In the Dark

I haven’t mucked out my spam folder for a while and when I did so just now I found that a long-term irritant of mine, a certain Mr David Hine, had attempted to post another comment:

I have to admit that I’m not well up on the biblical references so I looked them up. Isaiah Chapter 40 Verse 22

He sits enthroned above the circle of the earth, and its people are like grasshoppers. He stretches out the heavens like a canopy, and spreads them out like a tent to live in.

I don’t see any mention of the Hubble constant, nor indeed any statement that the stretching of the heavens follows a linear relation (Hubble’s Law).

As for Psalm 2, in the New International Version, Verse 1 reads:

Why do the nations conspire
    and the peoples plot in vain?

I have only just now realized that the second part of this verse refers to the construction of graphs. Personally, I never plot in vain. I normally use python.

UPDATE: I have now received further information of the derivation of the Hubble constant straight from the horse’s arse mouth:

Unfortunately I am so lacking in mental equipment I can’t really understand this equation. It’s not even an equation actually because it doesn’t equate anything with anything.

Anyway, let’s look at the expression given in the above comment. A Megaparsec has the units of length. The speed of light has units of length/time, so  whatever the formula calculates has units of length² time^-1, which is dimensionally incorrect for the Hubble constant, which has units of time^-1.

Moreover, if I put values for c, π, 21 and 2 into the equation I don’t even get anything like 70.98047:

π²¹ ≈ 2.75 × 10¹⁰ (dimensionless).

2 × `a Mpc’ × c ≈ 2 × 3.086 ×10²² m × 3 × 10⁸ m s^-1 ≈ 1.83 × 10³¹ m² s^-1.

Thus the full expression has a value approximately 6.66 × 10²⁰ m² s^-1.

The correct value for the Hubble constant is about 2.2 × 10⁻¹⁸ s⁻¹.

Completely wrong value and completely wrong dimensions. The first three figures of the answer may be significant however.

Here’s some reasoned criticism:

I’ve checked the above calculation and don’t see any mistakes. Perhaps I forgot to take away the number I first thought of…