The Hubble Constant is the rate at which the universe is expanding. It first came to light when Edwin Hubble came up with the idea of a constant rate of expansion for the universe.
In 1919, Harlow Shapley observed the expansion of the universe, backing the proposal made by Edwin Hubble, for whom the Hubble Constant is namesake.
- The difference in measurements of the Hubble Constant has led scientists astray.
What is Hubble Constant?
- Hubble Constant, in terms of science, is a phenomenon that occurs on a universal scale – expansion of the universe at the same rate.
- The technology in Hubble’s time doesn’t compare to what’s available today. Yet he was able to use it for looking at space as far out as 900,000 light–years.
- This number is known as the Hubble constant after the astronomer, Edwin Hubble, who first proposed the idea.
- Since then, much finer telescopes have come and gone. In 1919, Harlow Shapley observed the phenomena, backing the proposal made by Edwin Hubble.
- The launch of Hubble telescope and Planck telescopes are a great asset to the refining of this Constant.
- Hubble telescope works by measuring and observing the luminosity and rotation speed of a galaxy.
- The Planck telescope is a telescope that measures the microwave background and radiation-emitting in the universe.
- It measures the microwave length of light present in our universe.
Fun Fact: Microwaves are not called microwaves because they are in the micrometre range of wavelengths. Rather because they are shorter compared to the radio technology which was earlier in use.
It finally comes down to how much?
- Let’s define the unit of measurement which is prevalent in use – Kilometer/second per Megaparsec.
- This means Universe is expanding a certain number of kilometres per second for every Megaparsec.
- That’s out of the way. Here’s the mind-blowing part – Megaparsec is a measurement of the volume of the universe.
- 1 Megaparsec is equal to 300 Million Lightyears cubic volume of the Universe.
- ESA’s Planck telescope measures the speed as 67.4 km/s per Megaparsec.
- When using Cepheids method of measurement, the same comes out to be 73.4km/s per Megaparsec. Scientists are up all night trying to figure this one out.
Implications for the Hubble Constant
- These calculations are meant to ascertain the Hubble Constant’s exact value. The discrepancies can mean one of two things.
- The way astronomers measure distances at the universal scale is wrong or
- There needs to be in place a different exotic law of physics that we know nothing about.