# The Percentage of dark matter

I have a theory about what dark matter and dark energy is and so far my theory can explain the % of dark matter, atoms and dark energy for the present universe and the 380 000 old universe base on the Wilkinson Microwave Anisotropy Probe findings
http://map.gsfc.nasa.gov/news/5yr_release.html
but I need to be sure, I need more confirmations that it will work for any age of the universe

If anyone can help me, I am looking for the %s of the dark matter, atoms and “dark energy or/and photons” in a 6x10^9 years old universe‏, my problem is that I am not an astrophysicist; I cannot work the equations. Anyway I need the %s to verify my theory.
I calculated the %s for the 6x10^9 years old universe:
47.838% dark matter, 9.112% atoms, 43%"dark energy or/and photons"

Thanks.

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cepheid
Staff Emeritus
Gold Member
You should know that overly speculative posts and personal theories are both against PF rules and that this thread will probably get locked.

If anyone can help me, I am looking for the %s of the dark matter, atoms and “dark energy or/and photons” in a 6x10^9 years old universe‏, my problem is that I am not an astrophysicist; I cannot work the equations.

Theories in the physical sciences are mathematical models. There is no other way to describe nature unambiguously. If you don't have any equations, then you don't have a theory.

It is not overly speculative post; I just said my calculations (or theory) so far are verified by the findings of the Wilkinson Microwave Anisotropy Prob.
And I have a mathematical model, I posted my findings base on my theory for the %s of the dark matter, atoms and “dark energy or/and photons” in a 6x10^9 years old universe.
‏ 47.838% dark matter, 9.112% atoms, 43%"dark energy or/and photons"

My equations are very simple and are based on my theory of the geometry of time, and so fare they work, I just need to help to verify it, I do not claim anything, I do not claim that I am right but maybe I just found something.

Albert Einstein quote:“Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.”

marcus
Gold Member
Dearly Missed
assuming spatial flatness, matter fraction 0.27, and Hubble rate 71 km/s per Mpc.

Google "cosmo calculator" and verify that redshift z = 0.984 corresponds to the age you mention---6 billion years.

So you are talking about distances being 1/1.984 what they are today. About half.

Taking ordinary matter and dark matter together, the matter density would be about 8 times what it is today.

As long as you are just asking questions about past conditions according to the standard model everything is fine and folks will try to answer. You should probably think about explaining your own theory on some other discussion board though---our focus is on understanding mainstream cosmology.

The estimated Hubble constant with those parameters, at redshift 0.984, would be 119.62 instead of 71 km/s per Mpc. So bigger by what factor?
Bigger by a factor of 119.62/71.

The square of that is 2.84

That means the critical density was 2.84 times what it is now.

But the matter density which is .27 of critical now was 8 times bigger so as a fraction of critical it was .27*8/2.84

I get that the matter fraction was 76% of critical then!

Or putting in 1.984 instead of 2, for a little more precision I get 74%

So according to me at least, your model fails this test. You say the matter fraction at age 6 billion years should be 57%

I say that according to standard cosmology at 6 billion years of age the matter fraction was not 57% but rather it was around 75% (my rough estimates were around 74-76)

I could have made a mistake though! Hopefully someone else will confirm, or else correct me if I made an error.

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Interesting 75% (Dark matter + Atoms) it is the same percentage base on the Wilkinson Microwave Anisotropy Probe findings for a 380 000 years old universe.
http://map.gsfc.nasa.gov/media/080998/index.html

If you are right for the first 6 billion years of the universe, the % stayed the same, 25% dark energy or/and photons and 75% atoms/dark matter until dark energy started to accelerate the expansion of the universe..?
Today %s are 72% dark energy, 4.6 atoms and 23 dark matter.

Interesting 75% (Dark matter + Atoms) it is the same percentage base on the Wilkinson Microwave Anisotropy Probe findings for a 380 000 years old universe.

That chart looks odd to me. I think that someone was vastly oversimplifying things. In particular, the baryon/photon ratio and the baryon/neutrino ratio shouldn't change much after freeze out. So I don't see how they are getting the numbers they got.

Also, you are looking at two data points. There is a ton of other data that comes in from WMAP.

The other problem is that most of the universe today does not consist of "atoms" but rather "ions". The probably mean "baryons".

Also some things that we expect:

1) the ratio between dark matter and ordinary matter should have remained constant for the last several billion years.

2) dark energy is a recent thing. There was no evidence of dark matter at the time of the CMB.

Also if you are proposing that photons and neutrinos turned into dark energy, there are several reasons why that won't work. One is that if photons were interacting to create dark energy, then the early universe would have looked "fuzzy."

It seems that the amount of visible normal matter is changing significantly over time - and becoming non visible normal matter:

http://www.cosmosmagazine.com/news/4653/galaxies-are-running-out-gas [Broken]

I also read recently that many more wandering brown dwarf failed stars than normal stars are now believed to exist - hopefully not in our backyard!

I dont know if any of this causes a change in the ratios discussed above.

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Theories in the physical sciences are mathematical models. There is no other way to describe nature unambiguously. If you don't have any equations, then you don't have a theory.

Cepheid, Is this really strictly correct, if you have no equation, you have no theory?

Well fortunately I recently discovered a Math program which can create equations for almost any plot of interdependant values there is.
I am not sure it adds to the Physical understanding of what is responsible though, it just helps me calculate a value from the other values.

Also some things that we expect:

1) the ratio between dark matter and ordinary matter should have remained constant for the last several billion years.

2) dark energy is a recent thing. There was no evidence of dark matter at the time of the CMB.

Also if you are proposing that photons and neutrinos turned into dark energy, there are several reasons why that won't work. One is that if photons were interacting to create dark energy, then the early universe would have looked "fuzzy."

