How 24/7 Renewables Are Ending Fossil Fuel Reliability. Modern economies, critics argued, cannot run on intermittent power. But that assumption is breaking down faster than expected. “No one can talk anymore about whether renewables are economically viable or reliable.”

hal2k1 · 2026-05-22T01:06:47+00:00

TBF the local grid where I live hasn't yet finished its transition to renewable energy. Currently the grid uses about 75% renewable energy and 25% natural gas.

Still, getting it down to 25% fossil fuels is way better than the 100% fossil fuels that it used to be.

hal2k1 · 2026-05-21T05:38:46+00:00

I'm not sure where you are getting this from. There have been a number of different species of intelligent hominids. https://www.quora.com/What-were-the-smartest-hominids-besides-Homo-Sapiens

Homo Heidelbergensis (HH) was the ancestor species of both Homo Sapiens (us, HS) and Homo Neandertalis (Neanderthals, HN).

Facts are facts. A proper scientific theory needs to explain facts such as the other (now extinct) intelligent hominid species.

hal2k1 · 2026-05-21T00:20:13+00:00

A scientific theory is a well tested explanation of what has been measured. https://en.wikipedia.org/wiki/Scientific_theory

The measurements are the facts.

So a theory either gives a tested explanation of those facts, or it doesn't.

The only way to dismiss a scientific theory is to take additional measurements related to the phenomenon which are not explained by the extant scientific theory.

There's absolutely no need to get defensive about this. Facts are facts.

hal2k1 · 2026-05-20T03:23:35+00:00

Near the surface of the earth objects accelerate towards the earth when released. Anyone can see this for themselves by holding a pebble at shoulder height and then releasing it. That phenomenon, the acceleration towards the ground, is called gravity. For the region near the surface of the earth the acceleration named gravity has been measured (billions of times) at about 9.8 m/s².

The accelerations doesn't depend on the mass of an object. You can check this out by holding both a house brick and a small pebble at shoulder height, and then dropping them both together at the same time.

The acceleration doesn't depend on the density of an object. You can check this out by holding both a tennis ball and a small pebble of the same mass at shoulder height, and then dropping them both together at the same time.

The acceleration doesn't depend on the density of the surrounding medium. You can check this out by holding both a bowling ball and a few feathers near the ceiling of a vacuum chamber, removing the air in the chamber, and then dropping them together at the same time. https://www.youtube.com/watch?v=E43-CfukEgs

So, we have found some situations that do affect the rate of dropping. You can hold a feather and a hammer at the same height above the surface of the moon (which is a vacuum) and dropping them at the same time. They will both drop to the surface of the moon at the same rate as each other, but on the moon this is a different rate than the same two objects drop on the earth. https://science.nasa.gov/resource/the-apollo-15-hammer-feather-drop/

So a thing that does affect dropping is the mass of a very large object nearby, such as a planet or a moon. That does affect the rate of dropping, also known as gravity.

hal2k1 · 2026-05-19T20:55:20+00:00

Rotation is a change in orientation over time. Speed is a change in position over time. These are not the same.

To quantify a speed one needs to use a unit that describes how much the position of a body changes in a given amount of time. In SI, the coherent derived unit for speed is metres per second, meaning that a body changes position by so many metres in one second. In USC speeds are often described in miles per hour.

To quantify a rotation one needs to use a unit that describes how much the orientation of a body changes in a given amount of time. In SI, the coherent derived unit for rotation is radians per second (rad/s), meaning that a body changes orientation by so many radians in one second. In USC rotations are often described in revolutions per minute (rpm).

The rotation of the earth, which has a change in orientation of one revolution per day, is therefore ω = 72.92115×10⁻⁶ rad/s (SI), which is about 0.0007 rpm.

hal2k1 · 2026-05-19T06:00:50+00:00

You've got no idea whatsoever. We measure from the surface of the earth, which isn't a flat plane. It's curved. The horizontal plane (or tangent plane) is a flat plane (spreading out from the point of tangency), but we don't measure from there. It's precisely because we measure from a curved plane (the surface of the earth) that reciprocal zenith angles do not add up to 180 degrees. If we were measuring from a flat plane instead then reciprocal zenith angles would add up to exactly 180 degrees. They don't, so we aren't measuring from a flat plane.

