Are dark matter and dark energy just buzzwords for we don't know?

Bullet cluster could only be explained by the hypothesis of dank matter by the incompetent theoretical physicists, and thats pretty much the only meme they have when it comes to the subject of dank matter.

Learn what evidence means.

Do you know what the Bullet Cluster is? In short, we can map out the location of the matter by gravitational lensing. We can then count the stars, and count the dust, and such.
arstechnica.com/science/2015/03/colliding-galaxy-clusters-offer-stongest-case-yet-for-dark-matter/

The gravity is not coming from between the galaxies where we expect the stardust to be. It's coming from the galaxies themselves, showing little to no trace of collision, in spite of the fact that we can see that the matter has been displaced by the collision.

You have to be pretty crazy to suggest a modified theory of gravity where gravity comes from where the matter would be if it didn't collide.

Currently, the only sane option available is there is some additional matter that does not collide with itself (or only does so weakly), aka dark matter.

PS: Not just the bullet cluster. We have other galaxy collisions. There's also other lines of evidence, such as from the cosmic microwave background radiation.

> the only sane option available
Is this what you resort from "There's pretty solid evidence" ?

Dark matter:

Total mass of our universe = 27%

Observable mass = 4%

4 + x = 27

x = 23

x = dark matter

Dark, as in doesn’t interact with light.

Matter, as in comprised of matter.

Dark energy:

The curvature of the universe has been measured to be flat, as confirmed by the cosmic microwave background.

The total gravitational energy of our universe has been measured to be 0.27.

This would indicate open curvature, as a flat universe would be omega = 1.

Therefore, there must be something else contributing to the total gravitational energy of our universe.

Empty space is actually a bubbling – boiling – brew of virtual particles and fields popping in and out of existence.

Empty space has energy.

As we know the curvature of the universe is flat, that the gravitational energy measured against its mass is 0.27 and that empty space has energy, therefore the missing 0.73 must be coming from the energy of empty space.

Et = 0 / omega = 1

0.27 + x = 1

x = 0.73

x = dark energy

Dark as in, unobservable directly

Energy, as in it is fucking energy.

Are you honestly saying that the entire thing is based on our inability to observe that mass with our puny technological capabilities ?

>Are you honestly saying that the entire thing is based on our inability to observe that mass with our puny technological capabilities?

No, you have completely misunderstood.

It is based on the indirect observation of mass that doesn't interact with light.

Dark energy has also been indirectly observed.

These are experimentally verified phenomena.

I'm not quite sure why they are so misunderstood, however perhaps it's the spooky names.

> It is based on the indirect observation of mass that doesn't interact with light.
I'm very sceptical about the accuracy of this measurement and the tons of things they could have missed when doing it.
> Dark energy has also been indirectly observed.
how so ?

>I'm very sceptical about the accuracy of this measurement and the tons of things they could have missed when doing it.

How did they measure it, user?

And what could they have missed?

>how so ?

Why don't you tell me, user.

You seem to have a good understanding of cosmology.

Well if you didn't understand shit you could have just said so. you didn't have to recite the shit you don't understand as if you knew them very well and could verify their legitimacy.

I can explain if you would like, it's just that you seem to be doubting the legitimacy of something that you clearly don't understand.

Reply with:

>I don't know shit

And then I shall tell you everything I know about dark matter and dark energy.

I don't know shit.
Now explain me the process of detecting mass (accurately) from thousands of lightyears away, explain me how dark energy is proven and observed.

They are the "answers" to the issues that arise from our predictive models of the universe. They have a good base but its more of a "ok shit doesnt work the way its supposed to so yeah"

Ok, I'm going to post an explanation from the cosmology thread I made the other day, which was sadly lost to 404.

k

You all make me wish I had the math background to test my personal crackpot hypothesis that our universe is the interior of a black hole and that the expansion of our universe is thanks to mass being added, which causes the event horizon to expand, uniformally expanding our universe.
Though the fact that the mass of a black whole is contained at its event horizon indicates if my crackpot idea is correct then you lose a spacial dimension every step you take down.

