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The Milky Way Is Much Less Massive Than Previous Thought

Soulskill posted about 3 months ago | from the galactic-atkins dept.

Space 119

schwit1 writes: New research by astronomers suggests that the Milky Way is about half as massive as previously estimated. It was thought to be roughly the same mass as Andromeda, weighing in at approximately 1.26 x 10^12 solar masses (PDF). This new research indicates its mass is around half the mass of Andromeda. "Galaxies in the Local Group are bound together by their collective gravity. As a result, while most galaxies, including those on the outskirts of the Local Group, are moving farther apart due to expansion, the galaxies in the Local Group are moving closer together because of gravity. For the first time, researchers were able to combine the available information about gravity and expansion to complete precise calculations of the masses of both the Milky Way and Andromeda. ... Andromeda had twice as much mass as the Milky Way, and in both galaxies 90 percent of the mass was made up of dark matter."

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Tax Something (-1, Flamebait)

Anonymous Coward | about 3 months ago | (#47565927)

Something should be taxed to help offset this.

Re:Tax Something (4, Funny)

i kan reed (749298) | about 3 months ago | (#47565969)

You're right, please support HR-27-1337, placing a 200% tax on politicizing random science discussions.

Re:Tax Something (0)

Anonymous Coward | about 3 months ago | (#47566167)

A 200% tax on something worthless?

Re:Tax Something (1)

Shakrai (717556) | about 3 months ago | (#47567209)

You're right, please support HR-27-1337, placing a 200% tax on politicizing random science discussions.

I'd like to support your tax but I fear that the climate change discussions will see a massively improved signal to noise ratio with corresponding decrease in the eye rolling ratio.

Re:Tax Something (-1)

Anonymous Coward | about 3 months ago | (#47565999)

Damn Andromedans have been buying carbon credits off us and I haven't seen a dime! Gore, I'm looking at you...

Re:Tax Something (0)

Anonymous Coward | about 3 months ago | (#47569065)

You can always count on some humorless asshole to downmod. His mother must have forgotten his Lucky Charms during the last grocery run.

Re:Tax Something (1)

I'm New Around Here (1154723) | about 3 months ago | (#47570149)

You can always count on some humorless asshole to downmod. His mother must have forgotten his Lucky Charms during the last grocery run.

Worse. His asshole father ate all the marshmallows in one bowlfull.

Re:Tax Something (0)

Anonymous Coward | about 3 months ago | (#47570431)

Funny how they keep going back on forth on the mass of the galaxy. Previously, the Milky Way was thought to be about half as massive as Andromeda, then they say it's the same and now they are going back to saying it's half.

Sponsored by Mars Candies: (5, Funny)

i kan reed (749298) | about 3 months ago | (#47565947)

Try the milky way diet plan. You too can lose 1.3 quadrillion solar masses in just one month trying the Milky Way(TM) diet.

Check out these before and after shots: you can't even see the dark matter anymore.

Re:Sponsored by Mars Candies: (1)

jfdavis668 (1414919) | about 3 months ago | (#47566079)

What if I like Three Musketeers better?

Re:Sponsored by Mars Candies: (1)

roman_mir (125474) | about 3 months ago | (#47566091)

It's the inflation in play here, just like in the economy, the units of measurement are being stretched now, so the same mass measured in different units gives a nominally different answer ;)

Re:Sponsored by Mars Candies: (1)

smooth wombat (796938) | about 3 months ago | (#47566479)

It's the inflation in play here, just like in the economy, the units of measurement are being stretched now, so the same mass measured in different units gives a nominally different answer

A better example would be the sizing of women's clothes. What is now a size 4 used to be a size 6 a few years ago but because women are getting fatter, the sizes had to change to make people feel good about themselves.*

* Men don't have to worry as much because their sizes are measured in inches.

Re:Sponsored by Mars Candies: (1)

roman_mir (125474) | about 3 months ago | (#47566497)

* Men don't have to worry as much because their sizes are measured in inches.

- another type of Milky Way?

Re:Sponsored by Mars Candies: (1)

mythosaz (572040) | about 3 months ago | (#47567909)

* Men don't have to worry as much because their sizes are measured in inches.

Well, sort of.

