I know China has done a lot of “regreening” of areas and I’ve read that the Sinai could be a good candidate for the same sort of restoration. It’s not my area of expertise but the best candidates seem to be areas that are deserts because of human activity (like over farming, excessive water use, etc.).
What China did was plant trees, restore nutrients to the soil, add terraces to hills, limit livestock, and other things that slow down water loss. They successfully regreened and area the size of France but I think, crucially, it got enough water naturally. The land was just depleted, which caused the water to wash away topsoil instead of support vegetation.
So, I don’t think we could realistically show up to an arid desert and turn it into much. But there’s places we think of as desert now that would be good candidates for restoration.
Naturally this kind of thing happens over tens or hundreds of thousands of years. So, even going back to BC times, we’re still only a small fraction of how far we need to go back to find really major, long-term climatic shifts. These things are supposed to happen sloooowwwwllly, not really discernable as changing over the scale of a single human lifetime, which is just the blink of an eye in planetary time scales.
Can we though? Probably. We can certainly dam rivers and use irrigation to make the land more agriculturally productive. But we should have the technology currently to attempt more dramatic geoengineering projects if we wished.
The problem though, is unintended consequences, where you change one thing over here, and you didn’t realize it was also controlling something else over there, and that thing changes too now, even though you didn’t necessarily want it to.
Like, to make up a fictional example, say we engineered rainfall over the Sahara somehow. But we didn’t know some of this moisture influences air currents, and now southern Europe and the Middle East are changing too somehow, by accident.
It’s like when you’re trying to untie a really tangled knot, and you pull on one part thinking its going to start undoing it, but it just tightens it somewhere else instead.
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.
When you say zoom in, what you are actually asking is what if the wall was a light year away, and you’re building the delayed choice version of the experiment, details here …m.wikipedia.org/…/Delayed-choice_quantum_eraser
But basically, the universe knows, and you can’t worm your way around it.if you detect which slit the photons flow through, then you lose the interference pattern.
A measurement device is necessarily local: if it’s “zooming in” from a light year away, it’s using transmitted particles to observe—and those particles are traveling (and entangled) with the particles you’re trying to observe.
If the measurement device were a light year away and were precise enough to “zoom in” and see which slit the electrons went through, what would happen on the final screen?
That level of precision implies technological advancement, that would result with far better equipment to perform the test and measure the results, providing they would be still needed.
I know it sounds like an attempt to brush the question off, but it’s Spherical Cow and/or Newton’s Flaming Laser Sword territory. 😉
The results of the double slit experiment and the uncertainty principle will not change with our level of technology. They are fundamental laws of nature.
The quality of the camera to observe the result of the double slit experiment (meaning the pattern on the wall) has no effect on the results.
The hardware, software, money involved and other variables required to conduct an experiment from a lightyear away definitely elevate the project to different level on Kardashev’s scale.
First, though, your premise is a bit off. Zooming in still wouldn’t change the speed of light or change how fast the photons take to get from point A to your zoom lens. Zooming doesn’t give you a time or distance shortcut - all zooming does is decrease the angle of view of whatever you are pointied at. The only thing that matters in the double slit experiment is whether you observe them enroute or if you observe the screen after impact. If the screen were between you and the photon sources and you zoomed in, the photons would still hit the screen first and the photons you observe through the lens would come after.
The TL/DR of that article I cited earlier is that we still know the field would collapse. The more interesting question (and the one they pose in the article that remains unanswered) is: how fast does the collapse propagate back to the source? Is the propagation delay of the collapse instant/infinite (like what would be described by entanglement) or is the speed of the collapse still subjected to the speed of light (which is the same for the propagation delay of gravitational waves)?
The links to the older articles are dead in that link. Here’s an archive of the 3rd essay (and it links to the second and first). The 3rd essay presents a thought experiment very close to what OP is asking. If we delay the choice of inserting a detector then would we still get an interference pattern when we’re not supposed to? It seems that the question is still unanswered but theoretically, no, because the universe is not locally real and quantum effects seem to happen faster than light in plenty of other experiments.
The “observation” doesn’t occur when a person sees the result, but rather when the electron or photon interacts with the device (in this case the wall). The wall is making the observation. In this situation “observation” doesn’t have the traditional meaning, but rather refers to an interaction event.
So the same average result will happen no matter where the device is, the only thing that changes is its proximity to you.
Most allergic reactions start with milder symptoms, and some get worse each time you’re exposed. You would probably notice (and hopefully see a doctor about) the burning/itchy/numb mouth and throat, and/or upset stomach, before it progressed to a lethal allergy
tl;dr no, i don’t think newly developed allergies can kill you. #notadoctor
did you have a peanut allergy earlier on? personally always had a mild allergy to basically everything. now i live with cats, who make it worse, but before that i was always sneezing and my eyes were going bonkers, regardless.
Possible, yes. Not likely though with most things if you have them regularly - your body kind of recognises it as something that isn’t a threat.
