Found some new info on Dark Energy and its possible existence Have a listen and Let me Know what you think.

 

http://earideas.com/earideas/explore/show/60159/Study+Shines+Light+On+Existence+of+Dark+Energy

 

*Scroll down mid page hit play button /adjust volume

When he was talking about empty space energy, I thought of an interesting opinion I heard (IIRC it was Richard Muller). He said that maybe vacuum repells itself somehow, and as this repulsion takes place, mroe vacuum is 'created' hence the repulsion increases and it goes on.

 

btw: accepting for a moment that cosmological constant changes, why is it then called a constant?

 

thanks for sharing

*Quick question what is this IIRC

 

Wow never thought of the notion of a vacuum that repels it self it is a new way to think about it,that is if it holds and water.

 

I am sure there is some technical reason that it is still call it a constant or it just stuck.

If I Remember Correctly

When he was talking about empty space energy, I thought of an interesting opinion I heard (IIRC it was Richard Muller). He said that maybe vacuum repells itself somehow, and as this repulsion takes place, mroe vacuum is 'created' hence the repulsion increases and it goes on.

 

btw: accepting for a moment that cosmological constant changes, why is it then called a constant?

 

thanks for sharing

 

The cosmological constant only changes relative to our present time. Relative to the cosmos it is constant, it is the cosmos that changes.

The cosmological constant only changes relative to our present time. Relative to the cosmos it is constant, it is the cosmos that changes.

Thank you for that:-)

The cosmological constant only changes relative to our present time. Relative to the cosmos it is constant, it is the cosmos that changes.

 

Can you please provide a reference for this, since when does the cosmological constant change with time ?

 

You can plug in different values to describe a vacuum e.g negative or positive pressure, but that's different from what you've stated.

Can you please provide a reference for this, since when does the cosmological constant change with time ?

 

You can plug in different values to describe a vacuum e.g negative or positive pressure, but that's different from what you've stated.

 

You are absolutely correct, I should have said if the cosmological constant changes. I will try to find where I was reading about it possibly changing over time but it was not recently.

I love listening to the podcast of NPR "Science Friday".

 

I caught one on "dark energy", which discussed such things as determining the speed (acceleration?) of very distant (and thus old) galaxies, etc.

 

The perhaps single most interesting thing is that they computed that dark energy - the stuff that pushes the universe apart - appeared about 7 billion years ago!

 

This means, that up until 7B years ago, the universe expanded at a rate consistent with big bang theory, and ... ummm... relatively traditional physics, BUT, starting then at 7B, the remote galaxies start accelerating -- the expansion of the universe accelerates.

 

The idea that there is "vacuum energy", and that that may be "dark energy" is fascinating - but perhaps the vacuum needs to be "more complete" or "have stuff further away to start this phenomenon", which would explain why there is a time frame where the vacuum isn't empty enough?

 

Anyway, fascinating discussion.

 

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Since this is my first post, I will add that I'm Ward Christensen, then inventor of the world's first BBS, that Randy Suess (HW) and I put together in the late 70's. I patterned it after a "cork board and push-pins" kind of physical bulletin board, and the term (BBS) stuck. This was a bit after I did the modem.exe file xfer program, later renamed Xmodem, the first popular protocol between "microcomputer".

You are absolutely correct, I should have said if the cosmological constant changes. I will try to find where I was reading about it possibly changing over time but it was not recently.

 

Sorry for the blunt reply npts2020, I was at work on Christmas Eve, everyone else was down the pub So I was staring at the equations scratching my head after reading your post....of course after massive time periods there's no reason to believe the value wouldn't change.

 

I remember reading, even the fine structure constant would be subject to change if you turn the clock back enough, IIRC around 7 billion years, so I'll look for a link.

 

In the meantime, here's a link to npr, which I believe covers WardXmodem's post. Don't have time to listen to it right now...I really should be studying.

 

http://www.npr.org/templates/story/story.php?storyId=98499894