Although more common in women's apparel, vanity sizing occurs in men's clothing as well. For example, men's pants are traditionally marked with two numbers, "waist" (waist circumference) and "inseam" (distance from the crotch to the hem of the pant). While the nominal inseam is fairly accurate, the nominal size may be smaller than the actual length by more than an inch in U.S. sizes. In 2010, Abram Sauer of Esquire measured several pairs of dress pants with a nominal waist size of 36 at different U.S. retailers and found that actual measurements ranged from 37 to 41 inches.[7] The phenomenon has also been noticed in the United Kingdom, where a 2011 study found misleading labels on more than half of checked items of clothing. In that study, worst offenders understated waist circumferences by 1.5 to 2 inches. London-based market analyst Mintel say that the number of men reporting varying waistlines from store to store doubled between 2005 and 2011.[8]

Men have been lying about a couple of inches in the pants forever too :)

Re:Sponsored by Mars Candies: (1)

TheCarp (96830) | about 3 months ago | (#47568827)

Well thanks for that. I was actually wondering recently why it was so hard to shop for pants. I have a hard size anyway, as I am built for a much smaller inseam than my waist (or rest of my torso) would seem to indicate. In fact, I would say if you look at my torso vs legs, I have the torso of someone several inches taller than me, and the legs of someone an inch or two shorter.

Looking back, I think this is why my childhood doctor was always suggesting my weight should be unreasonably low based on her height charts. I mean, she was right, I was overweight, but, not nearly by as much as she made it out, once I got into HS sports I found out her "ideal weight" for me based on height was about 10 lbs less than my lean body mass!

In any case, I find this makes pants shopping hard. Often over the years I have had to buy pants that were too long and then have the legs shortened, which is no help for inseam issues at all.

Re:Sponsored by Mars Candies: (1)

I'm New Around Here (1154723) | about 3 months ago | (#47570187)

Well thanks for that. I was actually wondering recently why it was so hard to shop for pants. I have a hard size anyway, as I am built for a much smaller inseam than my waist (or rest of my torso) would seem to indicate. In fact, I would say if you look at my torso vs legs, I have the torso of someone several inches taller than me, and the legs of someone an inch or two shorter.

My stepson was that way as a teenager. His mother had to buy jeans that fit his waist, then have them altered to remove the extra six inches of length from the legs. And that was with buying the shortest inseam available in the waist size.

Re:Sponsored by Mars Candies: (3, Interesting)

hairyfeet (841228) | about 3 months ago | (#47570203)

It AIN'T the men, its the stupid as hell clothing industry thinking any guy besides metrosexuals give a rat's ass about that. I don't know how many guys I've talked to the past few years that are ROYALLY PISSED that they can't just go into a store and grab a pair of size whatever and know it'll fit. We don't care if you call it a 37 or an ummagumma just STICK TO IT so we can just walk in and buy a pair of damned pants without having to try shit on like the girls...is that REALLY so much to ask for?

As for TFA? The correct answer is "we don't know shit, it'll probably change, but for now the number pulled out our collective asses is". hell they can't even make the math work without "dark" this and "dark" that which should automatically be replaced with a little stick figure shrugging its shoulders. I think the only thing we can truly say for certain is how things work in this one little teeny tiny itsy bitsy area, anything else? Its just wild guesses with a LOT of question marks in there.

Re:Sponsored by Mars Candies: (0)

Anonymous Coward | about 3 months ago | (#47566113)

10^12 is not a quadrillion.

Re:Sponsored by Mars Candies: (1)

i kan reed (749298) | about 3 months ago | (#47566181)

I always forget it's zero indexed.

Also, thanks to the reminder, I've decided that "zillion" most likely is equal to "thousand".

In Other News... (3, Funny)

cruff (171569) | about 3 months ago | (#47565987)

The Milky Way Galaxy was seen running off while crying about its impending demotion to dwarf galaxy status.

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Good news, everyone! (3, Funny)

ArcadeMan (2766669) | about 3 months ago | (#47566035)

The Milky Way is much less massive than previously thought

Good news for everyone who's lactose intolerant.

neverending WMD on credit holycost falling apart (-1)

Anonymous Coward | about 3 months ago | (#47566073)

a lot of stuff is; http://www.youtube.com/results?search_query=wmd+weather+media makes our fictional deities look like genocidal psychopaths? better days ahead.. momkind new clear options include spirit based compassion for ALL equally. what a notion... meanwhile we hang on to our hemispheres as our perception of time, space & circumstance becomes smaller?

Due to excessive bad posting from this IP or Subnet, anonymous comment posting has temporarily been disabled. You can still login to post. However, if bad posting continues from your IP or Subnet that privilege could be revoked as well. If it's you, consider this a chance to sit in the timeout corner or login and improve your posting. If it's someone else, this is a chance to hunt them down. (like textual predators?) If you think this is unfair, please email moderation@slashdot.org or sing a long time strong if you will http://www.youtube.com/watch?v=ug7IgB8MfWE the language of the heart is practically foolproof... see you there...

Dark? (1)

Pro923 (1447307) | about 3 months ago | (#47566075)

lHow can they possibly tell how much of the matter is "Dark"? I can get the idea of what they're doing - using the relative speeds of each local galaxy to determine the masses contained within each, but how could they possible determine how much mass in each galaxy wouldn't be seen by using light within the bounds of the visible spectrum?