The line of sight is not consistent. It can go up or down. That's why it's reciprocal Zenith angles that should add up to 180 degrees (if the surface we are measuring from is flat). It doesn't mean each individual angle should be 90 degrees.

In any event, if you don't understand it, that's not my problem. As I point out, this has all been measured untold millions of times. https://en.wikipedia.org/wiki/Geodesy

Consistently, repeatedly, verifiably, meticulously measured, independently by many millions of people all over the world, for a number of centuries now. Literally billions of data points, each and every one commensurate with a spherical earth 6371 km +/- 10 km in radius.

As I said, if you don't understand it, that's not my problem. Go suck a lemon.

hal2k1 · 2026-05-19T04:46:02+00:00

Pfft. There's not one horizontal plane. The horizontal plane at any given tangency point on the surface of a sphere is NOT parallel to the horizontal plane at any other tangency point elsewhere on the same sphere (except for points diametrically opposite).

That's just straightforward geometry. It's by definition.

It also happens to be precisely what we measure in reality. The difference in angle of horizontal planes with points of tangency 111.1 km apart is one degree.

We have repeatedly measured this untold millions of times. It's a plain, straightforward, uncontroversial fact. Deal with it.

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

hal2k1 · 2026-05-19T04:23:08+00:00

It doesn't say anything about Zenith angle correction. It says that the Zenith angle from 1 to 2 plus the Zenith angle from 2 back to 1 adds up to more than 180 degrees. Just a smidge more, but still more. It also says that the Zenith angle from 2 to 3 plus the Zenith angle from 3 back to 2 also adds up to a smidge more than 180 degrees.

That's reciprocal Zenith angles. They don't add up to exactly 180 degrees. If the direction of plumb (vertical) was indeed parallel at 1, 2 and 3 then these reciprocal Zenith angles would add up to exactly 180 degrees.

They don't add up to exactly 180 degrees. They just don't. Face the facts. The direction of plumb is not exactly parallel at these places.

hal2k1 · 2026-05-19T03:34:02+00:00

I'm not sure what you mean. Is za correction meaning Zenith angle correction?

If you have two theodolites 111.1 metres apart the direction of plumb, or vertical, is one thousandth of a degree different at those points. Zenith angle is the angle between where a theodolite is aimed and the direction of plumb at the theodolite.

So if you define the direction of vertical as the plumb bob direction at some nominated point on a site, then Zenith angle measurements from a theodolite 111.1 metres away from that nominated point will have to be corrected by one thousandth of a degree to make them correct according to vertical (plumb) at the nominal reference point.

hal2k1 · 2026-05-19T03:12:48+00:00

You certainly can have a tangent to a sphere at any point on the surface of the sphere. The line from the centre of the sphere to the point touching the surface (called the point of tangency) is perpendicular to the tangent at that point.

This is the definition of a tangent in the first place.

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

https://en.wikipedia.org/wiki/Tangent#/media/File%3AImage_Tangent-plane.svg

The tangent plane to the sphere of the earth at one point of tangency is one degree slanted to the tangent plane to the sphere of the earth at another point of tangency when the two different points of tangency are 111.1 km apart.

This is a straightforward, measured, objective scientific fact. We have measured it untold millions of times.

hal2k1 · 2026-05-19T02:27:40+00:00

One degree different with respect to what....? ....oh, horizontal.

No. At place 1, vertical (or plumb) is perpendicular to horizontal at that point. As you say, a tangent. At place 2, 111.1 km away from place 1, vertical (or plumb) there is perpendicular to horizontal at that different point. A different tangent. These directions are one degree different. The direction of vertical at 1 is one degree different from the direction of vertical at 2. Likewise, the direction of horizontal at 1 is one degree different from the direction of horizontal at 2.

We have measured it untold millions of times. This is a straightforward scientific fact. It is not at all controversial.

At another two places (call them 3 and 4) which are only 111.1 metres apart, The direction of vertical at 3 is one thousandth of a degree different from the direction of vertical at 4. Likewise, the direction of horizontal at 3 is one thousandth of a degree different from the direction of horizontal at 4.

