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(Quanta Magazine)   Dark matter doesn't matter   (quantamagazine.org) divider line
    More: Obvious, Dark matter, Universe, Gravitation, Physical cosmology, General relativity, intangible form of matter forms, dark matter, tight cohesion of galaxies  
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1347 clicks; posted to Geek » on 01 Aug 2020 at 6:15 PM (1 day ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook



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1 day ago  
The modified gravity theories start to sound like the premise for the Zones of Thought
 
1 day ago  
If dark matter was matter I could blame my weight gain on it.
 
1 day ago  
I was a bit bummed out when SyFy cancelled it. But ultimately, subby is right. I got over it fairly quickly.
 
1 day ago  
"Dark matter is a fudge factor added without concrete evidence to make theory work with observations. This is absurd and unjustifiable. Instead, let's create a theory with many more unsubstantiated inventions to get around this ridiculous theory!"
 
1 day ago  
Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?
 
1 day ago  

New Farkin User Name: "Dark matter is a fudge factor added without concrete evidence


Fark user imageView Full Size
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


The question doesn't really make sense. The Universe started at the location of the Universe. It was small, then got bigger
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


It's equally everywhere, because the universe is expanding equally everywhere. This is like asking what point on a surface of a balloon the expansion started.
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


The "origin" is not anywhere in 3D space at the present time T=0 (the current universe).

It is in the past, at T = -13.8 BY in 4D spacetime.
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


It started everywhere, the singularity indicates the point in time where everything was in one place.
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


Fark user imageView Full Size
 
1 day ago  

New Farkin User Name: "Dark matter is a fudge factor added without concrete evidence to make theory hypothesis work with observations. This is absurd and unjustifiable. Instead, let's create a theoryhypothesis with many more unsubstantiated inventions to get around this ridiculous theory hypothesis!"


FTFY
 
1 day ago  

Marcus Aurelius: If dark matter was matter I could blame my weight gain on it.


Nothing can resist the attraction of the Taco Bell Hole.
 
1 day ago  

Spermbot: New Farkin User Name: "Dark matter is a fudge factor added without concrete evidence to make theory hypothesis work with observations. This is absurd and unjustifiable. Instead, let's create a theoryhypothesis with many more unsubstantiated inventions to get around this ridiculous theory hypothesis!"

FTFY


You really didn't
 
1 day ago  

covfefe: lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?

It's equally everywhere, because the universe is expanding equally everywhere. This is like asking what point on a surface of a balloon the expansion started.


Yeah but inside the balloon theres a 3d point where its the middle.
 
1 day ago  

lolmao500: covfefe: lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?

It's equally everywhere, because the universe is expanding equally everywhere. This is like asking what point on a surface of a balloon the expansion started.

Yeah but inside the balloon theres a 3d point where its the middle.


The balloon's middle is not anywhere on its surface, and our middle is nowhere in our 3-dimensional space. It's somewhere out there... (waves hands pointing toward some direction at right-angles to reality).
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


The Universe didn't start anywhere. It wasn't an explosion from a central point, it is an expanding realm of spacetime. There is no center of the Universe because everywhere is the center.

Or think of it like this: The galaxy clusters aren't moving away from each other. Rather, the space between the galaxies is filling up with more space, pushing them away. And this filling up of space is uniform, such that the farther away a galaxy is, the faster it is moving away from us.

And this perspective is observable anywhere in the Universe. Because everywhere is the center.
 
1 day ago  

lolmao500: covfefe: lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?

It's equally everywhere, because the universe is expanding equally everywhere. This is like asking what point on a surface of a balloon the expansion started.

Yeah but inside the balloon theres a 3d point where its the middle.


Space itself is expanding. The Big Bang isn't like a bomb that went off somewhere and we're all shrapnel. Its more like traffic in your city that's getting worse over the years, it didn't have a specific car that slowed down first.
 
1 day ago  

covfefe: lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?

It's equally everywhere, because the universe is expanding equally everywhere. This is like asking what point on a surface of a balloon the expansion started.


This is why I think I'm the center of the universe.
 
1 day ago  
"The stars are matter. We're matter. But it doesn't matter."