I’m of the opinion that more often than not allergies are your body reacting to the wrong thing. Take seafood allergies for example. The first time your face swells up and gets itchy after eating seafood isn’t the time you had bad seafood - that happened the time before. When you ate the bad seafood, your body reacted and got over it with minor fuss. However, it then tags seafood as the cause of what happened, and the next time you eat seafood you have an allergic reaction.
It is also sometimes possible to overcome allergies, although this is incredibly difficult.
You should feel bad for giving advice that can kill. You should not feel bad for correcting that bad advice and potentially saving lives.
Trust me. It’s my day job to make decisions where the wrong one can result in deaths. If you don’t feel bad when you inevitably make such a mistake, you are a sociopath and need to be told as much.
Besides the only reason I brought up my opinion of how he should feel is he tried to say I was attacking him, which at no point have I done.
What are you talking about? I do not mean “you” specifically. I certainly only said he was wrong exactly once, and I clearly referred to op in third person.
Where did I give any advice? Where have you offered any other information instead? All you’ve done is jump off the handle to say that I’m wrong and criticise me personally.
Yeah, that’s fair. I don’t think any lines have been crossed (yet) but the tone in the thread is certainly veering close to it. It’s also possible I missed a comment. Please don’t hesitate to report any uncivil or otherwise rule breaking comments.
There’s increasing evidence that it is lack of exposure to some allergens which causes problems. Current advice is to eat peanuts during pregnancy and to introduce peanut butter to baby diets early to reduce the risk of peanut allergy.
So you’re more likely to be reducing the risk. But there’s a lot we don’t properly understand yet, of course.
There had been long-standing advice to avoid foods that can trigger allergies during early childhood. At one point, families were once told to avoid peanut until their child was three years old.
However, evidence over the last 15 years has turned that on its head.
Instead, eating peanut while the immune system is still developing - and learning to recognise friend from foe - can reduce allergic reactions, experts say.
It’s basic math. You can do the gravitational calculations yourself. Basically any sphere of uniform density is going to exert gravity uniformly. So if you’re in the center the pull from the mass on any direction will be counteracted by the pull in the opposite direction. It’s one of the basic introduction to physics calculus examples.
So to your question about what the zone of negligible gravity would be, you can define negligible gravity, and then figure out how large that zone would be based on the material on the outside of the shell.
Basically the further you get from the exact center of the sphere, you’re going to have more gravity from the closer edge pulling you, and less gravity from the further edge offsetting that. So there’ll be a gradient of increasing gravity as you get further away from the center
This feels very close to answering the question in a way my brain can interpret it. So, going outward makes complete sense to me but the area at the center, the way I under your answer is, yes, the area or zone will increase proportional to its mass?
This may be asking too much, but, have any idea the size of that low gravity zone of earth bs our Sun?
I can’t answer that question for you. Because you’re using a relative term. Only the exact center will have no gravity. Anything outside the exact center will have some gravity. So you have to define what negligible it means.
So once you define low gravity. You can do the math to figure out the size of that zone of low gravity.
I highly recommend doing the math anyway. Follow along with a YouTube example or a written example on gravitational attraction of a sphere. It’s really good calculus. Then you can you know put it into octave and get the exact answer for yourself. Just plugging in numbers for the relative density of the Earth and the mass and the sizes. These will be approximate of course. Because nothing is perfectly uniformly dense so it’s just a rule of thumb anyway
Depends what you’re trying to do. If you want to balance something so it never moves you can only use the exact center. If you want something to stay relatively in the center for a period of hours then you’re going to have a much larger area. If you’re okay with minutes it’s going to be much much larger area. If it needs to be stable for years in the area is smaller. Gravity is going to apply a force of acceleration and on an object, and if there’s nothing resisting that acceleration things will just fall off the center. You know imagine trying to balance something on top of a cone.
My original question stemmed from thinking about the possible different area sizes of low gravity within different size stars - and if that area was gradient.
Not quite. If by “edge” you mean the surface of the earth, then the force of gravity from the closer edge will always exactly offset the gravity from the farther edge. So if the earth were hollow, then you would experience zero gravity at any point in the hollow portion.
Of course, the earth is not hollow. And any mass under you (i.e. closer to the center than you are) will not be offset, and all of it will pull you towards the center. As you move further away from the center, more of the earth’s mass will be closer to the center than you and therefore the force of gravity will increase.
So if the original poster wanted to have a 10km sphere in the center of the earth of zero gravity (earth gravity at least), then all they have to do is hollow out 10km and they are good to go?
Yes you can, as long as you are inside a perfectly spherical shell.
The net gravitational force on a point mass inside a spherical shell of mass is identically zero! Physically, this is a very important result because any spherically symmetric mass distribution outside the position of the test mass m can be build up as a series of such shells. This proves that the force from any spherically symmetric mass distribution on a mass inside its radius is zero.
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