Re:Dark? (1)

Anonymous Coward | about 3 months ago | (#47566119)

They measure the rotation curve - the orbital velocity at various distances from the galaxy's centre - and use those points to calculate the mass binding the orbiting stars. That give the total of dark + visible matter. The mass of normal, stellar matter is estimated from the star counts and knowledge of stars in our own galaxy.

Re:Dark? (1)

Daniel Oom (2826737) | about 3 months ago | (#47569799)

Now if the amount of normal steller mattter is known and the galaxy has only half the mass estimated earlier, that should make the amount of unexplained 'dark' matter a whole lot smaller....

Re:Dark? (0)

Anonymous Coward | about 3 months ago | (#47566209)

What makes you think we are bound to the visible spectrum? We have plenty of infrared/UV/radio telescopes.

Personally, I haven't ever understood why physicists say that the dark matter has to be something exotic and not simply particles of dust that aren't bound up in stars, but I assume they have discounted this explanation for a good reason.

Re:Dark? (5, Informative)

gurps_npc (621217) | about 3 months ago | (#47566293)

Dust blocks light and turns it into heat, which it radiates. So it shows up on infrared telescopes you mentioned.

Re:Dark? (0)

Anonymous Coward | about 3 months ago | (#47567443)

Dark matter is possible one of the worst things they could have ever called it.

I guess gravitational anomaly is too Star-Trecky.

Think of dark matter this way. The numbers doesn't add up.
If you pretend that you have a lot of gravity without actually having matter somewhere out there between the real matter then the numbers add up.

Re:Dark? (5, Informative)

Anonymous Coward | about 3 months ago | (#47567977)

All known stable forms of matter take only four forms: The lightest charged lepton, the electron, the lightest baryon, the proton, the nearly massless neutrinos, and atomic nuclei built from bound states of protons and neutrons. All but the neutrinos interact with matter in well-known ways that we can definitely measure (they are, or contain, electrically charged particles and therefore emit and scatter photons, which are relatively easily picked up). The neutrinos only undergo weak force interactions, but modern detectors can still pick them up. Their known number density and the limits on their mass mean they can't account for the observed gravitational binding of galaxies.

Any normal matter would interact with the light from objects behind it. This is the origin of effects such as the Lyman Forest which reveals the distribution of cold hydrogen in the flight path of distant light... The bottom line is, baryonic matter in the quantities implied simply has nowhere to hide. It's just too easy to detect ten times a galaxy's mass of matter sprinkled among the galaxy's visible part.

Hence the hypothesis of a particle which has mass but no electric charge, color charges or weak hypercharge. It would cast a gravitational shadow but otherwise be virtually undetectable since it does not undergo any interactions we can make individual particle measurements of. Hence the 'dark' in dark matter. One of the few alternatives to a dark particle is a universe suffused with low-mass black holes, but the lack of either microlensing events or gravitational waves emitted by their scattering off each other is difficult to explain. There are a few other places in GR that you can insert hypothetical terms without making it blow up in the face of observations - in fact Einstein's original cosmological constant very effectively explains accelerating expansion. It's also possible that GR isn't the correct theory of geometrodynamics, and the effect of higher-order curvature terms or such is not zero.

GR and QFT are fundamentally incompatible (GR is classical, QFT is quantum), so while there absolutely must be new physics out there, the question is where the new physics lays and what form it takes (and can we ever reach the energy levels to directly investigate it). The belief among physicists is that the correct theory should be the simplest one which fully explains observed phenomenon - Hence why, for example, GR as currently postulated does not involve any higher order curvatures - and the standard cosmological constant / cold dark matter framework does a remarkable job of explaining the evolution of the universe to its present state with remarkably few parameters.

Re:Dark? (1)

quixote9 (999874) | about 3 months ago | (#47569839)

Very lucid. Thanks for this. One of the things I've wondered is why it's not usually mentioned that "GR [may not be] the correct theory of geometrodynamics." I mean, why dark matter? Why not, "we don't understand gravity yet"? Or, we don't understand all the possible forces of attraction well enough? What about the Casimir Effect, for instance? What happens if that's somehow additive at cosmic scales? What if we've missed something? (Wouldn't be the first time.) It's probably very obvious that I am NOT any kind of physicist.

But you also sort of answered that. It would take a lot more ad hoc assumptions given our current understanding.

Re:Dark? (0)

grantspassalan (2531078) | about 3 months ago | (#47570169)

“What if we've missed something?”

The electric force is 10^36 times greater than gravity. Most humans, including physicists cannot really visualize a number with 36 zeros behind it. Because charges can either attract or repel, the electric forces in the universe ALMOST but not quite in some instances cancel each other. It is the ignoring of this tiny imbalance which is not being accounted for in the motion of the galaxies that causes astrophysicists to suggest the existence of dark matter, dark energy and black holes. None of these strictly mathematical constructs have ever been discovered to actually exist.

