Rivers (e.g. Mississipi) work with much smaller gradient of just 0.01% [1], while with your assumption it would be 0.25%, so 25x.
Maybe instead it needs to pass under the rivers [2: cross-section] surrounding New-York, which may be much deeper, especially when it comes closer to the bay passing Queens and Brooklyn [2: map]
This piqued my interest, so I checked: Tunnel #3 passes under the Harlem River and then the East River, but the Harlem River is less than 30 feet deep for the most part and the East River is around 40 feet deep at the most.
(The Army Corps of Engineers has great detailed depth surveys for most of NY's waterways[1].)
Edit: There's also a higher-resolution render of the tunnel layout here[2].
As a user of WhiteRabbit, I can confirm a sub-10ps sync (two clocks phase lock) over 50km fiber connection for variable temperature of fiber (biggest problem of clock sync over fibers is temperature induced length change of the fiber itself, which needs to be measured and compensated).
The standards-compliant endpoints do all of the work. They count clock cycles for ping pong messages and share with each other the length of time so time-of-flight is tracked and compensated for.
As of now, for testing, the two WR endpoints are sitting on the same desk with 50km fiber in a thermal chamber (simulating temperature changes in the soil), but in future they will be separated indeed.
Nature (laws of physics) is agains you on this: it is in fact impossible for everyone. What is in sync for some observers can be out of sync for others (depends on where they are, i.e. gravity, and how they relatively move). See general and special relativity principle of simultaneity [1].
I think you just nerd-sniped me but I’m not convinced it’s impossible to assign a consistent ordering to events with relativistic separations.
For starters, the spacetime interval between two events IS a Lorentz invariant quantity. That could probably be used to establish a universal order for timelike separations between events. I suspect that you could use a reference clock, like a pulsar or something to act as an event against which to measure the spacetime interval to other events, and use that for ordering. Any events separated by a light-like interval are essentially simultaneous to all observers under that measure.
The problem comes for events with a space like or light like separation. In that case, the spacetime interval is still conserved, but I’m not sure how you assign order to them. Perhaps the same system works without modification, but I’m not sure.
For any space-like event you can find reference frames where things happen in different order. For the time-like situation you described the order indeed exists within the cone, which is to say that causality exists.
You can still order them with the spacetime interval compared to a reference event, even for space like separated events.
It allows for differing elements of the set to share the same value but so does using time alone. It just also allows every observer to agree on the ordering.
Bc Assigning a distance function to elements of a set is a common way to do that in fact. It doesn’t work with just a time coordinate or space coordinate, because that’s effectively a Euclidean metric.
You just have to contend with a few nonintuitive aspects but it’s not so bad.
Actually even within Apple ecosystem not all devices are made equal. MacBooks lack some features available for AirPods Pro on iPhones, e.g. seal check, translation, everything in the "accessibility" category: button press duration settings, single-airpod noise-cancelling, etc.
Android obviously is out of the game totally for AirPods - no spacial audio, no changes of ANC, no battery level, but at least ANC modes can be changed on AirPods directly, and button press works to answer calls, and pause/play audio, and also volume control works.
I'm three-generation Airpods Pro (around 5 years) user on Android and Macbook (no iPhone at all). In first and second generation there was a "bug" (or intentional feature) that even when connected to Android, and not being connected to my Mac, the latter was showing the charge level on both Airpods, but at some point it was removed.
In first and second generation I had an issue with one AirPod making strange noises, in both cases even Apple Support at the Genius Bar didn't know what to make out of it that I don't use AirPods with iPhone, but only with a Mac (and Android).
I would actually consider sticking the opposite "Nuclear power? Yes, please!" (Same for solar, wind, geothermal of course). Is there a sticker for pro-nuclear power movement?
