New measurements cut dark matter in Milky Way by half
The uncertainty of science: New more robust measurements by Australian astronomers has shown that the amount of dark matter in the Milky Way galaxy is about half of what previous measurements had estimated.
Without doubt something is causing the outer stars in galaxies to orbit their galaxies at much greater speeds than they should. The answer that astronomers have posited since the late 1950s is that there is additional unidentified mass, dubbed dark matter, lurking as a halo around each galaxy, pulling on those outer stars and making them move faster.
The problem remains that no one has as yet detected this unidentified dark matter. Moreover, there are enormous uncertainties in the measurements of the motions of stars. This result helps narrow those uncertainties.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The uncertainty of science: New more robust measurements by Australian astronomers has shown that the amount of dark matter in the Milky Way galaxy is about half of what previous measurements had estimated.
Without doubt something is causing the outer stars in galaxies to orbit their galaxies at much greater speeds than they should. The answer that astronomers have posited since the late 1950s is that there is additional unidentified mass, dubbed dark matter, lurking as a halo around each galaxy, pulling on those outer stars and making them move faster.
The problem remains that no one has as yet detected this unidentified dark matter. Moreover, there are enormous uncertainties in the measurements of the motions of stars. This result helps narrow those uncertainties.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Silly Thoughts….
I’m no phyicist but the whole “dark matter” theory has never sat well with me. Maybe it’s just the term, dark matter, which sounds like something straight out of a Star Wars movie. Words have meanings, and I think that over the past several decades, while shunning the use of ependyomous names, scientists have gotten too cheeky and started using silly names. Gluons…really!? Why not call them clingons it’s so apropos?
When the names don’t fit the adgenda or narrative, they simply change them. For instance, global winter became global warming which then became climate changeand which is now being “trial ballooned” as climate disruption.
It’s all so silly and best fits in a Monty Python skit.
I agree with you Jwing, I remember one of my Astronomy professors calling Dark Matter one of the greatest failures of Astronomy in the 20th and now the 21st century.
As Bob points out there is a lot of uncertainty here. The fact that we so strongly cling to the idea of unseeable magic matter that makes up over half the universe after 70 years of no luck finding it starts to seem more like a act of faith than science.
But don’t dare suggest it might not exist because you will get all the people making money off the search for Dark matter ready to hunt you down with pitch forks.
“Dark Matter” is just a placeholder term to indicate the hypothetical things that would allow observation A to work consistently with observation B under the well understood laws of gravity.
I believe that term was chosen to be sufficiently vague so as not to connote any one particular possible answer. So maybe the “dark matter” was 40% neutrons and 60% black holes … or such other combination of difficult to observe stuff.
Astronomers would not be unhappy if galactic rotation curves where explained by a new fundamental force, (therefore negating entirely for “dark matter”).
Disclaimer: I am an Astronomer, but I don’t get any money from the super secret Dark Matter funding board.
Astronomers were really big on the idea of the either as well. We all know how that turned out.
And if you don’t believe there is big money in the search for Dark matter just look at the NSF search on Dark matter http://search.nsf.gov/search?access=p&output=xml_no_dtd&sort=date:D:L:d1&ie=UTF-8&btnG=Google+Search&client=NSF&oe=UTF-8&proxystylesheet=NSF2&site=NSF&q=dark+matter
But science ALWAYS about discovery and learning and never about collecting a pay check….
Monty Python skit indeed. When I learned of dark matter/dark energy/dark stars I realized this is the science equivalent of heaven / spirit realm. I am relieved to learn from the above comments that I am not alone in this Skepticism. non-evidence as a proof of the existence of non-matter.
I’m back in Sunday school learning of God and the angels in the invisible realm That now makes up 70% of our universe. I can’t see it, touch it, smell it, or interact with it in anyway. But if I have enough faith, the belief alone will make it real. I reject this line of thinking.
On the other hand, faith is necessary for religion, and interaction between people you rely on and your fellow man. It has no place in science or government.
Dark matter reminds me of when the question of equal parts of matter and antimatter was the discussion of the time. Out of all the thoughts and theories I heard, one stands out to me when a man said,”Matter and antimatter were created at the same universal event but would have canceled each other out had not antimatter also experienced anti-time separating the two and yet occupying the same space. This may be the quantum affect that we find in other energies such as gravitation and magnetics which as of yet are unexplained”.
One of these unexplained phenomenon is the Tides. During the new Moon when the sun and the moon are aligned.The strongest gravitational effect results in the highest “tides” possible.
The first problem is, Earth is in freefall and there should be very little effect experienced. Second, gravitational effect is in one direction and the tides are bi directional. There is no reason A tidal bulge should occur in the opposite direction from the gravitational effect.
Does the mass of the earth Block the gravitational effect? or is there an anti-gravity affect realized from the alignment of the sun and the moon? or is there another force yet unexplained that is occurring. (Here is a hint, the difference between the suns side tide and the far earth tide is 3%. This is the true gravitational effect Earth receives in freefall.)
My personal hypothesis is that the tidle affect is actually the result of gravity being reflected By the alignment of gravitons (for the lack of a better name) at 90° to the suns Gravitational pull. This means gravity is increased 360° around the planet Like squeezing a water balloon forcing the bulge to occur at the other two ends.