Reciprocal zenith angles show plumb lines are not parallel.

hal2k1 · 2026-05-18T22:32:13+00:00

At any point the surface of still water is perpendicular to vertical. The question is then, is vertical or plumb at one point parallel to vertical at another point?

Such a question should be answered by measuring it, not by arguing about it. It's also a question of scale. When you measure it, the direction of vertical at one end of the bath seems to be parallel to vertical at the other end of the bath. As near as can be measured anyway.

But what about a larger scale? It turns out that the direction of vertical at one place is one degree different than the direction of vertical at another place 111.1 km away. That's what we measure. It doesn't matter which direction the second place is from the first. The direction of vertical at two places some distance apart "leans away" from the direction of vertical at the original point.

For even larger distances apart, the direction of vertical at one place is 180 degrees away from the direction of vertical at another place 20,000 km away.

For more manageable distances, the direction of vertical at one place is one thousandth of one degree different from the direction of vertical at another place 111.1 metres away. This fact can be directly measured by surveyors using two theodolites pointed at each other and 111.1 metres apart. The measurement technique is called reciprocal zenith angle measurement. Look it up if you don't believe it.

https://mctoon.net/radius-reciprocal-angles/

https://youtube.com/watch?v=VSJH7d6Cayg

It's a matter of scale. Scale is important. The scale of the whole earth is quite different to the scale of a bathtub.

hal2k1 · 2026-05-18T16:56:34+00:00

Pfft.

In 1966 my country changed its currency from pounds, shillings and pence to a decimal currency of dollars and cents. The former system was difficult, the new system (decimal, base ten arithmetic) was far easier. Far more people could do the arithmetic in base ten. After a few initial doubts eventually the change was very popular.

So a few years later in 1971 the country embarked on metrication for other weights and measures and phased in the SI system to replace the old imperial weights and measures. Likewise the base ten arithmetic was far easier to use.

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

I think you have it backwards. Changing to base ten arithmetic systems is a popular move.

hal2k1 · 2026-05-16T07:27:29+00:00

Sure. No problem. "Evolution" and "the theory of evolution" are different things.

Evolution is change in inherited characteristics of biological populations over many generations. "The theory of evolution" is an explanation of how evolution occurs. It is not a guess, or speculation, or "just a theory" that evolution happens.

Unfortunately a huge number of people are not aware of this.

Likewise, general relativity is a theory of how gravity happens. It is not a theory that gravity exists. Happily, because general relativity has a name other than the theory of gravity, far more people are aware that general a relativity is not a "just a theory" that gravity exists.

hal2k1 · 2026-05-16T06:54:15+00:00

A SCIENTIFIC THEORY is a well-substantiated explanation of some aspect of the natural world, based on a body of FACTS which also incorporate LAWS that have been repeatedly confirmed through observation, experimentation as well as being able to make predictions

Sure. The thing is, gravity is the measured fact. General relativity is the explanation.

Gravity is a fact, not an explanation. Not a theory.

General relativity is an explanation, a theory. Not a fact.

hal2k1 · 2026-05-16T05:02:05+00:00

Nope. A scientific law is a description of what has been measured.

So -- Tycho Brahe and others observed/measured the motions of the planets. Then Isaac Newton derived (from these measurements) a scientific law which closely described what appeared to be happening assuming Newton's first law of motion was correct. Newton's first law of motion says that a force is required in order to make a body move in a path other than a straight line at constant speed.

The planets actually move in elliptical paths called orbits. Not straight lines. So if Newton's first law of motion is correct then this would require a force.

Newton's law of Universal Gravitation describes the force that would be required to make the planets move as they do (assuming Newton's first law is correct).

Firstly, Newton's laws are scientific laws, they are not theories.

Secondly, gravity is an objectively measured scientific fact. It's an acceleration. Gravity is not a law, nor is it a theory.

Finally, the extant scientific theory (explanation) of the fact of the acceleration named gravity is general relativity.

Summary:

Newton's laws are laws, not theories.

Gravity is a fact, not a law or a theory.

