A couple of weeks ago we looked at a concept called "Flow": being in the moment, in the groove, completely centered, a very internal idea connected to the nature of consciousness and our interface with reality. This time we're going to look at a very different and much more external concept from cosmology called "Dark Flow". The illustration below is credited to NASA and comes from an article published a few months ago in New Scientist magazine, entitled "Mystery 'dark flow' extends towards edge of universe". The article, written by Marcus Chown, begins with these paragraphs:
SOMETHING big is out there beyond the visible edge of our universe. That's the conclusion of the largest analysis to date of over 1000 galaxy clusters streaming in one direction at blistering speeds. Some researchers say this so-called "dark flow" is a sign that other universes nestle next door.
Last year, Sasha Kashlinsky of the Goddard Space Flight Center in Greenbelt, Maryland, and colleagues identified an unusual pattern in the motion of around 800 galaxy clusters. They studied the clusters' motion in the "afterglow" of the big bang, as measured by the Wilkinson Microwave Anisotropy Probe (WMAP). The photons of this afterglow collide with electrons in galaxy clusters as they travel across space to the Earth, and this subtly changes the afterglow's temperature.
The team combined the WMAP data with X-ray observations and found the clusters were streaming at up to 1000 kilometres per second towards one particular part of the cosmos (The Astrophysical Journal Letters, vol 686, p L49).
Many researchers argued the dark flow would not turn up in later observations, but now the team claim to have confirmed its existence. Their latest analysis reveals 1400 clusters are part of the flow, and that it continues to around 3 billion light years from Earth, a sizeable fraction of the distance to the edge of the observable universe (arxiv.org/abs/0910.4958). This is twice as far as seen in the previous study.
A direct link to the above video is at http://www.youtube.com/watch?v=UzDfIRMeOkY
In that entry we looked at a Seed magazine article by Raphael Bousso, a theoretical physicist at The University of California, Berkeley. The image he painted for us of the multiverse is that if we were to head off in a particular direction in our universe, we would eventually (after traveling for a very very very long time!) get to some other universe with different basic physical laws. This might seem to imply that we need no more than 4D spacetime, but also then presents us with a difficult to imagine process where once we got to the "edge" of our universe with its unique physical laws, we would encounter some kind of a difficult transition to another universe that has its own unique physical laws.
In You are the Point we talked about the cosmological horizon, and the idea that no more matter where you go in our universe you will ultimately observe yourself to be at the center. Doesn't Dr. Bousso seem to be opposing this viewpoint? Isn't this like claiming the world is flat and that if we travel far enough we will fall off the edge? One might get that impression. But since Dr. Bousso is a string theorist, I would say that what he's really telling us is that we would need to be moving through the extra dimensions to make such a journey to another different-initial-conditions universe, an idea that would then connect much better with my approach to visualizing the dimensions. We looked at similar concepts in The Holographic Universe, here's the video for that one again:
A direct link to the above video is at http://www.youtube.com/watch?v=hMLVjFrtq6Q
Coincidentally, in this video we looked at another New Scientist article written by Marcus Chown, and at about the 1:14 mark we show the cover of the issue that article came from, which has the headline "You are a Hologram Projected from the Edge of the Universe". At the 5:55 mark, I show some animations demonstrating some of the ways I'm proposing it's more useful to think about what the "edge of the universe" really is. This takes us back to the spatial dimensions that our reality comes from, and the important concept that each additional dimension is at "right angles" to the previous one. "What's Around the Corner" has turned out to be one of my more popular recent blogs showing how we can work through this logic one dimension at a time, please check it out if you still have questions about the validity of my approach and see if it helps to convince you.
Magnets and Flatlanders
Here's a visualization: imagine that our 4D spacetime is like the 2D plane that is home to our old friend, the flatlander. What would happen if we moved a magnet near that plane? In the flatlander's world, he would see objects moving towards the magnet's location, but have no way to see the magnet itself. That magnet is, in a sense "beyond the edge of the flatlander's world", in that it is in the third dimension rather than the second, at and additional right angle that is beyond his perception and perhaps even his ability to conceive.
Likewise, when cosmologists are suggesting that the observed evidence of "dark flow" is evidence for "universes next door" I would say the same analogy holds: this dark flow would be evidence of gravitational attraction coming from an additional dimension, one that is "outside" of our 4D spacetime in the same way that magnet was "outside" of the flatlander's 2D world.
"Dark flow" is still somewhat controversial, and even those scientists who accept its existence as a phenomenon have a variety of opinions on what its source might be.
As you'll see if you read the whole article, one theory is that this is evidence of certain regions of our universe having quantum entanglement with other universes, and if that turns out to be the case I would refer back to a recent entry I called The Fifth Dimension is Spooky. It seems that dark flow is very similar in nature to the dark energy that accelerates our universe's expansion and the dark matter that has held our universe together: I am proposing that all would appear to be evidence of different kinds of gravitational attraction from additional dimensions. Regular readers of this blog will recognize that this is not a new concept for me, but is rather one of the central ideas from my book. Another blog entry that explores this concept of how dark energy and dark matter are evidence for the existence of extra dimensions is Dark Gravity Across the Dimensions. Here's the video for that entry again:
A direct link to the above video is at http://www.youtube.com/watch?v=ZhGOgKIWBaQ
I was surprised to recall now that this blog entry looks at yet another article written by Marcus Chown: clearly I'm a fan!
Enjoy the journey,
Next: When we talk about dark flow, dark energy, and dark matter we're talking about something that is undetectable except for indirect evidence. Next time we'll take another tangential leap from that idea with an entry called "Nothing is Real".