- Don Van Vliet

external-content.duckduckgo.comView Full Size


Captain Beefheart
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


In the center
 
1 day ago  

big pig peaches: This is why I think I'm the center of the universe.


You ARE the center of the Universe. And so am I. And so is Mars and Alpha Centauri and the Milky Way.

There is no center because everywhere is the center.
 
1 day ago  

New Farkin User Name: "Dark matter is a fudge factor added without concrete evidence to make theory work with observations. This is absurd and unjustifiable. Instead, let's create a theory with many more unsubstantiated inventions to get around this ridiculous theory!"


I think what they've come up with is not a theory (yet) but a hypothesis. Whether or not it replaces dark matter as the leading explanation depends on well it can fit with observations and if it can make any predictions that can be tested.
 
1 day ago  
How many licks does it take to get to the center of the universe?
 
1 day ago  

New Farkin User Name: lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?

The question doesn't really make sense. The Universe started at the location of the Universe. It was small, then got bigger


The difference is that the surface of an expanding balloon (where every part is expanding from every other part equally) is a 2D structure "mapped" on a 3D volume that is "inside" that 2D surface. That interior is not accessible from the 2D surface.

The expanding Universe (where every part of it is equally expanding from every other part, like raisins in a loaf of baking bread) is a 3D structure. For the analogy to hold, It is presumably mapped onto a 4th physical dimension "inside" or interior to that 3D surface not accessible from the 3D surface.
 
1 day ago  
This doesn't belong here, but Fark had no thread for it - for anyone who is interested, the SpaceX Crew Dragon capsule Endeavour, with Bob and Doug aboard, successfully undocked from the ISS around 7:30 pm EDT today.

Splashdown is expected around 2:42 pm EDT on Sunday, Aug. 2, just off Pensacola, Florida, to conclude the Demo-2 mission.

We now return you to your regularly scheduled thread.
 
1 day ago  

bingethinker: How many licks does it take to get to the center of the universe?


One can imagine the teeny tiny inhabitants of a point on the surface of a 2D balloon surface reaching the 3D center of the space inside the balloon by making a tiny hole and traveling through the skin of the balloon into that 3rd dimension.

One can imagine by analogy someone in our 3D universe doing the same.

But doing the former destroys the dynamic support of the balloon's surface. IOW, pop it at a point and the entire balloon disappears.

So we might like to think long and hard before we experiment with popping the "skin" of our 3D universe to see what is "inside."
 
1 day ago  

lolmao500: covfefe: lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?

It's equally everywhere, because the universe is expanding equally everywhere. This is like asking what point on a surface of a balloon the expansion started.

Yeah but inside the balloon theres a 3d point where its the middle.


Don't listen to the fark armchair-physicist brigade.  It started in Subby's Mom's knickers.
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


Fark user imageView Full Size


/robe
//wizard hat
 
1 day ago  

bingethinker: How many licks does it take to get to the center of the universe?


Just one.

Fark user imageView Full Size
 
1 day ago  

New Farkin User Name: "Dark matter is a fudge factor added without concrete evidence to make theory work with observations. This is absurd and unjustifiable. Instead, let's create a theory with many more unsubstantiated inventions to get around this ridiculous theory!"


There's a huge amount of observational evidence for dark matter.  And it comes from using many different theoretical frameworks (newtonian mechanics, general relativity, thermodynamic considerations, etc).  Dark matter has been around as a theory for a long time, and it keeps on explaining newer and newer observations that it wasn't originally specifically designed to explain.  But it keeps working because it seems to really be a thing.

And Dark Matter isn't some crazy thing that's super exceptional.  It's just a form of matter that doesn't reflect light very well and (mostly) interacts through gravity.  That's not something insane - known particles like neutrinos have similar properties (although neutrinos themselves as dark matter is not a very popular theory).

So Dark Matter is just some common particle that lives mostly outside of galaxies and has many properties that are similar to neutrinos.  The fact that there's probably a particle out there that we don't know about isn't some crazy idea.

Meanwhile, modified gravity theories keep getting fine tuned to hell to explain an observation or two, but then immediately fall apart anything new comes in and have to be retweaked for pretty much every new type of observation.
 
1 day ago  
MOND is a math exercise without any idea of a physical reality behind it. Still can't explain the Bullet cluster. So, whatever.
 
