The other explanation for the observed expansion of the universe is that c changed, but that AFAIK has been debunked (is that the ‘tired light’ hypothesis’?)
;-)
"Observed expansion"
Wrong!
Redshift is observed, not expansion. Expansion is interpreted!
"Observed expansion"
Wrong!
Redshift is observed, not expansion. Expansion is interpreted!
You need to learn to "categorize".
For example, observation (red shift) and interpretation (expansion) are different categories.
And also object (matter) and concept (space, time).
Without this to be able "science" does not go.
For example, observation (red shift) and interpretation (expansion) are different categories.
And also object (matter) and concept (space, time).
Without this to be able "science" does not go.
I am getting a severe headache reading @cumbb.
I watched his Ed Dowdye video and thought it was Crank stuff from someone who really doesn't understand the subject. Ron Hatch was a similar woo monger.
Earlier cumbb pooh-poohed bending of starlight by the mass of the Sun in Eddington's famous (1919?) experiment during an eclipse.
So what is going on here, cumbb? I am seeing gravitational lensing.
https://www.sciencenews.org/article/james-webb-space-telescope-first-image-galaxy-stars-data
Maybe you should study it further before criticising it.
I think Galu mentioned that the singularity at the Black Hole Event Horizon goes away with a change of coordinates.
This is right:
https://en.wikipedia.org/wiki/Eddington–Finkelstein_coordinates
The central singularity then becomes a moment in future time rather than a point in space. All quite hard to grasp, I really need to learn more maths.
I shall be revisiting Electromagnetism, things like the Vector Potential in 4D. Maxwell's famous 4 equations become a mere 2 in 4D Spacetime.
I watched his Ed Dowdye video and thought it was Crank stuff from someone who really doesn't understand the subject. Ron Hatch was a similar woo monger.
Earlier cumbb pooh-poohed bending of starlight by the mass of the Sun in Eddington's famous (1919?) experiment during an eclipse.
So what is going on here, cumbb? I am seeing gravitational lensing.
https://www.sciencenews.org/article/james-webb-space-telescope-first-image-galaxy-stars-data
Maybe you should study it further before criticising it.
I think Galu mentioned that the singularity at the Black Hole Event Horizon goes away with a change of coordinates.
This is right:
https://en.wikipedia.org/wiki/Eddington–Finkelstein_coordinates
The central singularity then becomes a moment in future time rather than a point in space. All quite hard to grasp, I really need to learn more maths.
I shall be revisiting Electromagnetism, things like the Vector Potential in 4D. Maxwell's famous 4 equations become a mere 2 in 4D Spacetime.
Last edited:
@Bonsai The tired light hypothesis suggests that photons lose energy as they travel large distances through space, which results in the wavelength increasing, i.e., shifting towards the red end of the spectrum.
The tired light hypothesis therefore attempts to explain the redshift of far away galaxies and offers an alternative to the expanding Universe theory.
New observations by the JWST apparently suggest that the Universe is much older than previously thought, prompting some cosmologists to look again at the tired light hypothesis.
The tired light hypothesis therefore attempts to explain the redshift of far away galaxies and offers an alternative to the expanding Universe theory.
New observations by the JWST apparently suggest that the Universe is much older than previously thought, prompting some cosmologists to look again at the tired light hypothesis.
Should be interesting the next few years. If the velocity of c does change, it would call into question many aspects of physics as we know it.
Yes this I also found. But I was more interested how small the circle is 1km from the sun that projects the earth....
//
That's what happens when you let someone inside your head.
Don't give them the satisfaction of seeing your discombobulation!
Let's see, diameter of the sun ... "The Sun is the largest object in our solar system. Its diameter is about 865,000 miles (1.4 million kilometers)." Using 8,000 miles as a gross approximation of the diameter of the Earth, the ratio is (grossly approximately) 1,000 to 1. The equivalent circle on Earth would be about 1 meter from its surface, and so would be exposed to a VERY small area of the Earth's surface. Hmm, distance you can see to the horizon ... "On a clear day, you [I presume with your eyes about 1 meter above the Earth's surface] can see for up to 3 miles before the horizon due to the curvature of the earth." At that close distance to the Sun, the circle will need a rather large diameter (compared to if it were the same distance from the Sun's center but the Sun were much smaller, approximating a point source) to capture the amount of energy that hits the Earth. There's ways to calculate this but it may involve calculus, but I rarely used calculus in my career, and don't remember enough of the two quarters I took in college, so the solution is left as an exercise for the reader.
I suspect ChatGPT can answer this question. I’m finding it’s like having a 20 year with an IQ of 150 sitting next to one. Vast store of knowledge and huge breadth, but not much depth. However, it’s quite good at solving math problems like this.
Just don’t ask it what a CFA is or how it works. You will get garbage back.
Just don’t ask it what a CFA is or how it works. You will get garbage back.
TNT's diagram shows a cone with its apex at the centre of the Sun and having a circular base with a radius, R, equal to that of the Earth's.
I order to find the radius, r, of the circle located at the ? mark, one could perhaps use the fact that the ratio of radius to height of a cone is the square root of two.
Alternatively, plug the relevant distance and radius numbers into the following Cone Calculator, TNT, and Bob may be your uncle! 😗
https://www.calculatorsoup.com/calculators/geometry-solids/cone.php
I order to find the radius, r, of the circle located at the ? mark, one could perhaps use the fact that the ratio of radius to height of a cone is the square root of two.
Alternatively, plug the relevant distance and radius numbers into the following Cone Calculator, TNT, and Bob may be your uncle! 😗
https://www.calculatorsoup.com/calculators/geometry-solids/cone.php
You've got a right angled triangle in the cone, so opposite/adjacent (r/h in the diagram below) gives the tan of angle at top of triangle.
In your diagram that's the radius (R) of the Earth divided by the distance to the centre of the Sun.
In your diagram that's the radius (R) of the Earth divided by the distance to the centre of the Sun.
No angles needed. It's a similar triangles problem. You need to know the radius of the Earth (4000 miles ), the radius of the Sun (425,000 miles IIRC) and the radius of the Earth's orbit (93 million miles).
I already have done the calculation. The radius of the circle at or near the Sun's surface comes out to be approx 4000 miles / 220. Not very big. 18 miles?
I make it the Earth gets about half a billionth of the Sun's light output. You don't need to know the size of the Sun for that one. My calculator is hiding, so I had to do it with pencil and paper.
I already have done the calculation. The radius of the circle at or near the Sun's surface comes out to be approx 4000 miles / 220. Not very big. 18 miles?
I make it the Earth gets about half a billionth of the Sun's light output. You don't need to know the size of the Sun for that one. My calculator is hiding, so I had to do it with pencil and paper.
Last edited: