# Does this explain what generates gravity?

#### system7

Da Vinci was interested in Art and Science. And had been instructed in the Mathematics of the time, which often involved Platonic solids.

But there's an error in that article which even a Child of Ten would spot.

The team interpreted tick marks on da Vinci’s sketches as data points the polymath made based on his eyeballing of the experiment in action. In lieu of a timepiece, da Vinci found the gravitational constant to nearly 98% accuracy.

Certain things can be calculated from watching a jet of water going sideways, presumably a parabola, but NOT the Gravitational Constant!

https://en.wikipedia.org/wiki/Gravitational_constant

For that, you need to know the mass and radius of the Earth. And a clock.

Now, the acceleration of Earth's gravity in some sense I might believe! 32 feet per second per second in old units.

A good artist needs a bit of mathematics to get perspective drawing credible. I think Giotto was the man who formalised it around 1300:

https://en.wikipedia.org/wiki/Giotto

But it is interesting that all the great Scientific Renaissance figures were interested in Astronomy and Mathematics, and very acute and precise observers.

For sure, by 1500, most of the smart people believed the Sun was the centre of the Universe. Heliocentric. The word had gone round.

The Catholic church didn't like the radical new ideas....

https://en.wikipedia.org/wiki/Nicolaus_Copernicus

Galileo and Kepler were the next great unravellers of things in the Solar System, and actually beyond, around 1600.

And then Newton. Who discovered the Gravitational Constant around 1680. Though he didn't know exactly what it was, since he could only guess what the Earth's mass is.

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#### Galu

Certain things can be calculated from watching a jet of water going sideways, presumably a parabola, but NOT the Gravitational Constant!

Yes, Leonardo wouldn't even have been able to calculate the gravitational acceleration (g), let alone the gravitational constant (G).

He was unaware that the vertical displacement (s) of a falling object is directly proportional to the square of the time (t) - as in the equation s = 1/2 g t^2

Da Vinci did design an accurate clock in his lifetime. Unfortunately it only showed hours and minutes, and not seconds.

https://www.da-vinci-inventions.com/clock#:~:text=To put away any initial confusion – Leonardo,incorporation of the pendulum about 200 years later.

#### system7

I was wading through the long-forgotten Algebra of Leonardo's very complicated apparatus to measure "g". The maths is schoolkid's O -Level.

https://en.wikipedia.org/wiki/Equations_for_a_falling_body

However you do it, you need either an accurate way of measuring speed, Or an accurate stopwatch. I don't think he had either.

I was surprised how good clocks were even around 1300.

https://en.wikipedia.org/wiki/Clock

But not for the second scale. Perhaps Leonardo had glimpsed something about a Parabola in falling bodies. The 45 degree slope at a certain juncture.

Galileo was THE MAN! He timed things over known distances.

Galileo was the first to demonstrate and then formulate these equations. He used a ramp to study rolling balls, the ramp slowing the acceleration enough to measure the time taken for the ball to roll a known distance. He measured elapsed time with a water clock, using an "extremely accurate balance" to measure the amount of water.

Really don't want to spend any more time on this. More junk science IMO!

I am reading more useful stuff apropos Special and General Relativity. And hopefully avoiding The Quantum for now.

Excellent 1995 primer on General Relativity, Black Holes and all that. Not too techy, but a bit of simple maths.

Learning lots of surprising things. Very good explanation of the twin paradox in Special Relativity.

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#### Galu

I was wading through the long-forgotten Algebra of Leonardo's very complicated apparatus to measure "g".

Don't you mean Galileo?

#### system7

I know exactly what I meant. Leonardo's complicated looking problem!

https://gizmodo.com/leonardo-da-vinci-gravity-sketches-experiments-1850123741

y = - 1/2 g t^2

x = v t

Differentiate wrt t:

dy/dt = - g t

dx/dt = v

At the 45 degree slope point and time of the parabola, dy/dx = -1

Therefore g = v / t

or g = x / t^2 or g= v^2 / x.

It's actually the projectile problem.

https://en.wikipedia.org/wiki/Range_of_a_projectile

To get maximum range d max from a gun, you set it at 45 degrees. The distance the cannonball or shell goes is:

d max = v^2 / g ( Where v is muzzle velocity.)

Ignoring air resistance. QED.

#### Galu

I know exactly what I meant. Leonardo's complicated looking problem!

But Leonardo didn't set out to measure g like you said, hence my request for clarification.

As an expert on gravity, don't expect me to fall for any old tat!

#### system7

I am not wasting any more time on this!

Spurious claim:

The team interpreted tick marks on da Vinci’s sketches as data points the polymath made based on his eyeballing of the experiment in action. In lieu of a timepiece, da Vinci found the gravitational constant to nearly 98% accuracy.

https://gizmodo.com/leonardo-da-vinci-gravity-sketches-experiments-1850123741

These people are idiots. Now having observed the conjunction tonight, I must get back to my proper Physics book and Tony Blacburn's Golden Hour on Radio 2.

