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Milky Way Is Being Pushed Across the Universe (cnn.com)
dryriver quotes a report from CNN: Our home galaxy, the Milky Way, is being pushed across the universe by a large unseen force, according to new research. Although it may not seem like a friendly gesture, the newly discovered Dipole Repeller is actually helping our galaxy on its journey across the expanding universe. Researchers have known that the galaxy was moving at a relative speed for the past 30 years, but they didn't know why. "Now we find an emptiness in exactly the opposite direction, which provides a 'push' in the sense of a lack of pull," said Brent Tully, one of the study authors and an astronomer at the Institute for Astronomy in Honolulu. "In a tug-of-war, if there are more people at one end, then the flow will be toward them and away from the weaker side." But this is no aimless journey of motion. Researchers have long believed that our galaxy was attracted to an area rich with dozens of clusters of galaxies 750 million light-years away, called the Shapley Concentration or Shapley Attractor. "We found a flow pattern reminiscent of streams of water that are organized by gravity to run downhill," Tully said. "In detail, we played a mathematical trick by inverting the sense of gravity to see where flows would terminate in this altered case. Flows ended at our Dipole Repeller."
If I understood this right they are calling the lack of attraction, repulsion. There's no negative force, or dark energy style shit involved. Shouldn't they call it a non-attractor unless they show active repulsion? If I drop an object and it moves towards the ground I am not going to say my hand repelled it.
What does this even mean in a non-teleological universe?
"We're moving in the direction gravity is pulling us."
Sheesh, evil *and* a jerk. -- Jade
This is what I read from the original article. To my very limited ability to understand, it seems that "Km s-1" is a speed, not a distance. As stated, by the way, a few words earlier in "V CMB = 631±20kms1". Surely I am wrong. Or maybe they are.
Sent as ripples into the electromagnetic field. No single photon has been harmed in the process.
I think space itself is some kind of medium and not necessarily matter based. Currently, its composition is unknown. You can call this medium aether if you like, just do not confuse it with the luminiferous aether. There are several aether theories out there, one of the popular ones is the Superfluid Vacuum Theory.
Now, back to gravity. We know since Einstein that matter curves/disturbs space**. So, this medium, which is disturbed by matter, wants to be 'smooth' and it exerts a force on matter. This force is obviously a push force and we call it gravity.
From our perspective there is no way to differentiate between pull or push. Maybe until now.
** I know that according to GR gravity is a curvature of space-time and not just space. But if space itself is some kind of medium then the time dimension simply does not exist. What happens is that the disturbance of space prevents matter particles to interact with each other. We perceive this lack of interaction as if 'time' slow down since there is no change (We can only perceive 'time' by observing change). This picture is compatible with GR since relativity between moving bodies through space remains. However, it establishes a distinguished reference frame which is space itself.
Government cannot make man richer, but it can make him poorer. - Ludwig von Mises
if there were, it should have been called "Shapely Attractor".
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
... love!
So say we all
Oh please, that's just marketing. Remember "Greenland"?
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
If you read the article, you can find in less then 30s that its relative to background radiation.
"Now we find an emptiness in exactly the opposite direction, which provides a 'push' in the sense of a lack of pull," said Brent Tully, one of the study authors and an astronomer at the Institute for Astronomy in Honolulu. "In a tug-of-war, if there are more people at one end, then the flow will be toward them and away from the weaker side."
But ... that doesn't mean the weaker team is 'pushing', does it?
(facepalm)
No sig today...
If humans want to build a highway, they just build it and don't bother too much about the disruptions and dislocations caused. Despite what you might have heard about them sneakily filing a redevelopment plan and filing it in a dark basement guarded by leopards, in reality they move the entire galaxy away before embarking on such a project. We are just beginning to understand them.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
We should add warning labels to all our physics books that Relativity is "just a theory" and give equal time to alternative explanations,like the "Intelligent-falling-ism"
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
You've stumbled onto the wrong site, this is the site you are looking for: https://www.reddit.com/
Mod +1. This is the second or third time I've seen summaries of the press announcement, and the first time it has been even obliquely acknowledged that the so called "repeller" is nothing more than a localized lack of PULL, not any sort of actual gravitational "push". -1 to the article itself for being misleading bullshit and creating a "dipole" like an electron and an electron hole create a "dipole" in a uniform neutral metal, no more.