The polar regions of the earth are constantly in the region of the 90°, and this effect would explain why the barometric pressure and the atmosphere is the thinnest over the poles.
If someone wants a Nobel prize, simply take the barometric pressure on a six hour interval following the tides to see if there’s a change that is not weather related. If there is a change, this will prove the gravitational Reflection theory and change science. (And is the next clue in artificial gravity and antigravity creation)
As for why stars on the rim of the galaxy move faster than the stars in the middle, The ones on the outside are being held in check by the combined gravitational pull of the galaxy. Just as there is no gravity at the center of a planet, the gravitational pull in the center of the galaxy is canceled out. So a star with Inertia will always find its path to the outer rim where the combined gravity will counter its speed. The evidence for this is best in the Images of galaxy collisions. The stars on the outer regions are the ones flung into space when they come close to a counterbalancing rival gravity field.
Very astute comment with regards to dark matter and what Science wants us to believe, very much like the religion of global warming and Darwin’s theory of evolution. When dark matter comes up,(not much in my world) it is always THEY SAY!
Max,
I agree that “dark matter” is scientific hand waving, sort of like explaining why the Earth does not fall into oblivion by saying that the Earth rests upon the back of a giant turtle. And as Steven Hawking said in “A brief History of Time,” that turtle rests upon another turtle, and that it is turtles all the way down.
Yours are interesting thoughts, however, tidal effects are well understood. In high school physics classes, we learn that gravity pulls on the center of mass of a planet (or comes from the center of mass) in order to ease the calculations for orbits. We also only calculate orbits of one body (e.g. the moon) relative to one other body (e.g. the Earth) without considering the effects of some third body (e.g. the sun) because the calculation is too complicated – so complicated that no one has yet come up with a sole equation to solve for three bodies (there is a challenge that would likely earn a Nobel Prize, meanwhile we have to run simulations to solve for these cases).
The nature of gravity is that its effect becomes less with distance from the massive object that is the “source” of the gravity. As it turns out, planets are so large that the gravitational pull from the sun and especially the moon is appreciably greater on the sun or moon side of the planet and lesser on the far side. We people are not large enough to feel such an effect, even from the Earth (although, small as it is, it is there).
The near side is pulled harder than the center of mass, and the far side is pulled not as hard, the result is that, as seen from the center of mass, the near side looks like it is being pulled toward the sun or moon, and the far side looks like it is being pulled away. Bulging or tides occur when a planet is flexible. As you suggested, it is similar to tugging on two sides of a water balloon. (What happens when you hold a water balloon from its top, and what happens when the balloon is in free fall?) Thus the Earth bulges a little bit, but so do the liquid oceans, as they experience the very same effect, and we see this phenomenon as tides.
Unlike the Earth, the moon is solid throughout; otherwise it would bulge a bit from tidal forces, too. If the moon had oceans, then they would have tides that would have half-month-long periods (two high tides each month) due to the effects of the sun’s gravity and its monthly orbit about the Earth.
The mass of an object does not block gravitational effects. There is no “gravity shadow” that the moon passes through when it experiences an eclipse, as it did the other night. The gravitational influences on the moon from the sun continue even during such eclipses. All parts of the Earth and the moon are affected by the sun’s gravity, no matter how deep into the planet or how much material is between each part and the sun.
If the far side of the Earth were in a gravitational shadow, then the bulge on that side would be significantly larger than it is, as there would be no pull at all from the sun or the moon on that side. If you think about it, if such a shadow existed, then you would have to ask yourself, “How deep into a planet would the shadow become a complete shadow (how big would the planet/asteroid/space-station/object have to be in order to cast such a shadow)?” Is it thin, like a sheet of paper casting a shadow?
Once you answer that question, then you know how much of the Earth’s crust would have to endure all of the sun’s gravitational force that keeps the Earth in the sun’s orbit (or whether an astronaut in a space station stops orbiting the Earth in free-fall and can stand on the far-side of the station as if in partial or full Earth gravity). Could that much crust really withstand all of that force? Would the planet be pulled apart just from this force? And what would be the effect at the center of mass of the Earth – wouldn’t it fly off into space in a straight line, leaving the near-side crust to orbit the sun on its own?
Or maybe I should have just pointed out that the gravitational effects of the center of a mass are not cancelled by a shadow created by the outer layer of the mass. Otherwise gravity would not be a factor of mass but of “visible” surface area.
I for one do not believe is some mythical Dark Matter. At least not that its some new magic material or force.
For one every time a new more powerful telescope is put on line the scientists go “WOW the universe is bigger than we thought. This could change everything we thought before.”
Until they find the edge I’m just going to assume there is one out there someplace but its Way Way farther away than they thought and all the missing mater could be out there.
Think of it like this. I can hold my hand up in front of a billboard and take a picture.
Since you have no idea the size of my hand, the size of the bill board or the distance between everything you have no idea on how big any of them are.
You need any two of those measurements before you can estimate the third. And right now scientists are having a hard time measuring anything outside out solar system accurately.
All astronomers can do right now is take pretty picture and say “Oh look its, __________ than we thought.”
Hell right now they can’t even tell me if Pluto is a planet or a cartoon dog.