#### benb

I was wading through the long-forgotten Algebra of Leonardo's very complicated apparatus to measure "g". The maths is schoolkid's O -Level.

https://en.wikipedia.org/wiki/Equations_for_a_falling_body

However you do it, you need either an accurate way of measuring speed, Or an accurate stopwatch. I don't think he had either.
Probably the best he had was his pulse/heartbeat, which (I first read elsewhere many years ago) is what Galileo used when observing ...
In 1581, when he was studying medicine, he noticed a swinging chandelier, which air currents shifted about to swing in larger and smaller arcs. To him, it seemed, by comparison with his heartbeat, that the chandelier took the same amount of time to swing back and forth, no matter how far it was swinging.
https://en.wikipedia.org/wiki/Galileo_Galilei#Career_as_a_scientist
I was surprised how good clocks were even around 1300.

https://en.wikipedia.org/wiki/Clock
The article mentions of John Harrison (I remember his name by thinking of two Beatles), a legendary clockmaker about whom much has been written (such as the popular book "Longitude" by Dava Sobel). This video is quite interesting (except, IMHO, the part where the narrator tries to make his own clock, feel free to skip it):
https://www.theguardian.com/science...n-harrison-vindicated-250-years-absurd-claims
I may have posted this info in a previous thread - all this was delightful reading for me.

#### system7

My dear departed brother, Clive, was interested in anything old or antique.

He liked climbing the dark and dusty towers of old churches and taking photos of the clocks.

His most famous horological work currently fetches £80 for a first edition on eBay:

He gave us all a copy for Christmas. After all, there is no present like the time!

I lost my copy years ago! I found it a bit boring, myself... seen one clock, you seen em' all, IMO.

https://en.wikipedia.org/wiki/Salisbury_Cathedral_clock

It seems that around 1300AD, clocks used a rotating or oscillating thingie on a spiral spring, called a verge and foliot escapement:

https://en.wikipedia.org/wiki/Verge_escapement

Then about 1600, clocks started to use pendulums, following Galileo's discovery of them:

Seems John Harrison's Marine Chronometer of 1730 used the older rotating mechanism, which makes sense, because a pendulum wouldn't work too well on a rolling ship.

Hope that clears it up.

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#### Galu

I bought my first watch on tick!

#### Galu

Unfortunately, Dave, the 'Giant Arc' of galaxies has been illustrated by pictures of the Milky Way!

I believe this research, involving the analysis of light from distant quasars, coincides with the search for the filaments of dark matter which connect galaxies and galactic clusters together like a vast, cosmic web.

I mentioned the cosmic web earlier and here is the link to the research: https://www.sciencealert.com/strand...ve-been-revealed-in-groundbreaking-new-images

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• Simulation of the Cosmic Web.jpg
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#### cumbb

Unfortunately, Dave, the 'Giant Arc' of galaxies has been illustrated by pictures of the Milky Way!

I believe this research, involving the analysis of light from distant quasars, coincides with the search for the filaments of dark matter which connect galaxies and galactic clusters together like a vast, cosmic web.

I mentioned the cosmic web earlier and here is the link to the research: https://www.sciencealert.com/strand...ve-been-revealed-in-groundbreaking-new-images
From the article: "Although the Universe is a large place, and all the stuff in it may seem just flung everywhere higgledy-piggledy, there's rather more structure than we can see.
According to our models of the Universe, and mounting evidence, filaments of dark matter connect massive objects such as galaxies and galaxy clusters in a vast, cosmic web."

"Filaments of dark matter" or e.g. magnetism, electromagnetism?

#### cumbb

From article: "This paper suggests that no "expanding background" is necessary for gravitons to produce photons, and for these particles to then interact to form mass. Not only does this add a further doubt to the validity of the Big Bang but it says we need to revise the current understanding of the Higgs field and its boson. By introducing a novel Vector-Tensor-Scalar (VTS) Geometry, we assign a scalar value to the Higgs and explain its origin from graviton-photon interaction. VTS Geometry can then be used to explain dark matter and dark energy through the use of Wick rotation and quaternions. I gratefully acknowledge the equational contributions of Alessandro Rizzo. His expertise was instrumental in the equational aspects of this work. However, his involvement does not imply endorsement of the theoretical propositions presented."

At least they have already removed "expanding background". Still missing - article: " Higgs boson, Graviton-photon interaction, Dark energy, Wick rotation, Quaternions, Quantum Field Theory" and more. All these theses are based on circular reasoning, incomplete descriptions, misdescriptions, misinterpretations.
... and on arbitrary introduction of arbitrary "constants" in their arbitrary "mathematics"-)

The "one theory" would be feasible at present only on a conceptual, thought, level: for instance "different/relative"-)

#### abstract

I still prefer phonons.
Ever notice the drastic difference between a slow golf-clap and a more enthusiastic clap? With increasing speed there's a rather sudden transition from a soft patter to a loud crack, which doesn't seem to make sense, unless there's something highly non-linear happening.

Also, I like the idea of physical acceleration due to growth. So, estimating gravity of large objects based purely on diameter seems to give surprisingly good results, with only minor corrections needed for electrostatic charge.

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#### cumbb

"estimating gravity of large objects based purely on diameter"
But does not explain gravitation: Maybe "gravitation" is also a "phanomenon" of "electrophysics" - as we do not see, understand it yet.

#### Galu

I just knew those pesky "quaternions" would rear their ugly heads at some point!

They've been lurking around since 1843 just waiting for the opportunity to explain dark matter and dark energy.

Quaternions have 4 dimensions , one real dimension and 3 imaginary dimensions. Each of these imaginary dimensions has a unit value of the square root of -1, but they are different square roots of -1 all mutually perpendicular to each other, known as i, j and k. So a quaternion can be represented as follows: a + i b + j c + k d

But chuck in a "Wick rotation", and we're all likely to get dizzy!

The Wick rotation is used in Euclidean quantum gravity to describe the force of gravity according to the principles of quantum mechanics. In short, it's a mathematical trick which uses imaginary numbers to simplify certain formulae in physics. So there you go!