1 day ago  

lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?


time is the measurement of relative motion and everything is in motion in the eternal present

there was no beginning there will be no end
 
1 day ago  
yesterday is history
tomorrow is a mystery
thats why today's the present
its a gift to you and me
 
1 day ago  

zepillin: there was no beginning there will be no end


If there was no beginning and no end, you would not be here.
 
1 day ago  

pup.socket: zepillin: there was no beginning there will be no end

If there was no beginning and no end, you would not be here.


Why wouldn't I be
 
1 day ago  

zepillin: pup.socket: zepillin: there was no beginning there will be no end

If there was no beginning and no end, you would not be here.

Why wouldn't I be


Because if there was no beginning, an infinity of time would have to pass before you appear, and an infinity will never pass.
 
1 day ago  

zepillin: pup.socket: zepillin: there was no beginning there will be no end

If there was no beginning and no end, you would not be here.

Why wouldn't I be


I'm just Stardust in motion
 
1 day ago  

pup.socket: zepillin: pup.socket: zepillin: there was no beginning there will be no end

If there was no beginning and no end, you would not be here.

Why wouldn't I be

Because if there was no beginning, an infinity of time would have to pass before you appear, and an infinity will never pass.


That makes no sense I'm out of here
 
1 day ago  
i kan tiping jif
 
1 day ago  

zepillin: zepillin: pup.socket: zepillin: there was no beginning there will be no end

If there was no beginning and no end, you would not be here.

Why wouldn't I be

I'm just Stardust in motion


Maybe you are, but without a beginning and an end, you'd still have to wait for an infinity for stardust to appear, and that is waiting forever.
 
1 day ago  

Ishkur: lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?

The Universe didn't start anywhere. It wasn't an explosion from a central point, it is an expanding realm of spacetime. There is no center of the Universe because everywhere is the center.

Or think of it like this: The galaxy clusters aren't moving away from each other. Rather, the space between the galaxies is filling up with more space, pushing them away. And this filling up of space is uniform, such that the farther away a galaxy is, the faster it is moving away from us.

And this perspective is observable anywhere in the Universe. Because everywhere is the center.


If the rate of the expansion of space is constant, then why aren't all galaxies moving away from each other at a constant speed? Or is the expansion rate of space increasing?
 
1 day ago  

Spermbot: Ishkur: lolmao500: Can anyone answer me this : do we know where in the universe the universe started? Like where was the singularity? Or its not in our observable universe? Or we just don't know?

The Universe didn't start anywhere. It wasn't an explosion from a central point, it is an expanding realm of spacetime. There is no center of the Universe because everywhere is the center.

Or think of it like this: The galaxy clusters aren't moving away from each other. Rather, the space between the galaxies is filling up with more space, pushing them away. And this filling up of space is uniform, such that the farther away a galaxy is, the faster it is moving away from us.

And this perspective is observable anywhere in the Universe. Because everywhere is the center.

If the rate of the expansion of space is constant, then why aren't all galaxies moving away from each other at a constant speed? Or is the expansion rate of space increasing?


Yes.
 
1 day ago  

Spermbot: If the rate of the expansion of space is constant, then why aren't all galaxies moving away from each other at a constant speed? Or is the expansion rate of space increasing?


Couple things:

First: Yes, the expansion of the Universe is accelerating. At some point in the future it will be expanding faster than the speed of light, at which point distant galaxies will blip out of existence, being beyond our ability to observe them.

Secondly: This expansion of space is uniform everywhere, but the reason why it seems distant galaxies are moving away faster is because it's not the galaxies that are moving. It's the space between them that is filling up with more space, like raisins in a loaf of bread. The more space between us and a galaxy, the greater the expansion.

Simple analogy: Say all galaxies are moving away from us at a rate of 10% a year. So a galaxy 10 million lightyears away this year will be 11m ly away next year, a difference of 1m light years. But a galaxy 50m ly away will be 55m ly away next year (a difference of 5m), and a galaxy 100m ly away will be 110m ly away (10m).

And a galaxy 10 billion ly away will be 11 billion ly away next year -- it has moved further away than all the other galaxies combined. The expansion is uniform but it applies to the space, not the velocity of the galaxies. The more space between two objects, the greater the expansion.