Re:Dark? (0)

Anonymous Coward | about 3 months ago | (#47571073)

“Most humans, including physicists cannot really visualize a number with 36 zeros behind it.

1,000,000,000,000,000,000,000,000,000,000,000,000

Wow, that was hard!

It's about the number of atoms in 11023 tons of mercury.

Re:Dark? (0)

Anonymous Coward | about 3 months ago | (#47571029)

Why not, "we don't understand gravity yet"?

This question is being actively researched by several groups at university physics departments, and parts of other gravity research groups. The problem is that even the researchers themselves admit at talks that the alternative gravity theories don't explain observations as well or as comprehensively as dark matter theories do. It is certainly of interest to mainstream physics, but it hasn't made any big breakthroughs yet. And as much the armchair physicists online complain dark matter theories is just an arbitrary fudge factor, the alternative gravity theories frequently end up being too arbitrary, e.g. with arbitrary scales where things just change to make it match observations better.

Re:Dark? (1)

penguinoid (724646) | about 3 months ago | (#47571401)

I mean, why dark matter? Why not, "we don't understand gravity yet"?

Because "we don't understand gravity yet" contains no data and makes no predictions (ie, it may well be true but it is unscientific). I think of dark matter as a list detailing exactly where and how much we don't understand gravity or cosmological particle physics. When someone wants to test a new theory of gravity, they will know where to check for discrepancies with GR by looking at where dark matter is; alternately, when someone wants to test a new theory for cosmological particle physics, they can test whether it produces dark matter in the appropriate places.

Re:Dark? (4, Informative)

gurps_npc (621217) | about 3 months ago | (#47566333)

It's not just the visible spectrum, it's all radiations levels.

Different amounts of mass result in different star types which give up different types of light. non-star objects - dust, planets, etc. block light and radiate out the energy they absorb as heat.

So by looking at any point, we can tell how much mass it has by the amount and type of light it gives off, including the non-visible spectrum, i.e. heat.

There are a few assumptions made, but it makes a lot of sense, mathematically.

None of it would have been possible before we understood the formulas behind fusion.

Re:Dark? (1)

Jeremy Erwin (2054) | about 3 months ago | (#47566431)

but how could they possible determine how much mass in each galaxy wouldn't be seen by using light within the bounds of the visible spectrum?

Such "dark matter" would show up on Xrays [harvard.edu] infrared [caltech.edu] or radio [nrao.edu] , so that's not a problem. If, however, the "dark matter" does not interact with electromagnetism, but only with gravity and the weak force, (which would be an extremely odd, and frankly, a not very believable aspect of cosmology) things would get a bit tricky.

Re:Dark? (4, Informative)

DM9290 (797337) | about 3 months ago | (#47566827)

If, however, the "dark matter" does not interact with electromagnetism, but only with gravity and the weak force, (which would be an extremely odd, and frankly, a not very believable aspect of cosmology) things would get a bit tricky.

That is EXACTLY what most of the dark matter is suspected to be and that is what makes it tricky.

Re:Dark? (0)

Anonymous Coward | about 3 months ago | (#47566901)

Nope, only gravity,

Re:Dark? (1)

geekoid (135745) | about 3 months ago | (#47569965)

"(which would be an extremely odd, and frankly, a not very believable aspect of cosmology"
says someone, every time something new is found.

Re:Dark? (0)

Anonymous Coward | about 3 months ago | (#47566589)

How can they possibly tell how much of the matter is "Dark"?

By simple observation [amazon.com]

Re:Dark? (1)

Anonymous Coward | about 3 months ago | (#47566685)

They estimate the amount of dark matter from the rotational speed of the galaxy. Basically, a rotating body is in equilibrium between the centripetal pseudo-force that wants it to spread out into an infinitely wide disk, and the binding force (gravity in this case) that wants it to be a perfect sphere. When you look at the amount of visible matter and attempt predict its shape from its rotational speed and mass, you realise the galaxy is the wrong shape. There must be an extra force pulling the stars together. That extra gravitational binding energy comes from dark matter.

Because there has to be so much of it, we're sure it's not just ordinary matter, because that amount of matter would've started to collapse under its own gravity, raising its temperature and pressure and causing it to glow. By definition we would be able to see that on some wavelength or another. Whatever's there must be unable to radiate electromagnetic radiation!

Re:Dark? (-1)

Anonymous Coward | about 3 months ago | (#47567391)

What makes you think the Milky Way is in rotational equilibrium?

Re:Dark? (0)

Anonymous Coward | about 3 months ago | (#47571091)

What makes you think the Milky Way is in rotational equilibrium?

