” notes Cue. “We collect data — when we do it — in an anonymous fashion, in subsections of the whole, so we couldn’t even say that there is a person that went from point A to point B.
The segments that he is referring to are sliced out of any given person’s navigation session. Neither the beginning or the end of any trip is ever transmitted to Apple. Rotating identifiers, not personal information, are assigned to any data sent to Apple... Apple is working very hard here to not know anything about its users.
Google or Apple could be forced by authorities to perform correlation on the map tiles being requested by users under investigation. Not as accurate as GPS coordinates but probably useful nonetheless.
One more reason to prefer offline maps for those who value privacy.
Given that you can browse map data for any location, not just where you happen to be, I'm betting that triangulation data from your carrier would be more accurate.
Sure, triangulation of carrier signals could lead to more accurate position estimates, but if the carrier isn't based in the US they are under no obligation to make this data available to US authorities.
Apple and Google are based in the US so are bound by the CLOUD Act to provide any and all data they have upon request, no matter where in the world it is being collected or stored.
Google had "created a system where they don't have access to your data on their servers" a couple of years BEFORE Apple. Android 10 introduced it in 2019.
Google didn't announce plans to stop storing a copy of user location data on their servers until the middle of last year.
See the story linked above.
They didn't announce that they could no longer access user location data on their servers to respond to geofence warrants until the last quarter of 2024.
Were talking about protecting your personal data from government overreach, and Google's entire business model is to collect as much of your personal data as possible and store it on their servers to make ad sales more profitable.
Apple does its best not to collect personal data in the first place.
> all the data about me that is stored in the US is easily accessible without a warrant
No, law enforcement needs a warrant to legally access any data. This is why Prism was illegal, and why companies like Google are pushing back against overly broad geofence search warrants.
Upsetting... but surely not surprising? Europe and the previous administration were making existential threats, and the new guy offered to either pile on or make it all go away... for a price.
* Facebook was offered the option of either cutting their EU profits to zero or facing equivalent fines.
* Very Serious People were having Very Serious Discussions about whether Google should be allowed to run auctions for ad space on their own home page. At the same time, the two sides of the Atlantic cannot agree whether to make the web a Chrome monopoly or to only allow Google offer its services through 3rd party platforms controlled by competitors.
* Apple's whole brand proposition is being actively undermined. Apparently their monopolistic 30% market share does not demonstrate that consumers want a choice of something different from the competition (and legislators know consumers better than they do themselves).
* Amazon is somehow subject to expensive-to-comply-with restrictions, yet none of their similar-size in-market competitors are. Because reasons.
Surely it was predictable that they would all support a politician who offers to deliver them from regulations that not just limit profit but actively erode ongoing viability of the business, no? I guess you could call it the "Brussels effect".
None of these are "existential" threats, just relatively minor inconveniences for companies their size. And it's not like regulation will go away in the EU just because Trump comes to power. In fact, given that the administration seems actively hostile towards European democracy, I suspect EU countries will want to assert their sovereignty by bringing down the regulatory hammer.
I suppose that really depends on how hard they’re trying to prevent you from doing that…
* They could measure the forward voltage of the LED when driven by a known current. Bonus points for measuring at multiple currents. Remember that the forward voltage depends on color.
* They could measure the reverse leakage current at a known voltage, and compare that to the illumination from the camera’s exposure feedback. Remember that every LED is also a photodiode.
* They could vary the LED driver current to heat it up, then measure that both of the above measurements are compatible with the higher temperature. Remember that most semiconductor properties have a strong temperature dependence.
So it would be pretty easy to detect most simple mods if they really wanted to.
> The article mentions "saves weight and installation space" - it seems this savings come at the expense of massive complexity; how big can the savings be?
Take a step back and look at how complex brake systems have evolved at the present date:
On one hand, sure, it's just a foot-operated hydraulic pump and four hydraulic actuators.
On the other hand, the ABS module has valves to both cut off each brake caliper and to drain hydraulic pressure from each brake to prevent lockup. In an emergency braking scenario, the foot pump will quickly go the floor as pressure is drained, so the ABS module also has an electrical pump to put fluid back into the system.
