Galaxy Clusters Stunted by Gravity's Bizarro Twin: Dark Energy

By Eliza Strickland | December 16, 2008 5:23 pm

dark energyThe mysterious force known as dark energy that is causing the universe’s expansion to accelerate is also preventing galaxy clusters from getting too big for their britches, a new study suggests. The existence of dark energy was first proposed a decade ago but the stuff has never been directly detected, and there’s much we don’t know about it. However, all the indirect studies have agreed that it acts like a kind of anti-gravity: A repulsive force that permeates empty space and, bizarrely, grows stronger with distance, precisely the opposite of what happens with gravity [Washington Post].

In the new study, researchers used NASA’s orbiting Chandra X-ray observatory to examine the growth patterns of galaxy clusters. After bulking up rapidly in the first 10 billion years of cosmic time, clusters of galaxies, the cloudlike swarms that are the largest conglomerations of matter in the universe, have grown anemically or not at all during the last five billion years, like sullen teenagers who suddenly refuse to eat. “This result could be explained as arrested development of the universe” [The New York Times], said lead researcher Alexey Vikhlinin. He says the findings support the idea that the gravity of the clusters drew in more and more matter for billions of years during their growth spurts. But gravity’s alter ego, dark energy, was tugging at the edges of the clusters, pulling matter away from the galaxies and stalling growth.

The results, which will be published in The Astrophysical Journal, are seen as another confirmation that dark matter exists. They also strengthen the suspicion — but do not prove — that dark energy is the result of a weird antigravity called the cosmological constant that was hypothesized and then abandoned by Albert Einstein as a “blunder” almost a century ago [The New York Times]. Einstein’s idea of the cosmological constant didn’t work mathematically, but evidence is gathering for his basic idea that some anti-gravity force must pervade empty space to keep the universe from collapsing through the force of its own gravity.

DISCOVER’s crack astronomy and physics bloggers have much more on this finding, including what it means for the ultimate fate of the universe and some nifty graphs.

Related Content:
Bad Astronomy: NEWS: Dark energy stunts your growth
Cosmic Variance: Dark Energy: No Longer a Surprise
80beats: Caught in the Act: Dark Energy Expanding the Universe

Image: MPE/V. Springel

CATEGORIZED UNDER: Physics & Math, Space
  • nick

    “A repulsive force that permeates empty space and, bizarrely, grows stronger with distance, precisely the opposite of what happens with gravity”

    So, when we harness this technology, we should be able to shoot things into space that will get faster the further away they are from the power source here on earth shooting them up. We’d probably just need a device based on the railgun concept, with dark energy instead of electromagnetism as the accelerating source.

    What, you scoff at the idea? Who scoffed at the idea of harnessing the power of the sun for destructive or constructive purposes. Who scoffed at the idea of going to the moon, let alone space?

    If we can imagine it, we can do it, or at least fake it ’till it’s good enough for government.

    And it’s possible that both the gravity and antigravity forces we see at work are topological features of spacetime, just in the hidden dimensions posited by superstring theory. Who knows?

  • Robert K. Vanderhoek

    To be able to understand what dark energy is, it is necessary to understand the fundamental mechanics of the proton. The way it works electrodynamically. It’s all answered, dark energy, the cause of initial universal inflation, what caused the big bang. See:

  • Brian Uptain

    It’s funny really. I am not the brightest person rolling, but the description of what I see is more like an air bubble in water. imagine a glass of water. Now take a straw and blow a bubble into it. Since the bubble rises to the top it’s pretty easy to do for the most part. Now this next part will take a little imagination. We have all seen the the little toys from the 80’s that if you add water it will grow to a pretty large foot or fish or what ever, imagine that the air bubble acts in the same way. Now if the air bubble ( that reacts like that toy when water is added) is a Galaxy Cluster and the water is this dark energy, then it you could see how the Galaxy cluster or what ever would grow until it reaches the point that it can no longer absorb water. Or in this case transfer dark energy into something else. The air bubble reference was made regarding the surface tension of water within the air bubble. The larger the bubble the harder it is to put air into that same bubble. At some point though you will no longer be able to put air into the bubble because of the surface tension from around the air bubble. Which also does not hold a perfectly conforming shape. Almost like a cluster. Just a thought from a non scientific view.

  • Dan Thompson

    ” A repulsive force that permeates empty space…”. Sounds like an oxymoron to me. The area of the universe that doesn’t contain what we perceive as matter either is empty or it contains an energy throughout. It can’t be both.

  • Brian Uptain

    It’s all perspective. As a whimsical comparison, air is empty, but has enough energy to wipe man from the face of the earth. Space on a much more complex scale is the same way.

  • Dan Thompson

    Air is not empty. It is matter.

  • Bruce Wallman

    There are some forms of energy(?) that appear to be bi-directional and others that appear to be unidirectional. Time is also unidirectional. I am not ready for dark energy and dark matter until someone can show me what gravity and time are, why gravity (not light) and time appear to be strictly related by relativity, and why both flow in one direction – as does entropy.

  • m

    I thought the curvature of space-time “stretched” or “flattened” the further away it got from incredibly massive bodies. We…as occupants of a massive body…would it not appear to us that other masses would be moving faster and faster from us as space-time flattened out? (You should have seen my Physics prof’s face when I asked him that during out discussion on relativity). I may only be a student…but I’m am having a very hard time buying into Dark Energy. We know space-time curves as it approaches a massive body. So to does it “flatten out” as it moves away from a massive body. As we observer the process of the “flatten out”, it would look to us to be accelerating. But it couldnt be because the speed of light doesn’t change. To me, dark energy is “lazy imagination” (intended as humorous… i am by no means an expert!! )

  • Brian Uptain

    I know air is not empty in the literal sense, but neither is space. Which is the comparison I was trying to make. M’s look of what we currently know and how we perceive this information points to the most interesting of points. “What if?”. With infinite possibilities, everyone know matter how outlandish could be right. Until proven otherwise the world was flat, until proven otherwise, Ra, made the sun rise. All of these previously absolutes of that era’s science were found not to be accurate. But in that same token, the absolute science of today, could be looked at as some child’s joke about what is, in the future.

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