What makes you think they can even accurately calculate the rotation of the galaxy if they're 50% off on the mass?

Re:Dark? (1)

PvtVoid (1252388) | about 3 months ago | (#47567047)

lHow can they possibly tell how much of the matter is "Dark"? I can get the idea of what they're doing - using the relative speeds of each local galaxy to determine the masses contained within each, but how could they possible determine how much mass in each galaxy wouldn't be seen by using light within the bounds of the visible spectrum?

You can see the light. So you do this: 1: Measure the mass of the galaxy. 2: Add up all the mass from the stuff you can see. Subtract (2) from (1).

Re:Dark? (3, Informative)

Anonymous Coward | about 3 months ago | (#47567095)

They've been mapping Dark Matter based on gravitational lensing. "Nothing" doesn't cause gravitational lensing, so we know something is there, and whatever it is, there is almost 10x more of it than what we can see in the entire EM spectrum from radio to gamma.

god particularly angry with boston? (-1)

Anonymous Coward | about 3 months ago | (#47566141)

cannot catch a break it seems? as if a tornado isn't enough? http://www.bostonglobe.com/metro/2014/07/30/boston-firefighters-are-battling-four-alarm-fire-east-boston/19yz9Ah6nRDDaO53wUsGWL/story.html

Misweighed (1)

Culture20 (968837) | about 3 months ago | (#47566185)

Astrophysicist kept his foot on the scale again.

Andromeda is a fattie! (1)

coinreturn (617535) | about 3 months ago | (#47566221)

Nyah, nyah.

Bi73h (-1)

Anonymous Coward | about 3 months ago | (#47566247)

(Click hEre [goat.cx]

It's okay Milky Way... (0)

Anonymous Coward | about 3 months ago | (#47566261)

... I'm not 1.26 trillion solar masses either :(

When the Milky Way and Andromeda galaxies collide (1)

jphamlore (1996436) | about 3 months ago | (#47566331)

Does the new estimate for the mass of the Milky Way galaxy change the expected dynamics when the Milky Way and Andromeda galaxies collide in about 4 billion years [nasa.gov] ?

Re:When the Milky Way and Andromeda galaxies colli (0)

Anonymous Coward | about 3 months ago | (#47566601)

Lookin' forward to meet hot andromeda chicks when I live till then.

Milky Way Now Fun Sized (1)

Anonymous Coward | about 3 months ago | (#47566343)

For your convenience.

Is this surprising? Twice as many stars (1)

buback (144189) | about 3 months ago | (#47566409)

I've been taught that Andromeda has approx. 2x as many stars as the Milky Way. I learned this years ago, as far as i can remember.

Is it really surprising news that a galaxy with twice as many stars is twice as massive? Were these researchers just fact-checking?

Re:Is this surprising? Twice as many stars (3, Insightful)

Bill, Shooter of Bul (629286) | about 3 months ago | (#47566513)

Well, to be fair, most of the mass is *not* in the stars, but the dark matter. It might be a reasonable inference that twice the stars would also mean twice the dark matter, but that might not necissarily be true.

Re:Is this surprising? Twice as many stars (1)

buback (144189) | about 3 months ago | (#47567295)

So then really what they are confirming is that inference; that matter and dark matter are in a 1/9 ratio, and that if our galaxy has x stars and Andromeda has 2x stars, then Andromeda will also have 2y dark matter mass to our y matter mass.

That seems to be a more interesting finding.

Re:Is this surprising? Twice as many stars (1)

buback (144189) | about 3 months ago | (#47567341)

*2y dark matter mass to our y dark matter mass*

It would be 18y dark matter to Milky Way y matter.

Yet another step (2)

necro81 (917438) | about 3 months ago | (#47566459)

Starting from the Earth getting kicked out from the center of the universe to the present hypothesis that visible matter is just a tiny fraction of all the stuff in the universe, having the mass of the Milky Way reduced is just another step in what Carl Sagan called The Great Demotions [google.com] . Hopefully by now humanity is getting used to it.

Start from scratch (0)

Marrow (195242) | about 3 months ago | (#47566553)

If they can be that wrong about something so fundamental, then how can they possibly claim to understand things or be right now?

I read an article recently about scientists saying the speed of light is not constant. Has their new variable speed of light calculation been plugged into all these other cosmology equations? Maybe this dark matter fudge factor would disappear and we would stop being wrong by the 1/2 the mass of a galaxy.

Re:Start from scratch (0)

Anonymous Coward | about 3 months ago | (#47567151)

c is fixed, but the speed of photons in space varies because space is not empty, even "empty" space is not empty, meaning light is traveling through a dynamic medium.