All US-legal cars have some form of electronic stability control (and often have lane keep assist), which can use the same components to pressurize one or several brakes to make the car follow the driver's intent (as measured by a steering wheel angle sensor and a body yaw rate sensor. Europe-legal cars also usually some form of emergency brake assist which again uses the ABS module components to apply the brakes automatically.
To keep this all safe, you need pressure sensors to monitor valve and pump functions, sensors to monitor driver input, and sensors to monitor vehicle dynamics.
When you look at the system holistically, as it exists today, it is bandaids on top of bandaids and you realize that you no longer have just a simple hydraulic system.
I would make an analogy to the 737 Max vs. Airbus FbW here: We started with something very simple, and then incrementally increased complexity in (seemingly) appropriate ways. Then, many years later, we realized that our "simple" mechanical system is actually more complex and prone to more complex failure modes than a system which started out complex and rigorously managed that complexity.
Funnily enough, A380, A350, B787, and other new aircraft have their brakes connected by Ethernet (specifically AFDX, a modified variant of Ethernet) so braking actuator signals (and sensor data back) goes as UDP messages.
But it makes the system less complex and easier to handle, as there's one kind of cabling, and complex functions like ABS equivalent are handled from avionics bay
Aircraft don't need their brakes to be as responsive as cars do. There is virtually no chance of hitting a person or another plane while landing or maneuvering on the runway.
Aircraft brakes are life or death issues that require instant response times to changing conditions, which is why ABS originated in aircraft.
The aircraft braking systems are very complex, including active thermal management and automated braking systems that take multiple data sources to manipulate breaking force, including understand how long the brakes survive when taken beyond melting point (RTO setting on autobrake)
I don't think ABS originated in aircraft because of the required braking response time. It originated in aircraft because aircraft must regularly operate in wet and icy conditions, and the performance of aircraft brakes is correlated to the length of runway required to land, which relates closely to the cost of everything in aviation. It was thus economical to use cutting-edge tech on planes long before it was economical to do the same for cars, which are mass-produced and must be affordable to individuals.
There is approximately zero chance of an aircraft pilot needing to stomp on the brakes because of a random pedestrian or animal, whereas that happens constantly for cars. Cars stop and go all the time and have to avoid each other. Aircraft hardly do that at all when they are on the runway. They use their brakes to not accidentally roll or be blown about, and in the process of landing. Those applications don't need epic response time.
Being slightly off in adjustment of brakes when landing an airliner results in dead passengers. It's not as visible for manual braking, but that's because the brakes have been "brake by wire" for some time. The scope of inputs in brake control loop is also much wider in aircraft than in typical car, at times including calculated mass, calculated ground speed, brake temperatures, tire temperatures, pressure on gear, etc.
Now consider that the same network used to control the brakes also is sufficient to control every other sensor and servo on the aircraft s well.
That is all pretty interesting but I think we've gotten far away from my original comment, which was that planes don't need brakes to be as responsive as cars do. The typical application you're describing is in landing, not in puttering around in the airport. Landing involves executing some braking program continuously until the plane is on the ground. What I'm really getting at here is that the pilot is not going to be taken by surprise and have to apply the brakes in the same way as a driver would. It stands to reason that despite the lower speeds that cars go, they need to brake spontaneously in all kinds of conditions (on worse surfaces than the typical runway, in many cases). I don't know why this point matters anymore but that's what I was trying to say.
I would like to add, brake by wire may be more reliable on planes than cars because planes are maintained very well by experts. Automobile design should strive for simpler and more failsafe options because owners are usually clueless people with limited budgets, who want to do as little maintenance as possible. The fact that hydraulic brakes work so well even in very old cars says a lot about how good they are. When they do get blamed for poor performance, it's usually due to something stupid like the owner not replacing worn out hoses after 20+ years of heavy use. I only found out about that one recently. Old hoses start breaking down and they gradually get congested.
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