[AndroidNeox]

Wouldn’t it be equally reasonable to argue that things fall in the direction in which the strength of the gravitational field increases? 

The problem with attributing the acceleration to a change in field strength is that the rate of acceleration is not related to the rate of change of field strength. Any causal relation will probably have a fixed relationship.

[Bill S]

The problem with attributing the acceleration to a change in field strength is that the rate of acceleration is not related to the rate of change of field strength.

Perhaps I could ask three naïve questions:

1. Disregarding any changes in strength; does the gravitational field cause the acceleration?

2. What might influence the rate of acceleration?

3. Was Rovelli talking about changes in the rate of acceleration when he said: “Things fall downwards because, down there, time is slowed by the Earth.”?

[yor_on]

I'm not sure how he reaches that conclusion Bill. In Einsteins terms the thing 'falling' is in a geodesic. The geodesic defined by mass (and 'energy'). It's not even 'accelerating' as it falls, it's in a uniform motion as can be proven if we exchange the 'thing' for a free falling parachutist. The whole idea of fast and slow time goes out from a global conceptual view of the universe, with no proof existing from a local point of view. According to your wristwatch your time rate never change, if it did there would be no standard for defining other frames of reference.

[yor_on]

Well, he might think of in terms of what I wrote about it being a 'uniform motion' aka 'weightlessness', then stating that the only thing that change is this conceptual global time as you get closer to Earth. It is a correct interpretation presuming that you then define different 'timezones' depending not only on mass (energy), but also accelerations and 'speeds'. What makes it so dubious is that it takes away any 'golden standard' of time rate for the local observer. You can no longer compare other frames of reference, presuming your clock to be a 'proper time', as you have no standard for what is a proper time. I guess you could treat it similar to Lorentz transformations possibly, and so gain some idea of what then would be your local 'clock rate', at that time and place, but there would still only be a arbitrarily made time as there is no standard except 'proper time', which you then must invalidate to gain that perspective.
=

Proper time is the time (wrist watch) you use to define other frames 'time rate' from. The idea behind it is that this is the simplest way to gain a standard of sorts. It's what we use to define a repeatable experiment by f. ex. Putting that into question you will find yourself in all kind of difficulties defining anything. It's a lot simpler to use 'proper time' than to think of yourself as being in 'slow'/'fast' time, especially as it also will be observer dependent depending on someones uniform motion relative yours. That means that 'proper time' in a black box scenario won't exist, as there is no way for you to (locally) define your relative motion inside that box. So I would avoid that interpretation if I was you :)

Allowing someone else to define your relative motion, calling you to tell you what 'speed' he found for you doesn't help either. His definition will be dependent on his frame of reference, aka 'observer dependent' too.
=

Let me see if I can clarify the way I look at it a little more. As far as I know your relative motion has nothing to do with the outcome of a repeatable experiment, done inside a so called 'black box'. And that hopefully puts the way I define the idea of 'proper time' in a sharper focus. But if you want 'slow' and 'fast' time to be locally, there can't be a 'proper time', as uniform motions also creates ' time dilation's ', just as accelerations.

[Bill S]

Having looked briefly at the context of Rovelli's statement, I suspect we are over thinking this one; but what are science discussion forums for? 

[yor_on]

Yes, we probably did, the last part is sufficient for destroying any idea of slow and fast time , locally defined. If a 'repeatable experiment' don't care about relative motion, then 'proper time' is more than just 'relative'. the only way to disprove that would be to prove that only accelerations can give a 'time dilation'.

[yor_on]

It's 'curved space' that defines orbits etc, according to relativity. That origins from mass/energy. There is no 'attraction' in the sense of magnets acting upon each other through some EM field. But there is a equivalence in that mass act upon mass through this 'curved space'.

[Bill S]

It's 'curved space' that defines orbits etc, according to relativity.

That's another example of a "short-hand" term that can easily cause mistaken thinking among us "hitch-hikers".

The term is fine, as long as we remember that gravity is a force that is more completely described by spacetime curvature and not Newton's law.   

[yor_on]

yes, i also find problems with what to use there. But the end result is that the way 'space' is 'folded' define the paths of  ' heavenly body's '' which in their turn then define the way 'space folds', making those 'paths'. Seems to me as a merry go round that one :) . If you like a added complication you just need to consider that all uniform motions, from a 'black box example' are equivalent, no matter their (relative) speeds.