As a quick reminder and introduction, let’s take a look at gravitational energy and the Earth:

If a coin is flung up into the air, how do we determine whether it will escape the atmosphere or return to Earth?

Et = ½ mv^2 - GMm/r

Total gravitational energy is equal to kinetic energy minus potential energy; positive energy minus negative energy.

Et >0 = escape

Et 1 = collapse

B/A

Now, let’s determine the gravitational energy of a galaxy of mass m at the edge of a region with radius R:

Et = ½ mv^2 - GMm/r

We can multiply both sides by a positive number without changing anything and divide by m, as m is also a positive number, so we’ll multiply by 2:

2/m Et = v^2 - 2GM/r

As the velocity of a galaxy at a given distance is proportional to the distance, and the constant of proportionality is H, then v^2 is equal to H^2 R^2.

Now, what is the total mass of a sphere with radius R?

Well the volume of a sphere with radius R is 4/3 π r^3 and as the mass of a sphere with radius R is equal to volume times the average density, then we can write the equation as:

2/m Et = H^2 R^2 - 2G [(4π/3) ρR^3] /R

In order to further simplify, as R2 is a positive quantity we can divide by it, which leaves us with:

2/mR^2 Et = H^2 - 8 πG/3 ρ

Now, let’s refer to the constants 2, m and Et as minus kappa, so that 2/m Et is represented by –k:

-k/R^2 = H^2 - 8 πG/3 ρ

This is Einstein’s equation for an expanding universe, derived with all the factors of π and 3, which will ultimately determine the evolution of the universe.

Minus kappa is a constant related to the total energy of the galaxy, which in general relativity is the curvature of the universe.

The nature of the expansion of the universe is dependent on its curvature.

Therefore, if the total energy of the galaxy in question is positive then kappa is negative, which indicates that it will continue expanding infinitely.

If the total energy is negative then kappa is positive, which indicates that it will collapse.

However, if the final value is zero then it will continue expanding, slowing down but never quite stopping, so that at ∞ v = 0.

The same is true of the universe as a whole.

Now, in order to determine the total energy of the universe we must determine the density of the universe and measure it against the critical density.

If the density of the universe is equal to the critical density then the universe is flat.

If it is greater than the critical density then the universe is closed.

If it is less than the critical density then the universe is open.

The critical density of the universe will be defined by ρc.

ρ > ρc = closed universe
ρ < ρc = open universe
ρ = ρc = flat universe

ρ/ ρc = Ω

Ω = >1 = closed universe
Ω = 1 = collapse

Ω =

How do we determine the density of our universe?

Well, Kepler showed that the square of the velocity of planets from the sun is inversely proportional to the distance from the sun:

v^2 = 1/R

Newton showed that the force of gravity is equal to the gravitational constant times the masses of the objects in question divided by the distance between their two centres:

F = GM1M2/r^2

Cavendish showed that it was possible to calculate G, which modern physicists have calculated to be:

6.67428 × 10^−11N-m^2/kg^2

The existence of a universal force of gravity allows us to state that:

v^2 = GM/r

Since we have a value for the strength of gravity, then the velocity of the moon around the earth can be measured and compared to its distance from the earth, subsequently allowing us to calculate the mass of the earth, which is:

5.972 × 10^24 kg

The same can be done for the sun, however only to an accuracy of 1 part in 1000, due to the difficulty in measuring such a small effect size as gravity.

In fact, gravity is tremendously weak.

If you were to fall from the top of a building, you wouldn’t even make a dent in pavement below and this is due to the fact that gravity is so much weaker than electromagnetism.

Gravity may have accelerated you 50m towards the earth, however the electromagnetic forces resulting from electrons in your body interacting with electrons in the concrete would stop you in a fraction of an inch.

Most materials do not stop you in your tracks because they are solid, as in reality they are mostly empty space: it’s the electromagnetic interaction that brings you to a halt.

In fact, electromagnetism is almost 40 orders of magnitude stronger than gravity..

The suns mass has been calculated to be approximately:

1.989 × 10^30 kg

We can measure the mass of a galaxy similarly.

