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I am confused about the age of the Universe.

If you calculate it by $1 / H_0$, won't the answer be roughly the same today as it will be 30 billion years from now?

I know $H_0$ is a parameter, not a constant, but it doesn't change that much, does it?

And if the expansion is accelerating then $H_0$ is going up, implying the age of the universe $1 / H_0 $ was higher in the past than it is today.


marked as duplicate by Qmechanic Sep 25 '13 at 20:42

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    $\begingroup$ Possible duplicates: physics.stackexchange.com/q/69050 and physics.stackexchange.com/q/10400 $\endgroup$ – Kyle Kanos Sep 25 '13 at 19:29
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    $\begingroup$ As I said in the message I know Hubble's parameter is not constant. At the moment it is getting larger, right? Because expansion is accelerating. That would imply that in the future the age of the universe (1 / H_0) is smaller? $\endgroup$ – MikeHelland Sep 25 '13 at 19:36
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    $\begingroup$ Have you read my answer here, and other answers to related questions? It seems like that explains what you want to know... $\endgroup$ – David Z Sep 25 '13 at 19:40
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    $\begingroup$ It seems to say as the universe gets older, H_0 gets smaller. But H_0 is getting bigger according to the acceleration of the expansion. It seems to me like you are defining H_0 in terms of the age of the universe and then using it to compute the age of the universe. $\endgroup$ – MikeHelland Sep 25 '13 at 19:47
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    $\begingroup$ The accelerated expansion implies that $\dot{a}$ increases (the derivative of the scale factor). But the Hubble parameter is defined as $H = \dot{a}/a$, which decreases. The age of the universe is calculated here: physics.stackexchange.com/a/63673/24142 and here: physics.stackexchange.com/a/69052/24142 $\endgroup$ – Pulsar Sep 27 '13 at 21:44

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