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Age of The Universe!

  • #1
Hi all,
Hoping you can help with this problem!

Homework Statement


For a flat universe, show that [tex] t_{0}=2/3 (H_{0})^{-1} [/tex] ? Seems like a simple problem I just don't really know where to start.

Homework Equations


Hubble's law [tex] v= H_{0}r [/tex]
and then [tex] t= 1/H_{0} [/tex]

The Attempt at a Solution


I just need guidance where to start. Flat universe means that expansion is constant in any direction right? What do I do?
 

Answers and Replies

  • #2
mgb_phys
Science Advisor
Homework Helper
7,774
12
flat universe means the hubble constant is constant.

Then 1/hubble constant has units time.
Think of the equations for something that doubles/halves with a constant time interval
 
  • #3
How about the kinematic equation: x(t)= vt + 1/2at^2
Not sure if this is right and what to do with it? maybe take a derivatives of both sides???
 
  • #4
I still can't figure out the answer, can someone give me a hint please
 

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