studiot

Depends what you mean. Biological agents are now recognised as being responsible for geological changes in the Earth's history. But please remember that Roman posted this in homework help so we cannot do his project for him. @RomanRodinskiy You should research The great oxygenation event cyanobacteria stromatolites Here is a history of the atmousphere from Wikipedia It divides history into 5 stages and I asked if you are interested in stage 5 where the sort of organised multicellular life we know occured. Note the great oxygenation event occured ab little over 2 billionyears ago. This might provide a good framework for your project.

I guess you are asking about evidence for the origin of life ? This is difficult and complicated because when life started on Earth neither the ocean nor the atmousphere consisted of anything like the current composition. The original lifeforms changed both of these, introducing oxygen into the atmousphere (it didn't start of with any). This period started about 3.5 billion years ago and took 2.5 to 3 billion years and there were few lifeforms and things changed very slowly. Once the compositions had settled down to near current conditions geological evidence points to an 'explosion of lifeforms' (Sedgewick) about 0.5 billion years ago., in the Cambrian period. I think perhaps the life you are thinking of started at this time and led to the sequence of evolutionary development that results in the evidence for oxygen based life. Here is a summary of the biochemical evidence that supports the idea of seawaterborne development from The Nature of Biochemistry - Ernest Baldwin - Cambridge University Press. It is very persuasive to note that so many disparate land and marine creatures analyse down match to the chemical distribution of ions in seawater.

CHATGPT banned in Italy perhaps others to follow.

If you are not going to 'restore' - dry - the pink gel, what is the point of keeping them ? Once saturated they no longer protect your valuables.

As I said, I haven't tried a microwave but the net say it can be done but some sites are too gung ho for my taste. Here is a measured warning plus useful instructions. https://www.reddit.com/r/3Dprinting/comments/bwbvri/protip_microwave_your_silicadesiccant_to_dry_it/ This guy spread out the gel as I suggested before. https://homeguides.sfgate.com/dry-silica-gel-microwave-25024.html So I suppose it depends upon quantity. The second guy used bigger amounts. I remember changing the dessicant by the barrel load inside steel box girder bridges. One worry I have with a microwave is that it takes time to properly dry out. As soon as you remove the gel from the microwave it starts reabsorbing moisture from the atmousphere. A conventional oven will still be dry inside as the gel is allowed to cool.

I have no knowledge of using a microwave to dry out spent silica gel. We always used to heat it in a tray in a moderate dry (not gas) oven at 75 - 150 degreesC for a few hours. Do not let it get too hot or it will loose its hygroscopic (water absorbing) properties. Is anyone sure microwaving actually works ? Personally I would be worried about local overheating and degradation of the gel.

Like so many classification schemes, phenomenological v noumenoligical is very limited and incomplete. Yes I agree the idea is good and can serve a useful purpose, but I still consider that the plain old English concrete v abstract nouns covers more situations, which do not require the causal connection of ph v nou. For instance I have just used a couple of abstact nouns (classification) schemes and ideas. Is there a causal relationship between the idea and its realisation ?

Thanks for the reply and links. I thought you might be interested. I was wondering what sort of printable material would withstand rocket launch and propulsion techniques. PS I did my first bit of plastic welding repair recently, to a broken laundry stand boss. Was not so successful with my second repair attempt to a broken freezer handle.

Yup MigL has said it simply Nothing wakes up one morning and decide I am gong to 'evolve'. There is a whole formal theory of rock structure evolution. I don't agree. The Romans had piped fresh water and centrally heated buildings. 2,000 years later do we have better?

@Sensei get your 3D printer out and see what you can do. This rocket nearly made it. https://www.bbc.co.uk/news/science-environment-64893578

So what do you mean by evolution ? Do you mean change? That is a perfectly acceptable usage. Rocks 'evolve'.

Not too sure about any of this. The tread is entitled Human Evolution. Isn't this a strange idea ? After all if we evolved would we still be human ? I suppose it depends what you mean by 'evolution' ?