I am not sure that was what the article said (1)

Marrow (195242) | about 3 months ago | (#47567579)

http://www.sott.net/article/28... [sott.net]

I'm not sure that this is the same article, but it points out new measurements that may force us to alter the speed at very long distances to deal with quantum effects. (attenuation?)

http://beta.slashdot.org/story... [slashdot.org]

Re:I am not sure that was what the article said (0)

Anonymous Coward | about 3 months ago | (#47568639)

Maybe look at some the slashdot comments on that story (instead of rewriting thing here...), that theory is a curiosity at this point and even the paper it is proposed in says it is unphysical. The author thinks they can come up with a more complete version that isn't unphysical, but that is still to be seen. Even then, it is a an extremely small correction compared to the order of magnitude issues that dark matter theories are trying to address.

Re:Start from scratch (2)

Dragonslicer (991472) | about 3 months ago | (#47567799)

If they can be that wrong about something so fundamental, then how can they possibly claim to understand things or be right now?

It's not like they discovered that Andromeda is actually a 20-foot wide disco ball with funhouse mirrors making it look bigger than it really is. When you're talking about a branch of science that typically works in orders of magnitude, a factor of 2 is a pretty minor change.

Re:Start from scratch (0)

Anonymous Coward | about 3 months ago | (#47571127)

Cool, so they'll have no problem if we reduce their funding by a factor of 2 either.

Re:Start from scratch (1)

Anonymous Coward | about 3 months ago | (#47568113)

There is such a thing as degrees of wrong.

Using Newton's equations and constant gravity on a particle-in-a-vaccum to calculate that I'd be in freefall for 1.8 seconds if I were climbing and fell at the end of a 25 foot runout is "wrong" because I'm not a particle, I'm not in a vaccum, gravity isn't position independent, and one really ought to be using GR instead of Newton. But 1.8 seconds is close enough for the purposes of knowing how long until the rope starts to catch me.

Meanwhile you're acting as if knowing that x'' is not exactly equal to g means that you're free to suggest x'' = 2g... No, you're not, because that flies in the face of observation and is therefore stupid. Any proposed correction to a theory must agree with the original theory(ies), in the regime(s) where the original theory(ies) is/are known to be correct. Which is why for weak fields and low speeds, general relativity reduces to Newton's equations and any proposed replacement must do the same.

So no, observing that space might be dispersive at the parts-per-million level for the very highest energy photons detected does not mean you get to go "lolz stupid scientists have they plugged this into da equationz?!??" as if it somehow invalidates those equations. Any correction to or replacement for Relativity or QFT resulting from such an observation would necessarily also have to leave the vast body of observations that empty space is dispersionless at lower energies untouched.

Re:Start from scratch (1)

geekoid (135745) | about 3 months ago | (#47569873)

"I read an article recently about scientists saying the speed of light is not constant. "
scientist selling a book. Not scientists, and certainly not consensus.

And what do you mean so fundamental?

The mass of the galaxy seems fundamental (1)

Marrow (195242) | about 3 months ago | (#47570505)

But maybe its harder to measure MilkyWay than to measure the mass of other galaxies. Still, they cannot directly measure the mass of anything out there. So they are implying the mass by looking at the light coming from them and from neighboring objects. I would rather look forward to them being proven wrong about their assumptions because we would learn more. Maybe they might learn something that could help us out here on Earth.

So I prefer to look at theories which challenge the accepted science in the hopes that new discoveries might spark new technologies here at home.

Why is the Local Group moving closer? (1)

Khomar (529552) | about 3 months ago | (#47566581)

The article says that most of the galaxies are moving apart, but the Local Group is moving closer. Why would the local group be different than the other galaxies? Are there other groups of galaxies that are seeing the same effect, or is the Local Group an anomaly?

Re:Why is the Local Group moving closer? (4, Informative)

PvtVoid (1252388) | about 3 months ago | (#47567077)

The article says that most of the galaxies are moving apart, but the Local Group is moving closer. Why would the local group be different than the other galaxies? Are there other groups of galaxies that are seeing the same effect, or is the Local Group an anomaly?

The galaxies in the local group are close enough together to be a gravitationally bound system, and are therefore "decoupled" from the expansion. This is true of any cluster of galaxies, and there are many, many examples of such systems in the universe.

It's the same reason your body doesn't get bigger as the universe expands: the binding forces holding it together are stronger than the (tiny) force pulling it apart due to cosmological expansion.

Re:Why is the Local Group moving closer? (0)

Anonymous Coward | about 3 months ago | (#47567491)

It's the same reason your body doesn't get bigger as the universe expands: the binding forces holding it together are stronger than the (tiny) force pulling it apart due to cosmological expansion.

Crap, there goes my theory about the expansion of my waistline.

Re:Why is the Local Group moving closer? (1)

grep -v '.*' * (780312) | about 3 months ago | (#47568739)

your body ... gets bigger as the universe expands

So THAT'S why I'm so fat -- and here I was afraid it was somehow my fault. Sure glad to hear it's not.

