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Author Topic: Dark energy? Are we just making things harder than they need to be Lorentz?  (Read 10338 times)

Offline Ęthelwulf

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( I think, if my memory serves)
 

Offline Messenger

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Right, I checked the link. It appears to be the sixth equation in your reference. I am still a bit confused, never -- not once have I seen a density be described as

d477be925a14d84f5d40f62909d1be2f.gif [1]

rather you always see it as

8f654be4d8114a344f46a7e0906e0a11.gif [2]

Which would mean this is not a usual density? Which still doesn't add up... for me at least.  If equation 2 has dimensions of density, then equation 1 cannot? No, is there something I am missing? Am I being stupid here?

References state that this equation came from  Elizalde, E. (1995) Ten Physical Applications of Spectral Zeta Functions (Berlin:Springer-Verla

I see your point too.  I will get a copy as this is an interesting question. May take me a week or so.
 

Offline Messenger

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Going back through some of your posts Yoron.  Interesting paper on dynamical equations. I agree with the title heh.
What you were writing about the black holes also got me to thinking about the Schwarzschild radius.  Haven't looked at in depth, but what mass-energy level is required of the cosmological constant to be able to make the radius possible?


As for Cern?

Depends on if you're right, right :)
And even if you are, you can't 'know' for sure.
What about the hard radiation they use as a proof for black holes being unable to form?

I'm still trying to see this one :)
You've had some time working it through, I need it too ::))


And thinking of it, if you are right we should find black holes rather alone?
Or put it as this, if they gets created in a system of a lot of stars the 'force' is attractive.
But if we find one alone, then maybe?

They should be very 'small' if so as they will repulse before attract?
But I'm still trying to wrap my mind around the idea, and it would most probably not constitute a 'proof'
 

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Sometimes good to read things like this as a sanity check.. http://www.npr.org/2012/03/16/148753430/adam-riess-one-cosmic-puzzle-solved-many-to-go [nofollow]

FLATOW: This expansive pushing-out force. But what is fascinating, most fascinating about this, and the more you talk about it, the more fascinating it gets, is that we didn't always - you just discovered it a few years ago, relatively speaking, and the dark energy didn't kick in as a force until relatively recently.

RIESS: That's right. Yeah, in fact it's quite interesting. If we had lived many billions of years ago, we could not have inferred the presence of dark energy, as it only started accelerating the universe a few billion years ago. And as Lawrence Krauss(ph) points out in his new book, there will come a point in the future when, if the universe keeps accelerating, galaxies will be so far away from us, most of them, we will not be able to see them anymore, and so we will lose the means to actually infer the universe is accelerating.

FLATOW: So before dark energy sort of kicked in, then we had gravity as a greater force pulling the universe back?

RIESS: That's right, attractive gravity, right.

FLATOW: And then what happened?

RIESS: And then as the universe got larger, the space between galaxies increased, and ordinary attractive gravity of the dark matter declined, just like you learn in physics class, as one over the distance squared. So the matter density is always dropping, but the density in this dark energy is about constant. So if something's falling, and something's staying the same, at some point the thing that's staying the same will win, and we are in that winning period.

FLATOW: And as you say, because the universe is expanding, that space has the dark energy in it, sooner or later it got greater than the attractive force of the gravity because space is getting bigger.

RIESS: That's right.

FLATOW: And why didn't we know about this until a few years ago?

RIESS: Well, you might say Einstein gave us a clue. Einstein wrestled with a problem back before we even knew the universe was expanding, and he was looking for a way to keep the universe from collapsing. And so he discovered, in his theory of gravity, something like this dark energy - he called it a cosmological constant - could play this role, pushing things away.
 

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