Spitzer confirms cosmological inflation

[Jackalope]

A team of astronomers, using NASA's Spitzer space telescope has confirmed cosmological inflation and has refined the error range of acceleration to 74.3 +/- 2.1 km/megaparsec (the Hubble constant).

Unlike NASA's Hubble Space Telescope, which views the cosmos in visible light, Spitzer took advantage of long-wavelength infrared light to make its new measurement. It improves by a factor of 3 on a similar, seminal study from the Hubble telescope and brings the uncertainty down to 3 percent, a giant leap in accuracy for cosmological measurements. The newly refined value for the Hubble constant is 74.3 plus or minus 2.1 kilometers per second per megaparsec. A megaparsec is roughly 3 million light-years. (*)

(*) A megaparsec is 3.26 light-years.

[Polaris]

I find it funny it is called a constant.

[Jackalope]

I find it funny it is called a constant.

Why is that? It's no less a constant than the rate of acceleration due to Earth's gravity (9.8 m/s^2). It isn't the speed from the POV an observer that's constant, but rather the rate of acceleration per unit of distance (or time, in the case of my example).

[Cyberman]

Rather like the term Big Bang, 'Hubble Constant' is something of a misnomer. More accurately it's called the Hubble Parameter, as it depends on time. It's the proportion between the recession velocity of galaxies and their distance.

[Jackalope]

Rather like the term Big Bang, 'Hubble Constant' is something of a misnomer. More accurately it's called the Hubble Parameter, as it depends on time. It's the proportion between the recession velocity of galaxies and their distance.

Yeah, "Big Bang" is an unfortunate name which, as the story goes, was coined by Fred Hoyle, a proponent of the steady-state model. It's not an accurate term in any sense, but alas, it stuck.

[Polaris]

I find it funny it is called a constant.

Why is that? It's no less a constant than the rate of acceleration due to Earth's gravity (9.8 m/s^2). It isn't the speed from the POV an observer that's constant, but rather the rate of acceleration per unit of distance (or time, in the case of my example).

It is only a constant at this relative point in time. The acceleration is not constant over the geologic timescale.

[Cyberman]

Perhaps you misspoke there; the geologic timescale is a heartbeat in comparison with cosmic time.

[Jackalope]

Why is that? It's no less a constant than the rate of acceleration due to Earth's gravity (9.8 m/s^2). It isn't the speed from the POV an observer that's constant, but rather the rate of acceleration per unit of distance (or time, in the case of my example).

It is only a constant at this relative point in time. The acceleration is not constant over the geologic timescale.

I'm sure you meant "cosmologic timescale". Point taken, though. It's observed to be constant at this point in time, and thought to have been so for quite some time (perhaps half the age of the universe). Of course, we don't know the latter with any certainty.

[popeyespappy]

Perhaps you misspoke there; the geologic timescale is a heartbeat in comparison with cosmic time.

Not necessarily. The Earth is currently about 1/3 the age of the universe. When the Earth is twice as old as it is now it will be about 1/2 the age of the universe. If it makes it to 3 times its current age it will be about 60% of the age of the universe. If Earth survives the expansion of the sun it is not beyond the realm of possibility that it could last for trillions of years. At which point for all practical intents and purposes geological time will be the same as cosmic time.

[Polaris]

Perhaps you misspoke there; the geologic timescale is a heartbeat in comparison with cosmic time.

Not really much difference as both deal in billions of years. Only way I would see a real significant difference would be if I still believed in the collapsing universes theory.

It is not believed to be constant because of the believed exponential effects of dark energy.