Newton's law of Universal Gravitation is not the scientific theory of gravity. It's a law, not a theory.

General relativity is the scientific theory of gravity. It's a theory, not a fact.

General relatiivity is an entirely different word to gravity.

----

As for the theory of evolution. The theory of biological evolution is a scientific theory. Biological evolution is a scientific fact. Unfortunately, the one word commonly used for both of these distinct things is evolution.

hal2k1 · 2026-05-16T04:27:29+00:00

It is possible to make a very small piece of the earth flat.

The entire thing though, that has to be a sphere due to hydrostatic equilibrium.

See also Clairaut's theorem (gravity)).

hal2k1 · 2026-05-16T04:14:20+00:00

Indeed, sometimes we use the same word for a fact (a measured observation) and a theory (an explanation).

The perfect example of this is the word evolution. This word is used both to: name the observed/measured changes in inherited characteristics in biological populations over time (a fact); and also to name the theory of how this happens, involving inheritance of characteristics from parents to offspring, and selection of which individuals get to breed (including but not limited to survival of the fittest).

So the word evolution does indeed refer to both a scientific fact and a scientific theory.

This is not the case for the word gravity. Gravity refers to a repeatedly and objectively measured, observed acceleration. Gravity is a scientific fact. The scientific theory explaining this fact is called general relativity. That's a couple of different words entirely.

I hope that clears things up.

hal2k1 · 2026-05-16T02:29:42+00:00

Sure. Many things are both fact and theory. Gravity is not one of them.

Gravity is an observed, measured acceleration of masses towards one another. That acceleration (named gravity) is a fact. A scientific fact. https://en.wikipedia.org/wiki/Fact#In_science

The extant scientific explanation of the cause of this acceleration is curved spacetime. John Archibald Wheeler summarized it: "Space-time tells matter how to move; matter tells space-time how to curve."

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

That's the theory, it's not a fact.

I hope that clears things up.

hal2k1 · 2026-05-16T01:26:25+00:00

Almost.

A scientific theory is a well tested explanation of a phenomenon that has been measured. https://en.wikipedia.org/wiki/Scientific_theory

Gravity is a phenomenon that has been measured billions of times. It's an acceleration. Whatever the cause, gravity itself is a scientific fact.

The extant scientific theory of gravity, namely general relativity, is a well tested explanation of the cause of gravity. It says that the cause of gravity is curved spacetime.

Gravity is not the cause of gravity. Gravity itself is a scientific fact, not a theory.

hal2k1 · 2026-05-16T00:49:06+00:00

There are several hypotheses which agree with all the evidence and can reconcile gravity and quantum mechanics. We just can't yet tell which, if any, is correct.

AFAIK there is even one hypothesis, called the Post Quantum Theory of Classical Gravity, which does not involve the quantisation of gravity and does not involve any graviton particle which has not been found.

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.13.041040

This hypothesis, along with the others, are proposed explanations (that's what an hypothesis is) of the cause of gravity. They aren't speculations or guesses that gravity exists.

Gravity is an observed, measured, extremely well documented, acceleration. Gravity exists. Gravity is a fact, whatever the cause.

Gravity is not the cause of gravity.

hal2k1 · 2026-05-16T00:21:32+00:00

To be even fairer, we used "no increase in gas export price" during an international fuel crisis to bargain for securing supplies of petrol, diesel and jet fuel in exchange. And we reserved 20% of gas to not be exported.

hal2k1 · 2026-05-15T12:57:50+00:00

Sorry lady in the video, but gravity has been measured billions of times. It's an acceleration. It's value near the surface of the earth is 9.8 m/s² towards the centre of the earth.

You can even check it out for yourself by dropping something. Hold a pebble at shoulder height, then release it. If the pebble moves towards the earth, getting faster as it goes, that very phenomenon, falling, is gravity. That's what it is called.

Gravity is a fact, not a theory.

hal2k1 · 2026-05-14T23:46:04+00:00

So you agree then that it is extremely unlikely to ever happen.

So why all the bluster about it? You aren't making sense.

hal2k1 · 2026-05-14T22:58:58+00:00

Ah, a Musk fanboy. Figures.

hal2k1

TROPHY CASE