And this expansion is accelerating, which means the 10% rate in our simplified analogy will climb over time, but it is applied everywhere equally.
 
1 day ago  

pup.socket: zepillin: zepillin: pup.socket: zepillin: there was no beginning there will be no end

If there was no beginning and no end, you would not be here.

Why wouldn't I be

I'm just Stardust in motion

Maybe you are, but without a beginning and an end, you'd still have to wait for an infinity for stardust to appear, and that is waiting forever.


I don't understand why you think a beginning is necessary for Stardust to exist. When have you ever experienced something being created from nothing it doesn't happen on the atomic scale.
 
1 day ago  

Ishkur: And this expansion is accelerating


the expansion will contract, contraction and expansion is the way of things

Harkins belives there have been multiple big bangs

I believe there have been infinitel "big bangs" and I believed that years before he came up with the multiple stuff

mathematicians are slow but he will come around
 
1 day ago  

Ishkur: Spermbot: If the rate of the expansion of space is constant, then why aren't all galaxies moving away from each other at a constant speed? Or is the expansion rate of space increasing?

Couple things:

First: Yes, the expansion of the Universe is accelerating. At some point in the future it will be expanding faster than the speed of light, at which point distant galaxies will blip out of existence, being beyond our ability to observe them.

Secondly: This expansion of space is uniform everywhere, but the reason why it seems distant galaxies are moving away faster is because it's not the galaxies that are moving. It's the space between them that is filling up with more space, like raisins in a loaf of bread. The more space between us and a galaxy, the greater the expansion.

Simple analogy: Say all galaxies are moving away from us at a rate of 10% a year. So a galaxy 10 million lightyears away this year will be 11m ly away next year, a difference of 1m light years. But a galaxy 50m ly away will be 55m ly away next year (a difference of 5m), and a galaxy 100m ly away will be 110m ly away (10m).

And a galaxy 10 billion ly away will be 11 billion ly away next year -- it has moved further away than all the other galaxies combined. The expansion is uniform but it applies to the space, not the velocity of the galaxies. The more space between two objects, the greater the expansion.

And this expansion is accelerating, which means the 10% rate in our simplified analogy will climb over time, but it is applied everywhere equally.


Thanks for elaborating on this. I have a followup question based on your remarks:

"At some point in the future, it will be expanding faster than the speed of light, at which point distant galaxies will blip out of existence,"

Hasn't this happened already?  During the roughly 1M years of homo sapiens sapiens' existence, there must have been some galaxies in the infinite universe whose light just barely reached us to begin with at the dawn of our species and have since moved beyond observability due to the expansion of space during the last million years.  The most distant galaxies (relative to our own) won't actually cease to exist, will they?
 
1 day ago  
Are was just too harsh

that's just the way things are

it just is

I'm sticking with is

always thought are was too harsh

I have issues
 
1 day ago  

zepillin: the expansion will contract,


We have zero evidence that it will do any such thing.

The most likely outcome of the universe is Heat Death.
 
1 day ago  

Spermbot: Hasn't this happened already? During the roughly 1M years of homo sapiens sapiens' existence, there must have been some galaxies in the infinite universe whose light just barely reached us to begin with at the dawn of our species and have since moved beyond observability due to the expansion of space during the last million years. The most distant galaxies (relative to our own) won't actually cease to exist, will they?


There is indeed speculation that it may have, however we have no way of actually knowing.

Pop quiz: What is the diameter of the Universe? You might think its 13.72 billion lightyears wide since that is its age, but its actual diameter is closer to (last time I checked) 96 billion lightyears. Why the discrepancy? Because of the expansion of spacetime.

So if we look at a distant object 13.7 billion lightyears away (ie: very close to the Big Bang... I mean that in terms of age, not location), what we are seeing is how it looked 13.7 billion years ago, but since that time it has moved 96 billion lightyears away from us.

It should always be emphasized that these are the limits of the OBSERVABLE universe to us. The universe may be far older and far larger, but we have no means of ever knowing that for certain.

But that's okay. The true answers may never be knowable. Just because we can't count to infinity is no reason to stop counting.
 
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