Pass me that last piece of pie, would you?

Re:Why is the Local Group moving closer? (1)

geekoid (135745) | about 3 months ago | (#47569953)

"Pass me that last piece of pie, would you?"

No. Lose some weight.

Re:Why is the Local Group moving closer? (1)

budgenator (254554) | about 3 months ago | (#47571103)

I'd assume that all galaxy groups are Gravitationally bound, and when looking at the group you're in, the galaxies would appear to be closing, while the other groups would appear to be opening; this is an effect of Hubble's law, everything is moving away from any observer at 67.80±0.77 (km/s)/ Mpc, thus the farther away, the faster it is going away no matter where you are . Even at that, I've seen several Hubble images showing galaxies colliding just like we're about to do with Andromeda.

Oh no! (0)

Anonymous Coward | about 3 months ago | (#47566653)

That means there's less resources out there??

Guys! Cancel the self-replicating 3D printing asteroid colonies! Looks like we'll have to make do on *this* rock!

85% of gravity is caused by Dark Energy and Matter (0)

Anonymous Coward | about 3 months ago | (#47566661)

They are still way off.

accurate or precise? (0)

Anonymous Coward | about 3 months ago | (#47566771)

researchers were able to combine the available information about gravity and expansion to complete precise calculations of the masses of both the Milky Way and Andromeda

Precision is not useful here. What we need is accuracy, and it sounds like it was the accuracy that was improved, not the precision.

Also, let's take this new data with a grain of salt. The last scientist also claimed their measurements were accurate (though it's likely these new measurements are more accurate than the previous ones).

The sum total mass of previous thought = zero (1)

uCallHimDrJ0NES (2546640) | about 3 months ago | (#47566777)

Therefore, the Milky Way's mass is less than zero. What a difference an "-ly" makes. They should have sent their words to Lolly's.

Re:The sum total mass of previous thought = zero (1)

I'm New Around Here (1154723) | about 3 months ago | (#47570357)

I think I might be the only one to get that.

Meet you at the grocery store.

With this dark matter thing (1)

azav (469988) | about 3 months ago | (#47566833)

Is it possible that other stars are just hidden behind other stars and that contributes to a large portion of the missing mass?

Re:With this dark matter thing (1)

Anonymous Coward | about 3 months ago | (#47568019)

It's possible. The probability that a given star is behind any star is about 10^-15. To get a large portion of the Milky Way stars behind other stars, we're talking about a probability of about 10^-1500000000000.

Re:With this dark matter thing (1)

painandgreed (692585) | about 3 months ago | (#47570017)

Is it possible that other stars are just hidden behind other stars and that contributes to a large portion of the missing mass?

No. If hidden by dust, we'd see more infrared heat in space as light emitted by stars has to go someplace. If hidden directly behind other solid objects (besides being so astronomically against the odds that things are only hidden from us), it wouldn't account for observations of galaxies rotations speeds that we see along the axis of rotation rather than against the edge. Even for the galaxies we see on edge, if they were all weighted with the mass on the other side of where we are, the rotations speeds, lensing, and other observational data would be different than what we see.

Don't think that dark matter is some quick answer to explain things away. All the obvious choices such as "it's all normal matter behind other normal matter", "it's just non-radiating normal matter", or "the laws of gravity might be different on the galactic scale" have all been suggested, tested, and found not to hold up first. Dark matter is the only real solution left standing at this point and the astronomers and scientists of the world had to be drug to that conclusion, kicking and screaming, over the decades, long before the public started hearing about it.

Re:With this dark matter thing (1)

I'm New Around Here (1154723) | about 3 months ago | (#47570437)

Dark matter is the only real solution left standing at this point and the astronomers and scientists of the world had to be drug to that conclusion, kicking and screaming, over the decades, long before the public started hearing about it.

Maybe if the ones who started talking about it had used a diffrerent term than "dark matter", it would be easier to accept. We hear about quarks, leptons, muons, and things with spin and flavor, etc. I don't understand all that, since I am not a scientist, but I can believe it is serious. Calling it "dark matter" was a dumb move, because it makes it sound as believable as "pixie dust" or "magic beans". At least, they could have used the Japanese words for it like they did with "tsunami".

New name (5, Funny)

gmuslera (3436) | about 3 months ago | (#47566909)

Marketing suggested that now it should be called the Skim Milky Way.

Re:New name (0)

Anonymous Coward | about 3 months ago | (#47567287)

"Marketing suggested that now it should be called the Skim Milky Way."

It's not that smaller, it's more like Half Fat Milky Way.

What about the supermassive black hole? (1)

dicobalt (1536225) | about 3 months ago | (#47567289)

Did they add the mass of the supermassive black hole at the center of the galaxy?