[Professor Mega-Mind]

..................News Flash !
 It appears that N. Harimae has conclusively shown that that the N. strong force is gravitational .  That is , it is actually gravity , caused by the immense mass-density of the proton itself .  This concentration of mass/energy is also identical to a same-sized black hole .  This throws a spotlight on just how unimaginably strong the bonds controlling/connecting the substance of space really are .  As  all radiation/particles are made of  the substance of space (but energized) , the connection must be nascent .  It appears to be activated (pulled upon) by the introduction of energy/potential-energy to the space in question . If  there is no real matter , only energy  being transferred around by conductive space , that means that   only the patterns are real , the rest is appearance , like holograms of reality .  Apparently , a higher density of space-substance makes for slower , more massive ,  energy transmission .  Lower S-density necessarily makes for faster , less massive , energy transmission .  This explains the relative cosmic speed-limit , and also illuminates a new avenue , for investigating the composition of the substance of space itself .  Dark Matter would be an excellent place to begin , uni-directional gravity does not come easily !
P.M.

[evan_au]

It appears that N. Harimae has conclusively shown that that the N. strong force is gravitational .

The strength of the electric field of a proton to an electron (or to another proton) is enormously greater than the strength of the gravitational force between them.

The Strong nuclear force is even stronger than the electric field (in the short range of distances over which the strong nuclear force operates).
- Since the Strong Nuclear force has a finite range (about the width of a Uranium nucleus), while the range of the gravitational  force is infinite, how can you construct the Strong Nuclear force from the Gravitational force?

[Professor Mega-Mind]

..................Translation
That transition/translation is why he is the world-famous physicist , not I .  You , perhaps , are better able to examine his work , from a hard-tack , formulaic standpoint . 
  I await with baited breath .
P.M.

[Kryptid]

 It appears that N. Harimae has conclusively shown that that the N. strong force is gravitational .  That is , it is actually gravity , caused by the immense mass-density of the proton itself . 

If that was true, then (1) the strong nuclear force should affect all subatomic particles (since all particles have mass-energy, which is what produces gravitational fields), (2) the strength of the strong nuclear force should scale linearly with the mass of the particle, and (3) the strong nuclear force should have an infinite range with a strength that falls off with the inverse square of the distance. None of these cases are true in reality. The Tau lepton is about 1.9 times heavier than the proton but doesn't interact with the strong nuclear force at all. The strong nuclear force also falls off in strength much faster than gravity does with distance (so much so that it is practically non-existent outside of nucleus-level distances).

[Professor Mega-Mind]

...............Gravito-metrics .
I believe his conclusion is that the expression of gravity is different for different forces .  That is ; the range and rate of decrease , varies for each one .  It is analogous to different wavelengths for different colors .
P.M.
 

[Kryptid]

I believe his conclusion is that the expression of gravity is different for different forces .

Given that gravity is a force itself, this sentence makes no sense.

Also, who is this N. Harimae person? I can find no relevant hits on Google when I type in that name.

[Professor Mega-Mind]

..............Nassim Haramein
Featured in :                                     
     "The Connected Universe"
Proponent of alternate sub-atomic physics and dynamics .
D.H.

[Kryptid]

I wouldn't take what he says too seriously. His hypotheses have not appeared in peer-reviewed journals and it's easy to point out the flaws in them:

https://rationalwiki.org/wiki/Nassim_Haramein
https://azureworld.blogspot.com/2010/02/nassim-haramein-fraud-or-sage-part-2.html

[Professor Mega-Mind]

Unconventional , outside the box , views tend to garner skepticism , not acceptance .  The concept of one basic force , with multiple facets (expressions) , seems more natural to me .  Alternate views do sometimes lead to new , clearer understandings of things .
P.M.

[Kryptid]

Unconventional , outside the box , views tend to garner skepticism , not acceptance .

My skepticism isn't because the idea is unconventional, it's because it goes against the evidence. The strong nuclear force doesn't follow the same rules as gravity.

The concept of one basic force , with multiple facets (expressions) , seems more natural to me .

It seems natural to physicists too, as mainstream unified field theories say the same thing (the underlying mechanics differing from one to the other).

[Professor Mega-Mind]

In a sense , it's all attraction of energy to itself .  The counter-balance is the pressure of saturation . 
P.M.