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avery
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hi,
what is the total entropy of the universe today?
thank you
what is the total entropy of the universe today?
thank you
avery said:hi,
what is the total entropy of the universe today?
thank you
clamtrox said:If the universe has a cosmological constant, then it also has a de Sitter-horizon, whose entropy is much larger than anything inside. So to answer your question you'd need to know what dark energy is.
marcus said:I don't think we have any convincing evidence that there is a "dark energy". The observed accel. of expan. is simply and neatly explained by a positive cosmological constant Lambda.
avery said:hi,
what is the total entropy of the universe today?
thank you
clamtrox said:If the universe has a cosmological constant, then it also has a de Sitter-horizon, whose entropy is much larger than anything inside. So to answer your question you'd need to know what dark energy is.
marcus said:Clamtrox, I highlighted what I was responding to. I don't think you need to know what "dark energy" is in order to estimate the total entropy today.
marcus said:Some of your comments are explicitly addressed by the Bianchi et al article I linked earlier. Have you by any chance read it? Might find it interesting.
Google "bianchi prejudices constant" and get http://arxiv.org/abs/1002.3966
We seem to be coming from widely different places. The matter content has been measured. The standard LambdaCDM model gives the simplest good fit to the data and Lambda has been measured. From my perspective the distance to the cosmic event horizon is known---as I recall some 15 billion ly.clamtrox said:Of course it does - just plug a different matter content into Friedmann equation and you get a different horizon size.
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marcus said:We seem to be coming from widely different places. The matter content has been measured. The standard LambdaCDM model gives the simplest good fit to the data and Lambda has been measured. From my perspective the distance to the cosmic event horizon is known---as I recall some 15 billion ly.
clamtrox said:...
I think the Lineweaver article is very reasonable, but I also felt like there should be a proviso that this relies heavily on the assumptions put into the standard cosmological model.
marcus said:I don't think we have any convincing evidence that there is a "dark energy". The observed accel. of expan. is simply and neatly explained by a positive cosmological constant Lambda.
This is a constant naturally occurring in the Einst. law of gravity just as the Newton constant G occurs. To estimate total entropy we need to measure the constant Lambda, which has been done. We do not need to speculate about what the constant "is".
Google "bianchi prejudices constant" and get http://arxiv.org/abs/1002.3966
a critique of the hype surrounding "dark energy" talk.
The total entropy of the universe today is a measure of the disorder or randomness of the entire universe. It takes into account all forms of energy and matter, including the expansion of the universe.
The total entropy of the universe is calculated by adding up the entropy of all systems within the universe. This includes the entropy of stars, galaxies, and other objects, as well as the entropy of cosmic radiation and other forms of energy.
The second law of thermodynamics states that the total entropy of a closed system will always increase over time. Since the universe is considered a closed system, its total entropy will continue to increase as the universe expands and becomes more disordered.
It is highly unlikely that the total entropy of the universe will ever decrease. The second law of thermodynamics states that entropy can only increase or remain constant, but it cannot decrease. Therefore, the total entropy of the universe is expected to continue increasing indefinitely.
The total entropy of the universe plays a crucial role in determining the fate of the universe. As the entropy of the universe increases, the energy available for work decreases, leading to the eventual heat death of the universe. This is a possible scenario for the end of the universe, as predicted by the second law of thermodynamics.