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johne1618
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Does the measured value of the Hubble constant, H_0, depend on the details of the expansion model one uses?
That depends somewhat upon how it is measured. If it is inferred from far-away observations, such as the Cosmic Microwave Background, then the answer is yes. But our most accurate measurements of [itex]H_0[/itex] are from nearby observations where the expansion rate hasn't changed enough for it to really matter what our model of the expansion is.johne1618 said:Does the measured value of the Hubble constant, H_0, depend on the details of the expansion model one uses?
What? Why are you bringing this up? Because it sounds completely off-topic to me.Vorde said:The Hubble Constant is not dimensionless (i.e., it will change depending on the units you are using), I know that slightly different values have been collected depending on the method used (all within error bars), I believe that the Cosmological Constant can be given a arbitrary value in Einsteins GR equations, although there is only a small range where the value would be reasonable.
The reason I bring both up is that while the Hubble Constant is based on observation, the Cosmological Constant is based in the equations.
The Hubble constant is a measure of the rate at which the universe is expanding. It is typically denoted by the symbol 'H' and has units of kilometers per second per megaparsec (km/s/Mpc).
The expansion model, also known as the cosmological model, dictates the behavior and evolution of the universe. Different models can predict different values for the Hubble constant based on factors such as the amount of matter and energy in the universe, and the rate of expansion.
No, despite its name, the Hubble constant is not a fixed value. It is actually a time-dependent quantity that can change as the universe evolves. Scientists continue to refine their measurements of the Hubble constant in order to better understand the nature of the universe.
There are several methods used to calculate the Hubble constant, including the distance ladder method, which relies on measuring the distances to nearby galaxies and using their known properties to estimate the expansion rate of the universe. Other methods include observations of the cosmic microwave background radiation and the use of standard candles, such as Type Ia supernovae, to measure the expansion of the universe.
The value of the Hubble constant has been a subject of debate among scientists for decades, as different measurement techniques and data sets have yielded slightly different values. This has led to ongoing research and discussions about the accuracy and precision of the Hubble constant and its implications for our understanding of the universe.