Our solar system is moving around the edge of our galaxy at a rate of one orbit per 200 million years and we can use this information to measure the mass of our galaxy.

The velocity of the sun around the galaxy is 220km/sec and its distance is 8kpc light years, therefore the initial calculation of the mass comes out as:

10^11 solar masses

This is equivalent to 100 billion stars, which is great as it corresponds to our observations.

However, we want to do better than that so we take a look at objects that are further out.

Now, as we know we are at the edge of our galaxy and velocity should fall off at the square root of the distance from the centre.

After looking at satellite galaxies, molecular clouds and globular clusters that are up to ten times the distance from the centre of the galaxy as we are, we find that the velocity doesn’t fall off, but instead remains constant.

What does this mean?

After all:

V^2 = GM/r

If GM/r is constant and r is ten times bigger, then M must be ten times bigger, which means that there is ten times more mass enclosing our galaxy than expected.

The same is true of other galaxies.

The rotation curve does not fall off in relation to the location of the stars, but instead remains constant..

>Pic related

Therefore, either gravity breaks down although we have no reason to believe it does on the scale of galaxies, or there is ten times more mass enclosing galaxies than we would expect..

This is what we refer to as dark matter.

In fact, there is so much dark matter in the universe (10x all the protons and neutrons in the universe) that it may turn out to be a new type of elementary particle, which means that it is likely to be everywhere, including here on earth.

This means that we can build experiments to try and detect it, although it interacts so weakly that it passes right through the earth, therefore the equipment used will have to be extremely sensitive.

Now, these rotation curves, do they continue to remain flat forever?

We are only able to measure rotation curves up to a certain distance, due to our limited powers of observation, therefore this calculation cannot tell us how much mass is in the universe, it can only tell us the lower limit on that value.

If we want to know the value of Ω then we have to measure mass on larger scales, which we can achieve using gravity or more specifically: gravitational lensing.

We know that gravity curves space-time and subsequently light, therefore it is theoretically possibly for gravity to bend light in such a way that it acts as a lens, thereby magnifying and potentially duplicating an image.

In this respect, an image of a galaxy cluster 5 billion light years away may include multiple images of a galaxy 10 billion light years away, due to gravitational lensing induced by the mass of the cluster.

>pic related; the blue ghostly images are images of a galaxy 5 billion light years behind the galaxy cluster, resulting from gravitational lensing

We can use general relativity to discover how much mass is in this system and where it is distributed, in order to produce such an image..

This is achieved by undertaking a mathematical inversion process, which then allows us to produce an image of the mass of the system:

>pic related

The resulting image indicates that there is forty times more mass in the system than would be expected.

We can then use this data and extrapolate to estimate the mass of the universe, due to the uniformity of the universe.

An initial calculation produces a result of:

Ω = 0.30 ± 0.1 (95%)

This value being less than 1 indicates that we are living in an open universe.

However, this estimate is only based on the mass around clusters of galaxies.

How do we measure the total mass of the universe?

We do so by measuring the geometry of the universe, which involves finding a triangle..

On a flat plane the sum of the angles of a triangle is 180 degrees, however on surface with positive curvature the sum is greater than 180 degrees, just as one with negative curvature produces a triangle with a sum of less than 180 degrees.

>pic related

If we can find a big enough triangle, then we can measure the curvature of the universe.

The largest image we have of our universe comes in the form of the cosmic microwave background, which is essentially a baby picture of our universe at the tender age of 380,000 years old..

>pic related

This is an image of the cosmic microwave background.

It is incredibly uniform, however not completely as it features hot and cold spots.

The hot spots are approximately 1/1000th of a degree hotter than the average and the cold spots are 1/1000th of a degree colder.

This slight variation is what allowed for the creation of matter; these are the primordial lumps, created at the beginning of time, which went on to become galaxies, stars, planets and ultimately us.

This diagram features the surface of the cosmic microwave background at a distance of one degree in angular size, which corresponds to around 380,000 light years in size:

>pic related

The fact that the CMB is so uniform is very puzzling..
An angular distance of one degree is roughly equal to a lump that is 380,000 lightyears across, which means that, as the universe itself was only 380,000 years old, light from one particular lump would not have had enough time to reach another and, subsequently, information would not have been able to be communicated between distant regions of the universe.

