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Galaxy Clusters' Stunted Growth Confirms Dark Energy
A new study of 86 galaxy clusters in the early universe has provided independent confirmation of the existence of dark energy. In its absence, gravity's pull should have caused the number of clusters to increase by a factor of 50 over the last 5.5 billion years. What is observed is a factor of 10 increase. "Together with earlier observations... the new data strengthen the suspicion — but do not prove — that dark energy is a weird antigravity called the cosmological constant that was hypothesized and then abandoned by Albert Einstein as a 'blunder' almost a century ago. If that is true, the universe is fated to empty itself out eventually, and all but the Milky Way's closest neighbors will eventually be out of sight. ... Adam Riess of Johns Hopkins and the Space Telescope Science Institute, said: 'If this was a fox hunt and dark energy was the fox, I think they have closed off another escape route. But there is still a lot of terrain left for the fox, and we've seen little more than a glimmer of fur.'"
(Sigh). Everytime I see a story about the cosmological constant I have to see the obligatory "that dark energy is a weird antigravity called the cosmological constant that was hypothesized and then abandoned by Albert Einstein as a 'blunder' almost a century ago." as if Einstein was so smart he predicted dark energy 100 years ago. No. He put a term in the equation to stabilize the universe, which was then thought to be static, against gravity. Then it turned out the universe wasn't static, it was expanding. That was the blunder. If there's an outward force, as there now seems to be, you'd put a term in the same place. But it's based on new data. I'm sick and tired of the "Aha! Einstein was right all along and he didn't even know it!" comment that has to be stuffed in every cosmological constant story these days.
Surely Occam's Razor comes into play here? Surely it's obviously simpler to say 'we've got the maths wrong for gravity beyond solar system scale' and start again at the chalkboard?
Which is, in effect what we are saying. However, it makes little sense to simply scratch the whole, current understanding of the world and start over; introducing an assumption that gravity behaves differently outside a certain distance begs the question why it should be so, and we don't have any compelling answer to that.
My own favourite, which admittedly comes out of thin air, is that negative gravity corresponds to negative mass. If you look at the classical equation as a rough approximation, you'll see that a negative mass should repel a positive mass, but attract another negative mass. Intuitively this seems to potientially explain the "dark energy" phenomenon, and it might explain how, at the beginning, mass seems to have been created from nothing - perhaps an equal amount of positive and negative mass was created, so that mass was preserved, in total, and then it exploded apart. How about that for an explanation?
It also interacts with the photons we can see. Otherwise, the refractive index of air would be exactly 1, instead of 1.00029
The Tao of math: The numbers you can count are not the real numbers.