Actually the OP described a function since it used a letter for a variable, not a specific number. It is important to distinguish between a function and the value of that function at a specific point. A square root of a number is another number, a square root of a function is another function. So a square root of 4 is 2 and another square root is -2, all of which are numbers. Folks also often make this mistake with the differential calculus, where the derived function (the derivative) has, possibly different, values at every point where the original function is differentiable.

I agree wholeheartedly that deadly sins numbers 2 (greed) and gluttony (6) are between them the biggest obstacle to be overcome. +1 As regards the second part of you statement I think the size of the world population makes little if any difference to this stark fact. Have you come across the doctrines of Schumaker (Small is Beautiful) and Allaby (Limits to Growth) ? https://en.wikipedia.org/wiki/Small_Is_Beautiful http://www.herinst.org/envcontext/limits/writings/ecologist.html They are very attractive to well balanced, well motivated human beings. The only real drawbacks to these doctrines is that thay have no answer to threats from so called 'Military-Industrial' societies.

Your mechanical base variables can't be for instance time, velocity and acceleration. There would be one 'missing' variable in your set of 3. In fluid mechanics force, length and time are often used instead of mass, length and time.

I really don't see why either of these wild assed guesses (the other being that nonsence about gravity and heat) have not been move to speculations where they undoubtedly belong. They are most certainly not in accord with Physics theory, modern or classical. What do you mean by an electrical circuit ? Do you mean a complete loop or the more colloquial use of the word circuit as an assembly of electrical components ? Whilst it is conceivable that there could be an electron beam connection between the Earth and the Moon - like a giant cathode ray tube - I think that to well beyond our present technology. There is no natural process to achieve the same effect available, although we do receive natural charged particles from the Sun.

I know you can write more than repeating you first very short question. This one sided communication is becoming very tiresome.

No idea what you mean by this ?

For a single variable, yes. But you can't pick any old set of variables to fill your quota.

Even then it may still be fiction, depending upon how it is derived. Good points +1

A very complicated question. They allow dual Which makes things even more complicated. For one thing the Dutch still have a form of (military) conscription. For another they have an annual wealth tax. But they do not have inheritance tax.

I agree that there are a great many individuals in the world that feel powerles by themselves and actualy resentful of the fact that the literally can't make a different whatever they do. I certainly feel like that. This is especially sad since the totality of such folk is probably actually what is often referred to as "the silent majority". Our society actively promotes greed on a massive scale and this, combined with beaurocratic obstructionism and downright fraudlent secretism and (mis)use of public resources for private gain. 1% or 4% ? Well I suspect the scandalous cover up of Drax has much to do with it. is Drax bio friendly or very very bio unfriendly ? I sympathise with the planning refusal, especially as 6000 solar cells for the whole of your company's requirements, would not be so vey many. We have larger solar farms in the south west already. But there is currently an argument from objectors to a new one, because standard application practice has become to simply show the panel array and not mention the complex of ugly battery housing containers that are necessary to make the project viable. Yet this is nothing compared to the way the state supports new 90% of the oil drilling finances in the North Sea, whilst offering exactly zero support for solar and wind alternatives, unless they service a tax deductable drilling platform. I was shocked to learn this - source a recent BBC Countryfile investigation.

It doesn't usually rain organic solvents. To add to what exchemist said and what you may be thinking about. Plastics do not take part in many acid - base or redox reactions in normal environmental conditions. This is unlike many other materials, from wood to metals to soils etc. This is why the are considered less reactive but as has been pointed out in the right environment they are every bit as reactive.

In case you think this is purely academic showing off, here is a practical use of the cotangent, much used in cartography and surveying. https://en.wikipedia.org/wiki/Tienstra_formula

Here is a section of questions from an old trig textbook, involving the use of the secant, cosecant and cotangent. If you look in tables of standard integrals you will find these fromulae employed to solve the integrals, as swansont says.