Therefore, there is no reason to expect the CMB to be so uniform.

This implies that some form of order preceded creation of the CMB.

In relation to our search for a method for measuring the curvature of the universe, we only need to take a look at the size of the primordial lumps present in the CMB.

This is because the largest lumps that could possibly form would have been 380,000 light years across, as, due to the age of the universe, if they were any larger gravity would not have been able to act on them and therefore they would not have been able to collapse.

Now, the apparent angular distance of a lump 380,000 light years across (1 degree), is dependent on the curvature of the universe.

In an open universe, light rays would bend outward as time reverses, therefore the lumps would appear smaller than it actually is, such as 0.5 degrees.

Likewise, in a closed universe light rays would bend inwards as time reverses, therefore the lumps would look larger, say 2 degrees.

However, in a flat universe light rays travel in a straight line and therefore the lumps would appear to be approximately 1 degree.

Therefore, all one has to do is simulate universes featuring lumps of 0.5, 1 and 2 degrees respectively, and then compare them with the image of the CMB.

This is exactly what physicists have done and the results are extraordinary.

>pic related

This image of the CMB compared with simulated universes featuring lumps of varying sizes, allows us to conclude that we live in a flat universe; the lumps appear to be 1 degree in angular distance.

However, all the mass in the universe amounts to 0.3 as shown earlier, therefore both the visible matter and dark matter combined only amount to 30% of the mass required for a flat universe.

Therefore, we have to ask: where’s the other 70% coming from?

The odd thing is that it seems to be situated in empty space.

That is to say, there’s energy where there is nothing; most of the energy in the universe resides where there is nothing.

If you take a region of space and remove all the particles, the radiation and just everything, then it will still weigh something.

It turns out that when you combine quantum mechanics and relativity, empty space is a boiling – bubbling – brew of virtual particles and fields popping in and out of existence on a time scale far too small for us to observe them, and this is happening everywhere.

For example, less than 5% of the mass of a proton can be accounted for by its 3 quarks.

However, although we may not be able to observe them directly, we can measure their effects indirectly.

This is known as dark energy.

The fact that we can calculate that most of the mass of a proton comes from virtual particles and fields, means that we can do the same calculation to determine how much energy virtual particles and fields can give to the energy of the universe.

However, upon doing so we find that the energy of empty space is approximately 120 orders of magnitude bigger than everything we observe.

This is the worst prediction in all of physics.

So, physicists wracked their brains and came up with the idea that perhaps there exists some form of underlying symmetry that had yet to be discovered, that would allow for a cancellation of energies.

Well, oddly it turns out that if you put energy into empty space gravity is actually repulsive:

>pic related

Therefore, if the universe was really dominated by the energy of empty space then it would be speeding up, not slowing down as predicted.

Then in 1998, more extensive data concerning the expansion rate of the universe came to show that the expansion of the universe is actually speeding up.

This is shown by the fact that the supernovae towards the end of the plot do not follow the predicted path along the curve, but instead place much higher:

>pic related

It was then calculated exactly how much energy would have to be added to empty space to facilitate this accelerated expansion, which turned out to be exactly the value that was puzzling us.

That is to say, if we put around 70% of the energy of a flat universe into empty space then everything works.

If we add in dark energy then the value is no longer 0.30 ± 0.1, but rather Ω = 1.02 ± 0.02.

More recent figures suggest that 73% of the universe resides in nothing, 23% in dark matter and only 4% in luminous matter, of which we make up less than 1%.

We live in a universe in which we are tantamount to a smidge of cosmic pollution; we are wonderfully insignificant.

So the previously chaotic energy calculation has been remedied and we know we live in a flat universe, however since Ω = 1 the total energy of the universe must be 0:

0 = H^2 - 8 πG/3 ρc

This means that you can get 100 billion galaxies with 100 billion stars out of precisely nothing, that is to say once you allow for gravity: as gravitational potential energy at infinity is 0 and positive work has to be carried out by an external force in order to increase the distance from a point in infinity to a massive body, then masses must have a potential energy value less than zero, therefore gravitational potential energy is negative.