Re:What about the supermassive black hole? (1)

wierd_w (1375923) | about 3 months ago | (#47567559)

I am more interested in radical ideas, like anti-mass, being at work.

Say you have a large aggregation of mass that is orbiting a large, semistationary singularity-- like, a galaxy does.

Outside this rather bumpy gravity well, you have a diffuse cloud of antimass, which then pushes on, and chases the mass as it rotates around the central mass. This pushing cancels out the centripetal force.

It's an interesting idea, as it was recently postulated that there is no real compelling reason for antimass to not exist-- it is a perfectly valid solution in some circumtances-- meaning that the stuff may very well exist.

It would be interesting to see a reinterpretation of the data of for "dark matter maps" of the universe, with antimass pressure substituted for mystery gravity application-- even if the math doesnt add up.

Re:What about the supermassive black hole? (1)

geekoid (135745) | about 3 months ago | (#47569929)

Since E=mc2, have a negative mass would mean negative energy.

How do you have negative energy content?

Re:What about the supermassive black hole? (1)

tomhath (637240) | about 3 months ago | (#47567571)

Yes, but it turns out to be only a Mediocre Massive black hole

Re:What about the supermassive black hole? (0)

Anonymous Coward | about 3 months ago | (#47567695)

This is a gravitational study so every form of mass is already accounted for. The supermassive black hole is only 4 x 10^6 solar masses anyway. It's like worrying about the impact of a flea on the weight of an elephant.

Does Dark Matter really exist? (1)

Martin S. (98249) | about 3 months ago | (#47567881)

While it has been widely accepted in recent years that Dark Matter fixes the standard model. Increasing problems suggest that Dark Matter might not actually exist [dailygalaxy.com] .

Re:Does Dark Matter really exist? (0)

Anonymous Coward | about 3 months ago | (#47570409)

I read that article. There's nothing new there. It says that this physicist believes that Einstein's equations are wrong or that our understanding of gravity is flawed. Since the moment we first measured the rotational speeds of nearby galaxies, plugged the numbers into general relativity and noticed a vast difference between the expected result and the observed result, the possibility that Einstein's theory is as flawed as Newton's has been on the table. Unfortunately, no one's come up with anything better. String theory was hoped to do the job but it's incomplete and, so far, completely untestable. The study of theoretical physics, these days, is all about improving on Einstein.

There are only two possibilities. Either most of the mass in the universe is completely invisible and unable to be interacted with or Einstein's formula is merely a good approximation on the nature of gravity at really large distances but falls apart when you start dealing with the huge distances and/or masses at the galactic scale. While it seems more likely that Einstein is flawed his formulas work so very well for everything else and, in fact, work just fine when you treat dark matter as particles with mass but none of the other characteristics of matter.

This article doesn't provide any actual insight into what dark matter is. The physicist seems to think that our concept of gravity is wrong, which is possible, but if your going to make a claim like that you should at least have something else that does the job in the works.

Literally everything about humanity (0)

Anonymous Coward | about 3 months ago | (#47567885)

is much less than expected. You guys act like you are hot shit and you can't even leave your own gravity well as a species. You don't even have a base on your nearest astral body. Hell, you still fight over imaginary things like which religion is better. Humanity, get over yourself, you aren't that great.

Re:Literally everything about humanity (0)

Anonymous Coward | about 3 months ago | (#47568003)

Hey man, we have a condition! It's genetic!

Shouldn't That Be (0)

Anonymous Coward | about 3 months ago | (#47567903)

The Milky Way Is Thought To Be Much Less Massive Than Previous Thought

Gravity? How about magnetic fields?... (1)

Grow Old Timber (1071718) | about 3 months ago | (#47568543)

Helioshperes as well as our own Ionosphere (magnetic field) have shown that magnetism is a universal force to be reckoned with. Indeed gravity could be just a magnetic effect on an atomic scale. The more mass the more effect. Electrons pulsing in a atom synchronizing with identical atoms become a united energy. That's what holds things together. And what gravity is, basically. A united atomic force. Too simple? .

Re:Gravity? How about magnetic fields?... (0)

Anonymous Coward | about 3 months ago | (#47570467)

If a magnetic field was holding Jupiter in orbit or holding you to the ground it would be very detectable.

Kevin Sorbo will be pissed... (2)

Lumpy (12016) | about 3 months ago | (#47568629)

The commonwealth is a lot smaller than expected!

Yes, I went there.... Deal with my vast knowledge of really bad SciFi!

Re:Kevin Sorbo will be pissed... (2)

geekoid (135745) | about 3 months ago | (#47569941)

OTOH, Quark's garbage route will be shorter.

I saw your bad SCI-F, and raised you :)

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