Surely there is nothing surprising about this. People have been doing cosmological simulations for a LONG time with a large number of pointlike objects interacting with GMm/r^2 attractive forces but to simulate galactic evolution and universal evolution from the big bang. The interesting point being that in the center of a uniform mass distribution, there is no net force but nevertheless 1/r^2 forces with any kind of inhomogeneity in the underlying free mass distribution tends to accrete in some places and abandon others, especially if it can inelastically interact and clump together into bound subsystems. This must have been seen in simulations pretty much every time, and should come as no surprise in nature.
Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
Great name for a band.
Right! And what we call light bulbs are actually dark suckers. They suck in the dark so you end up with light left over.
-- ssoorrrryy,, dduupplleexx sswwiittcchh oonn.. -Quote found on actual fortune cookie.
The approach being used that identifies the repulsor is a valid one. Bicycle mechanics have been using it since at least 1890 in practical work.
When truing a bicycle wheel, it makes sense to talk about the push that a spoke exerts against the ground that keeps the wheel from collapsing. While you cannot push a string, the tensile pulling forces of all the spokes toward the top of the wheel are too complex to easily analyze. But fortunately it works out that you can invert your frame of reference and then not worry about those forces since in the inverted framework those tensile pulling forces become a single push through the one spoke that opposes the sum of the vectors of all the other spokes.
A miniaturized bicycle mechanic standing on the inside surface of a wheel's rim could use this pushing vector to figure out where the hub of the wheel was. That is never done only because bicycle mechanics are big enough to eyeball the entire wheel. But scale the metaphor up....
That is what is being done here. It is an interesting study, and much more than a theoretical sleight of hand. It suggests that the Milky Way is moving away from a specific point, which they are calling the "Dipole Repulsor", but which can also be described as the Center Of The Big Empty. I did not see anything in the article that suggests that we know how far away the COTBE is, but it looks like we at least know its direction from Earth, the Solar System, and the Milky Way. That's more than we knew before.
It has long been understood that the universe is expanding like the surface of a balloon that is being inflated. This work suggests that we may now know the direction to the center of the (possibly local) universe. I'm not entirely sure of the scale of the implications... this could be on the scale of the Copernican Revolution.
Right! And what we call light bulbs are actually dark suckers.
You can joke if you wish, but in physics you may have heard of something called a "frame of reference," which specifies the default state you assume. That's not quite analogous to what TFA is doing, but it's something like that.
Newtonian physics assumes a default frame of reference that has no forces in it. Hence, we only talk about forces "existing" when they are non-zero.
But this "no forces" frame of reference doesn't really make sense when talking about the universe on large scales. Instead, the default state of the universe is a general curvature of space-time that galaxies exist within. You could perhaps think of it has a general "slope" on the rubber sheet model of spacetime. Or, if you insist on the tug-of-war analogy, the "default" state is with a certain level of tension. If you grew up as part of a "rope" within a universe like that, you'd probably develop a system of physics where the default "frame of reference" included tension forces pulling at you on both sides.
Anyhow, the "push" and "pull" and gravity doesn't quite make sense in terms of our normal analogy of grabbing onto something and physically pushing or pulling it. Rather, thinking of spacetime as curved, we change the slope. In the case of TFA, we have the default "slope" that pervades the universe, and previous research says our galaxy is moving in direction X more than the slope would suggest due to increased curvature in that direction. But it turns out there's also decreased curvature in another direction, which effectively decreases the threshold of the "default slope" in that direction.
If you lived as a "rope" in a continuous tug-of-war game since the beginning of time, which mostly had a default "tension" pulling at you from all sides... then you'd likely perceive a decreased tension as a "push" too. Since the whole "push/pull" thing is a bad analogy for gravitational spacetime curvature on a cosmic scale anyway, I'm not sure why everyone here is making fun of a bad analogy while upholding their bad analogy. They're both seriously flawed in this case.