Has it been ruled out that a large portion of the universe hasn't already been converted to something we can't yet detect by intelligent life?

I could carry on and talk about inflation, however I'll stop there for now.

Anyway, here is a simulation of the QCD vacuum based on experimental data, which shows that empty space is not empty at all:

science.energy.gov/~/media/np/images/actionanimation.gif

This is a gluon field, which is essentially what you would see if you stared at empty space and could see gluons.

The red hot spots indicate where the gluon field is strong.

Isolated lumps correspond with the knotted-winding nature of the gluon field.

It hasn't been ruled out, however it also hasn't been considered as there would be no way to detect it.

David Icke, the mental face, has some odd conspiracy theories relating to this, involving Saturn.

Anomalous magnetic moment of the electron, probably.

Dark is code word for mystical, exciting, the unknown. Same strategy to make religion exciting back in the era of centralized organized religion.

You can both use the concept both to excite and to scare. Very powerful social tool.

non-luminous matter is only one hypothesis among many. Alternatives include gravity that doesn't strictly obey the inverse square law (inverse square is an approximation).

pretty much a placeholder model in order for the math to work out, yes

Yes.
However using complex mathematical predictive functions we can estimate what it looks like and is made of.
However Dark matter has been created before and observed.

lol moron

Not an argument.

why do people do this?

OK, Mr. Tyson. Meanwhile actual scientists stick to actual real science

Again, not an argument.

No it isnt, my dear autistic friend. Not everything is a formal debate. I am mocking you

>Veeky Forums
>real scientists

Irrelevant to the validity of my statements.

>validity of my statements
This is comedy gold you retarded faggot

Not one refutation made.

pls read
again
We are not having a debate my autistic friend. It is funny that you think idiots deseve to be refuted.
lol moron
Come back when you have learned that your opinion doesnt matter that much in the scientific community

Opinion is always irrelevant.

Statements irrelevant to the topic at hand.

Use of ad hominem indicates inability to refute statements.

>ad hominem
You dont even know what you are talking about.
insult =/= ad hominem
lol. why is it that everybody that throws around these logical fallacy terms, doesnt even understand them?

I also laugh so hard at your inability to understand, that I am not even trying to refute your opinion that is obviously based on some pop-sci yt video.
You should read this, my main man:
en.wikipedia.org/wiki/Dunning–Kruger_effect

Inability to differentiate between ‘ad hominem’ and ‘ad hominem argument’ indicates ignorance of contemporary usage of Latin phraseology.

Dunning-Kruger effect well understood.

No refutations made.

In addition, the above statements are not based on opinion.

They are a description of the data combined with theoretical and hypothetical interpretation.

That is all.

en.wikipedia.org/wiki/Ad_hominem

You are so dumb it hurts.

>Dunning-Kruger effect well understood
Yeah and heavily effected by it.

>No refutations made
Please keep saying this over and over again. Why do autistic people like repeating things so much?

>not based on opinion
Oh shit. If you say so. I am having a real good laugh here. You might be trolling, but I dont even care, this is gold

Mate, to be honest I'm not even that user.

I'm off work with a broken leg and bored as fuck.

I reckon the info in those posts are from a Lawrence Krauss lecture series, that feature him promoting the zero energy universe hypothesis as if it were experimentally verified.

What are you up to?

Wanna be bum buddies?

You cheeky bastard... kek

Poes law is in full effect here. Oh boy

...

Very informative, thank you sir. Are there books that cut to the essence like this? I find that all physics books that I tried are very tedious about (seemingly) trivial things.

I'd say lectures are your best bet:

youtube.com/watch?v=gA1s15sCi34

youtube.com/watch?v=wMI-ot-n-aw

youtube.com/watch?v=uhwuU9l10PM

youtube.com/watch?v=68azBRH_DUc

google.com/search?q=is our universe inside a black hole