Your question is the wrong way round. The concept of gravity being the force that makes apples fall is ancient. Before Newton, we knew that gravity makes the apple fall, but we didn't know what held the earth, moon and sun in a stable system.

What Newton did was to extend idea of gravity to the heavens. He did this by realising, and then mathematically proving, that the thing making apples fall is the same thing that holds the sun, moon and earth in a system.

This is what it was called 'universal gravitation'.

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Yup, you got it.

My previous answer is technically incorrect in the sense that "objects" at light speed don't really experience time anymore, but people have a tendency to ignore that bit when trying to explain relativity in hypothetical examples.

I think your answer is good for speech but it is overly specific.

OP asked about language, this answer is only about speech.

There are good theoretical arguments that the first languages were in fact sign languages (the gesture-first hypthesis) https://link.springer.com/article/10.3758/s13423-016-1117-3 . This article is quite accessible and lists some of the main arguments for it (while ultimately coming to a conclusion that the author things they arrose at the same time).

One argument I remember but that that article didn't mention was the benefits of gesture during hunts and ambushes though, co-ordinating these with spoken language doesn't work all that well unless the hunter is already afoot. And we do see hunter gatherer societies with sign languages (or rather, it is the same language using sign) today still.

Other arguments that are in the article include primates already existing gestural systems, as well as the ability and capacity to teach them some symbolic gestures from sign languages (no, koko did not 'know sign language', but she did know some signs).

As we see this in our modern primate cousins, a greater affinity for signed languages as compared to complex vocalisations, I'd ask why would our ancestors be different? Given the advantages to signed languages at particular times, the developing hand and tool manipulation skills our ancesters were fostering, and the likely already existing gestural system, I'd agree that the gesture-first hypothesis is at least plausible.

Tectonic and volcanic activity are caused by processes in the crust and mantle. Though the mantle very slowly flows and deforms like tar or putty, it is overwhelmingly solid (albeit very hot) rock. Magma exists only in certain regions of the crust and mantle, and even then mostly as a partial melt in a solid matrix, like water in a sponge, or slush.

The core does provide some heat from below, which helps power that activity, in addition to the heat in the mantle leftover form Earth's formation, and the heat in the mantle and crust generated by radioactive decay. But the core is not directly involved, and it being solid or liquid (it is both, actually, with a solid inner core and molten outer core) wouldn't necessarily preclude or permit volcanic or tectonic activity.

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And that the same force from the Earth was pulling on the moon. His was a theory of universal gravitation. Universal is the important idea.

Awesome! Thanks for the answer

One tangent worth noting in this context - it doesn't really affect the surface temp generally, but there are places where the heat of the inner earth does escape to the surface, and in these places they typically use it to have geothermal energy. Iceland has lots of cheap energy for this reason.

To elaborate. Aristotle believed that the earth element strove to be at the centre of the universe, water strove to be above earth, air above water, and fire above air. There was no concept of a force pulling everything together as in Newtonian physics.

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This is the most mind bendy thing ever! Is it because of some reason we know or is it because, well, it is!!?!!

Also, at what speed does the non-additive-ness start?

Fossilization is strictly the process where minerals have replaced tissue and bone, so as long as mineralization doesn’t happen you could have a bone as old as you want. It’s just hard to find them in nature because bone and tissue decays unlike minerals unless something like amber is involved.

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Oh wow thanks! I always wondered why the natural state of stuff was considered near the ground...

Newton formally linked the ideas of mass, acceleration, and weight, as well as the idea that weight and force are the same thing, and also linked force to the idea of changing momentum. He did all of this within a unifying theory of mathematics that relied on his fancy new tool that we would call calculus.

Now, there were other scholars in his day that had achieved bits and pieces of this already, but he brought it all together under a single unifying scheme and added significant portions of mathematical analysis to it (that allowed us to make novel predictions about the world and other worlds), so he's the one we remember. (It also helps his fame in the Western world that he wrote it in Latin, which was the scholarly gold standard of the day)

But the truth is we more or less understood how gravity works (mechanically, that is) since roman times, and newton didn't answer the "why" for us really anyway. What Newton really did was give us a formal mathematic definition of gravity that could be applied robustly to most physical situations humans can observe under one very large tent of mathematics. He allowed us to agnostically apply one set of laws to a whole host of situations that were not obviously connected. This, more than anything else, was his contribution to science.

It doesn't. That's just an outdated, incorrect idea.

Fast moving charged particles from the solar wind colliding with the upper atmosphere can gradually strip away some of the atmosphere through a process called sputtering. Magnetic fields shield from and redirect charged particles, so they can reduce this type of atmospheric loss (but planetary magnetic fields also contribute to atmospheric loss in other ways).

The motion (from convection and rotation) of the electrically conducting molten iron in Earth's outer core generates a magnetic field around the planet. Because this magnetic field is generated within the planet, it is described as an intrinsic magnetic field. The idea was that this is required to prevent the solar wind from stripping away the atmosphere.

However, Venus has a very thick atmosphere, and being closer to the Sun is subjected to a stronger solar wind than Earth. Yet, Venus lacks an intrinsic magnetic field (likely because its core, while molten, is not convecting). Because it lacks an intrinsic magnetic field, the upper atmosphere is exposed to the solar wind and its magnetic field, which induces a weak magnetic field in Venus' upper atmosphere. This induced magnetic field in turn protects the atmosphere from sputtering escape more or less like the intrinsic magnetic field would. The induced magnetosphere is not unique to Venus. Any atmosphere, be it Venus', Mars', or a comet's, exposed to the solar wind will develop an induced magnetic field. As such, atmospheric loss from sputtering is relatively insignificant for not only Earth with its intrinsic magnetic field, but for Venus and Mars as well.

What matters more for the ability to retain an atmosphere is ultimately the balance of a planet's gravity against the motions of gas particles caused by uncharged solar radiation, that is light, which is not shielded by magnetic fields. If the energy from sunlight causes the gas particles to reach escape velocity, they are lost to space. This is thermal escape, and encompasses a number of different processes.

Of particular relevance to Mars, ultraviolet light from the Sun breaks apart CO2 and water vapor molecules, producing ions which move faster than Mars' relatively low escape velocity. Venus and Earth have much higher gravity, so have been more able to hold onto their CO2/oxygen and nitrogen atmospheres. (Although at present, Mars isn't losing its atmosphere much faster than Earth or Venus are. It must have lost atmosphere emuch more rapidly in the past, particularly because the younger Sun would have emitted more UV radiation.)

As it is, though, Venus has lost almost all of its surface/atmospheric water because of solar UV and hydrogen escape. The runaway greenhouse effect it experienced evaporated/boiled any oceans, putting the H2O in the atmosphere where it could be broken up into hydrogen and OH/oxygen. Because hydrogen is so light, it is much more easily lost from the atmosphere to thermal escape than heavier gases like nitrogen, oxygen, or CO2.

Really interesting, thanks!

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It's important to note that Newton also defined the modern concept of 'Force'. The concept does not appear in preNewton works.

If you get too close to the wrong black hole then you become its accretion disk...

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