Measuring the Hubble Constant Better

eldavojohn writes "The Hubble Constant is used for many things in astrophysics: from determining how fast things are moving away from us, to the total volume of the universe, to predicting how our universe will end. The current best value for the Hubble Constant is 74.2 ± 3.6 (km/s)/Mpc according to recent conventional methods and the recently restored Hubble Telescope. Most astronomers agree that that's within 10% of its actual value. Researchers now claim that they might be able to get to 3% using water molecules in galactic disks to act as masers that amplify radio waves, to analyze galaxies seven times as far away as the current measurements. The further away the 'standard candle' is, the more assured they can be that local effects are not skewing the measurements. From one of the researchers: 'We measured a direct, geometric distance to the galaxy, independent of the complications and assumptions inherent in other techniques. The measurement highlights a valuable method that can be used to determine the local expansion rate of the universe, which is essential in our quest to find the nature of dark energy.' Once the Square Kilometer Array is completed, they hope to get even closer to the actual value."

Comments

*Checks the Hubble Constant*

[Alzheimers]

Yep, he's still dead.

Re:*Checks the Hubble Constant*

[Red Flayer]

So is the value 0 or 1?

I'd assume the dead state is 0, and the live state is 1 -- except Hubble was living while he calculated the value, so he may have assigned 0 to the live state, and 1 to the dead state. Or he might have foreseen my current problem and switched the values just to trick me.

Speaking of which (my current problem), it appears my doomsday machine has entered into a positive feedback loop, and I'll only know how to fix it and save the planet if I have the correct value. I'd appreciate an accurate (and swift) answer if you can kindly help me.

Re:*Checks the Hubble Constant*

[Red Flayer]

The doomsday machine output should have a value with a lower limit of 0 and an upper limit of 1. Fractional parts should be rounded to the nearest integer.

Poppycock.

The outcome of my doomsday machine is DEATH. And SUFFERING. Also, some Mountain Dew. But mostly DEATH.

Re:*Checks the Hubble Constant*

[Chris Burke]

Yep, he's still dead.

But that measurement is only accurate to within 10%.

Re:Hubble constant now a misnomer

[American Expat]

It's just obeying the first rule of computer science: Constants aren't
(second rule: Variables won't)

Re:How big?

[JustOK]

about 298997.51157527 square fathoms. HTH.

Re:Volume of universe?

[JohnFluxx]

Good grief, I'm off by a factor of a billion and people complain. So picky :P

Re:no, that's not right

[BizzyM]

Universe expansion will create causal separation in the future, but not the past. It doesn't limit how far away you can see something, because you are looking at something in the past, but it does prevent you from going there. Because looking backward in time, the universe is shrinking, and you can see more and more of the universe going back. Looking forward in time, everything is getting more separated, and, for far regions of space, the rate of separation is higher than light can catch up to.

You just blew my mind