They fall because there is nothing to hold them up
Nothing holding them up does not provide a reason for them to fall.
You would still need an actual reason.
Is there anything holding them down? If not, why don't they fly up?
You need an explanation for the directionality.
BECAUSE they were lifted. Things fall with the energy that was used to lift them - nothing more; in accordance with the law of conservation.
Yes, just like if I push this glass sitting on my desk to the right, expending energy to do so, it falls back to the left. Oh wait, it didn't.
Maybe the friction of the table got in the way. I'll try with throwing a ball to the right. Surely that should then force it back to the left.
Strange, still no. It is as if that explanation is pure nonsense which doesn't explain it at all.
We clearly have examples of expending energy to move an object, yet it doesn't cause it to go back the other way.
So that clearly doesn't explain it.
You need an explanation for the direction.
Why does lifting an object take energy, where you supply the object with gravitational potential energy (I suppose you would call it weight potential energy?) But only lifting it, with moving it to the side not taking that energy?
Why does it then release this energy when it comes back down. Just what is this energy in your "weight makes things go down"?
In fact, without something like gravity, the simple act of throwing a ball up into the air and having it fall is a direct violation of the law of conversation of energy.
If it conserved energy it would continue moving upwards, rather than losing energy for no reason at all. And when stopped it would not accelerate downwards as that would give it energy from nothing.
Knowledge is a subset of belief.
I like it, it is poetic - it's just wrong.
I don't care if you want to reject it, it is still true.
A belief is something you think is true.
Belief are the things you think are true.
Knowledge are those things you think are true, that actually are true, and that you have a justification for thinking are true.
What you are thinking of is faith.
I say he wasn't a scientist because he wasn't - not in the modern sense of the word we use today.
How wasn't he?
Gravity was NOT his idea
So whose was it?
Especially with it being a universal law of gravitation, with F=GMm/r^2
He speculated a cause, called gravity. He did not even bother, famously, to even feign a hypothesis regarding it
So what was the whole F=GMm/r^2 thing?
That sure seems to be a hypothesis.
The only question is how to test it.
We already knew Earth was massive, and thus the force acting on an object on Earth would be quite small, and thus hard to actually test the law.
But we have gotten a lot better since then, and have validated it in the low energy limit.
No, it isn't.
The evidence for gravity is used as the evidence for UA.
Again, A TINY PORTION of the evidence for gravity is used for UA. (that things fall)
They 2 are not simply equivalent in the sense of you can just reject gravity and replace it entirely with UA.
They are equivalent in a local environment, where for a given local environment, where the gravitational acceleration is constant, that can be equally explained with gravity or acceleration.
But in a much broader sense, it can't. That is because the gravitational acceleration changes.
Again, for a simple example, with accepting the fact that Earth is round (which you can do for the sake of argument even if you don't accept it):
UA postulates that Earth accelerates upwards instead of gravity pulling us down. But with a round Earth this would be Earth accelerates outwards. This would mean that it would grow over time, drastically increasing its size and isolating parts of Earth from other parts in short order.
It would also mean that a satellite wouldn't maintain an orbit. Again, the simple way is that Earth would expand outwards and it would crash into it (as it follows a straight line). The more complex way is to note that to maintain the orbit the average of gravity needs to be 0, that is the direction changes such that after some period of time the total acceleration amounts to 0. For UA this would actually require Earth to be going around in circles around a stationary satellite. And that would have to apply for each satellite.
Likewise it in no way addresses cavendish.
You cannot simply reject gravity and replace it with UA, it simply doesn't work.
Just like you can't simply reject gravity and replace it with weight magically falling for no reason.
I am confused by the phrasing, could you restate?
UA is almost, but not quite, universal.
It seems to act to accelerate almost everything, the Earth, the moon, the sun, and all the other stars and celestial objects.
But for things just above Earth, it doesn't. Instead they are only indirectly accelerated by Earth. This means a ball just above Earth when released appears to fall and hit Earth, while the sun, much higher above (but still quite low compared to the size of Earth) is accelerated upwards and thus doesn't appear to fall and hit Earth.
And these objects which are accelerated upwards are all accelerated up at the same rate, so they aren't separated or fall smashed together; even though they have vastly different sizes.
This raises serious questions for how all that is achieved and makes UA extremely complicated.
I think that is a valid criticism/question, however it is easily reconciled if one is so inclined. For instance, there are those that conclude that the apparent acceleration variance is caused by other factors (like varying buoyant force, seismic activity, etc.) and so on.
And they can all be ruled out.
Buoyant force would have no effect in a vacuum chamber, or when the environment is controlled to make it the same. The accurate gravimeters use a ball falling in a vacuum.
Seismic activity would only work to explain fluctuations, not sustained variations, unless that seismic activity is Earth being torn apart.
So neither of those explain it.
Instead you would need to appeal to some other force like gravity, or claim the UA somehow penetrates Earth and acts on things, but only slightly (yet still manages to then accelerate things much higher, and raises the question of why that doesn't on the size of the object).
So we are told, yes! In any case, the point was that no technology or science requires the shape of the earth to be anything particular.
And he specifically referred to a smartphone, which uses GPS. Not to mention it also has a clock (which keeps time accurately using GPS), which is based quite heavily on the shape of Earth, as a RE can actually explain different time zones and things like the sun setting.
If Earth was flat, we would have a vastly different time setup.