P.S. There's a nice recent video to have a glimpse into nuclear power plant safety in action: https://youtu.be/v0afQ6w3Bjw
Answering to your and original question above: there are no poles (or axes of rotation) in the Universe. On large scales (think distances to include thousands and millions of galaxies each with billions of stars with even more planets) the Universe is uniform - isotropic and homogeneous [1]. It is expanding with acceleration in all direction in each and every point of its space, so there is no preferred direction thus in average we should have 50% of clockwise and 50% of counter-clockwise galaxies since orientation of those should also be absolutely random in average, unless something when the Universe was being created or evolving affected that balance.
Dumb question time continues: The majority of the solar planets rotate in the same way, and the majority of the large moons rotate in the same direction as their planets. I assume this is influenced by the rotation of the relevant accretion disks. And I assume this is common for stars within a galaxy?
I don't think the universe is considered to have any significant rotation, however. Is this due to scale for us to measure, and/or having nothing external to compare against?
That's exactly it. Solar systems and galaxies have net rotation, and maybe even galactic clusters.
But there is no reason to think that the universe has a net rotation. It could have one; you don't need a frame of reference to detect rotation. (The same way you feel centrifugal force.)
It would be huge if it were shown to have a net rotation. So huge that I take this claim with skepticism until heavily confirmed.
So it makes about as much sense to ask why 2/3rds of the galaxies are "upside-down" from our vantage point, because there's no clear reason it should be something other than 50% in a sample size this large?
5. Advances in the multi-messenger observations, where apart of photons and gravitational waves, astronomers can detects also neutrinos with specialized neutrino detectors, e.g.: IceCube [a], though there are many more of those [b].
6. Advances in very-long-baseline interferometry [c] using a globe-sized array of radio-telescopes, like Event Horizon Telescope [d]
7. The LISA mission is underway to build a space-based detector for gravitational waves at the 0.1hz region, whereas LIGO is sensitive around the 500hz region. 500hz corresponds to inspiraling stellar mass black holes. 0.1hz corresponds to inspiraling supermassive black holes. Think about the most powerful subwoofer the laws of physics allow, given the maximum amount of mass density in a volume and the speed of light.
Some technologies have been lost, even though they were superior to what is available today. Take, for example, the old “green/blue screen” technique using sodium vapor lamps, used by Walt Disney in film production in the pre-digital era: https://youtu.be/UQuIVsNzqDk (12 minutes long, but totally worth it).
The video also highlights how finicky that technique is to work with. Especially when working on film, where you have to wait for the developed dailies to check the quality of the work, any reliability issues with the effects processes compound enormously. Re-shooting scenes days later because the camera or lighting was subtly inadequate is expensive.
Generally I agree, but Moon is not a bad place for solar panels if a spacecraft has no contingencies and is able to harvest energy during Moon's day and store it in batteries to be used over the night. The sufficient power can be generated by a solar panel of the size (or even smaller) of the spacecraft itself. The other story is for missions like Juno [1] or Europa Clipper [2] which use solar panels near Jupiter - instead of centering develoment and mass budget around payload most of the spacecraft is an enourmously sized solar array. Juno panels generate 14kW on Earth orbit and only 500W near Jupiter [1].
Another non-obvious problem is that RTGs, as any other thermal machines, need a gradient of temperature to work, i.e. to generate electrical power there should be hot (nuclear material) and cold (radiators) side. On interplanetary spacecraft (Voyager, New horizons) Sun is in a predictable (and stable) direction so RTG's radiators can be put in a permanent shadow of the spacecraft. On the Moon the sun is moving, and there is no atmosphere (unlike on Mars where RTGs are used), so on a small spacecraft RTG will need to be dug deep into the regolith which is absoluteky non-trivial since just landing straight sometimes is a problem.
There are always tradeoffs, it is almost never "why don't they just" case in spacecraft development.
Maybe instead it needs to pass under the rivers [2: cross-section] surrounding New-York, which may be much deeper, especially when it comes closer to the bay passing Queens and Brooklyn [2: map]
1. https://en.wikipedia.org/wiki/Mississippi_River
2. https://gordonsurbanmorphology.wordpress.com/2014/10/26/wate...
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