In grade school i learned it was about 32 ft/s2, but by high school on it was all 9.8[1/06] m/s2. Then in engineering school it was sometimes 10. None of that had anything to do with local gravity and everything to do with Americans having to be special at first, followed by the fact that our science classes are actually in metric (statics and dynamics were in both as some fields of engineering haven’t metricated yet here). And the 10 is because you can round to a round number by barely even touching your fudge factor so why not.
I was going to say that even here in the US it was 9.81 m/s^2. I don’t remember ever being taught the number in feet (in NYS) nor seeing it for my kids (in MA). Science was always metric
Ohio, and Catholic schools. It was clearly on its way out. In retrospect it was definitely a strange situation where different teachers had different opinions on metric. Some clearly thought it’s fine for science, and others clearly just wanted to quit our two measurement system that does nothing but prolongs the inevitable.
I’d say the most important part is moisture. When a desert starts getting more rainwater, it starts to be an interesting habitat for algea and cyanobacteria (all they need is sun and moisture). These organisms start colonizing the desert, because it’s not hostile for them anymore. As they live and die there, organic matter starts to pile up and allows other organisms that consume this matter to colonize the desert as well. Soil is slowly developing and allowing more and more plants and animals to inhabit the place. The whole proces is very slow. You can do the same (and faster) through artificial means, but you have to water the land and take the water from somewhere else. If you stop watering, the land turns into desert again if there’s not enough rainfall. At some places that are not dry naturally you could reestablish a long term green habitat - e.g. instead of a dam and dry land surrounding it, you could recreate a wetland forest with a meandering river, which would help the surrounding area, because forests create their own small water cycles so more rain can be expected around them.
…and then to register astronomical observations! The birth of science, no less.
And all because every year like clockwork, the Eufrates and Tigris blanketed an area of hundreds of square kilometers with a fresh coat of silt (from the Taurus mountains in modern-day Turkey) that was perfect as a rudimentary but cheap, easy and quick writing medium, pushing the point of a stick into a pancake of soft clay, then leaving it to dry and harden in the sun.
I don’t know what chain reaction exactly they were thinking of, but from modern fusion research, I believe we can confidently say that the atmosphere would need to be interior-of-a-large-star-level dense, and even then I’m not sure you’d get nitrogen fusing with anything without a lot of hydrogen or helium around. Nitrogen-nitrogen fusion seems extremely implausible for sure
Prolly the most relevant paragraph from the linked article for this discussion:
Today, especially after the detonation of the 50 MT Tsar hydrogen bomb on Novaya Zemlya in 1961, it is also experimentally verified that the danger of atmospheric or even oceanic ignition does not exist. Also, the experimental measurements obtained by Zucker and others demonstrate that the fusion probability is much smaller than the geometric cross-section for 14N+14N assumed by Teller and coworkers, further reducing the chances for such an event. Furthermore, the atmosphere is also heated only to temperatures of a few million degrees, so that the most efficient energies of the fusing nuclei are a few 100 keV and thus well below the Coulomb barrier and very much reduced by penetrability. These temperatures are noticeably lower than those in the late hydrostatic burning stages of massive stars.
Basically the temperature of the atmosphere is over an order of magnitude too low to have any chance of ignition (need 10s of millions of K), and the reaction rate is thus several orders of magnitude lower than the threshold.
i think the idea is that the part that already fused creates a blast wave that could create the conditions, including preassure required for more fusion. i have no idea if it’s possible though.
…based upon how my elementary school teachers used to grade assignments, great is just above excellent, so they’ll diminish to excellent lakes first, then good lakes, then typical lakes…
My main question, and the one that I initially came here to ask, is: if their ship continues applying the force that, under classical mechanics, was enough to accelerate them at 9.81 ms^-2^, would the people inside still experience Earth-like artificial gravity, even though their velocity as measured by an observer is now increasing at less than that rate?
Relativity says yes. There’s no absolute speed, only relative speed; within the local reference frame of the ship, everything will continue to work normally, including the force experienced due to acceleration.
My understanding is that a trip taken at the speed of light would actually feel instantaneous to the traveller, while taking distance/speed of light to a stationary observer.
The ship is not actually going to reach the speed of light (as seen by an outside observer) though. The faster the ship goes, the more its (observed) mass increases, and the 9.8m/s² acceleration will have less and less of an effect. But to the people inside the ship, it appears as though they can accelerate indefinitely, going faster and faster at their steady rate of acceleration. Due to relativistic effects, it’ll never look like they are passing any objects outside the ship at more than the speed of light; instead it will appear as though the distance they have to travel is compressed, so they don’t have to travel as far.
You’re not allowed to have any way to determine an absolute speed. If your perceived acceleration were to vary (for a constant thrust) depending on your speed, that would give you a mechanism to determine absolute speed, but absolute speed doesn’t exist in relativity.
Rather than “nothing can go faster than the speed of light,” given that we’ve just determined that absolute speed doesn’t exist, the next rule is instead: you are not allowed to observe anything travelling faster than the speed of light relative to you, and relativistic effects will ensure that this is so.
A minor nit pick. It’s worth noting that increasing mass is an inaccurate view. It works in the simple examples, but can cause confusion down the line.
Instead, an additional term is introduced. This term, while it could be combined with the mass, is actually a vector, not a scalar. It has both value and direction, not just value. This turns your relativistic mass into a vector. Your mass changes, depending on the direction of the force acting on it! Keeping it as a separate vector can improve both calculations and comprehension, since comparable terms appear elsewhere (namely with time dilation and length contraction).
Also, metals can easily accommodate varying number of electrons in the electron shells of their atoms and still be stable. That makes them very good to quickly store and release electrons which means they can help say transfer molecules around (iron for transport of gasses), scavenge free radicals (e.g. manganese) etc.
Perhaps I’m not understanding the question, but first and foremost, science is specifically not a belief system. My professors emphasized the fact that we were not to believe anything but rather accept or reject hypotheses based on evidence. Science is a tool. It’s a system of observing, recording, hypothesizing, testing, analyzing, and refining. If you’re asking when we will have refined everything to the point that there are no more questions, I don’t think that will ever happen. What I’ve found is the more questions you answer, the more questions you have.
I don’t think it really makes a difference unless you’re really into feng shui. The best position for your bed is whichever one allows you to sleep most comfortably
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