1) If the ratio between dark matter and ordinary matter have remained constant for the last several billion years, it is a problem for my theory, in my model the % of dark energy has been growing faster than the % of dark matter.

2) I do not think dark energy is a recent thing, if it is; it means that Dark energy appeared from nowhere and it is not believable to me.

I am not proposing that photons and neutrinos turned into dark energy, in the 380000 year old universe you cannot see/observe dark energy because the size of the universe at the time and the amount of photons and neutrinos, in another words dark energy was hiding “behind” the % of photon and neutrinos.
I believe dark matter was present from the beginning of the universe as dark energy, you cannot see/observe it in the 380000 year old universe because the size of the universe at the time and the difference with dark energy is that dark matter was “hiding behind” the % of mass or atoms.

(The term dark in dark matter and dark energy comes from the realization that in the today universe we are missing 96% of it and we cannot explain it. The 96% missing universe was always there, we cannot see it in the early universe and in the today universe.
We call it “dark” because again we do not know what it is, if “dark” did not exist at the beginning it does not exist today, “nothing can appear from nothing”)

It seems that the amount of visible normal matter is changing significantly over time - and becoming non visible normal matter:

http://www.cosmosmagazine.com/news/4653/galaxies-are-running-out-gas [Broken]

I also read recently that many more wandering brown dwarf failed stars than normal stars are now believed to exist - hopefully not in our backyard!

I dont know if any of this causes a change in the ratios discussed above.

I am sure that we cannot see/observe all the "visible" matter in the universe but if the not seen "visible" matter is only 1% of the total of matter in the universe it doesn’t really “matter”.

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phinds
Gold Member
2021 Award
2) dark energy is a recent thing. There was no evidence of dark matter at the time of the CMB.

Are you sure about that? If it didn't exist, how did it arise spontaneously? Now we have the UNIVERSE arising spontaneously (by some theories) AND we have dark energy arising spontaneously.

I thought it was simply the case that the EFFECT of dark energy only started overcoming gravity about 7 billion years ago, not that dark energy came into existence at that time.

BillSaltLake
Gold Member
For a fairly accurate ΛCDM formula for the expansion factor, a = 0.713[sinh(1.28t/t0)]2/3, where t0 is the present age. This assumes that ΩΛ now is 0.73, so that matter (including DM) is now 0.27 of the total. (from 1 Gyr and later, photon+ neutrino energy density was I think <1% and the formula ignores this contribution). This also normalizes to a = 1 at the present.
In the time range you're talking about, the matter density was proportional to 1/a3, while the "DE" density was constant and photon+ neutrino energy density was negligible (but prop to 1/a4).
Although this formula arises from the ΛCDM model, it's very accurate at matching supernova data, etc., so whatever the actual formula ends up being, it's very close to the above.

cepheid
Staff Emeritus
Gold Member
Cepheid, Is this really strictly correct, if you have no equation, you have no theory?

I was trying to make the point that in physics, a "theory" that amounts to little more than a vague verbal description of natural phenomena that doesn't have any quantitative, testable predictions is not useful or even meaningful. Furthermore, any new theory should be able to explain what existing theories are able to explain, at least as well as they do, if not better. Yes, I stand by the statement that physical theories are mathematical models that describe nature. No other form of description is precise enough, and I would argue that any other form of description lends itself to too much ambiguity.

Well fortunately I recently discovered a Math program which can create equations for almost any plot of interdependant values there is.
I am not sure it adds to the Physical understanding of what is responsible though, it just helps me calculate a value from the other values.

It's really not clear what your point is here. Maybe I am misinterpreting you, but your point seems to be, "just because you have mathematical equations doesn't mean that you have a theory." Well: I never said that it did. If A = "mathematical model" and B = "physical theory", then what I asserted was that:

(not A) ==> (not B).

As you should know, it does NOT automatically follow that the inverse, A ==> B, is true, nor was it my intention to assert that.

cepheid
Staff Emeritus
Gold Member
Are you sure about that? If it didn't exist, how did it arise spontaneously? Now we have the UNIVERSE arising spontaneously (by some theories) AND we have dark energy arising spontaneously.

I thought it was simply the case that the EFFECT of dark energy only started overcoming gravity about 7 billion years ago, not that dark energy came into existence at that time.

Yeah you're right. The dark energy density is constant with time (maybe), whereas the matter density varies inversely with the cube of the scale factor (in other words, as the universe expands, matter gets diluted). Therefore, for much of the past, the matter density has been higher than the DE density, but steadily decreasing. It is only when these two density curves cross that the universe switches from being "matter-dominated" to "dark energy-dominated" (in terms of what dominates the dynamics of the expansion). This is a transition that, according to the standard model, has just occurred more or less "now."

1) It seems that the amount of visible normal matter is changing significantly over time - and becoming non visible normal matter:

2) I also read recently that many more wandering brown dwarf failed stars than normal stars are now believed to exist - hopefully not in our backyard!

I dont know if any of this causes a change in the ratios discussed above.

It doesn't. The ratios involve the total amount of "normal matter" that is inferred from things like big bang nucleosynthesis and galaxy distribution. When cosmologists talk about "dark matter" they are talking about "weird dark matter." It turns out that there is a huge amount of "normal dark matter" that cosmologists don't worry about but which other astrophysicists do.

You don't have a theory. You have a curve fit. That's not a theory.

If you take some points and draw a line through those points that's not a theory. If you have an explanation that will let you draw a line through the points *without looking at the points* that's a theory.

1) If the ratio between dark matter and ordinary matter have remained constant for the last several billion years, it is a problem for my theory, in my model the % of dark energy has been growing faster than the % of dark matter.

The ratio of dark matter and ordinary matter has to be constant or else you'd see dark matter turning into ordinary matter and vice versa. We don't.

2) I do not think dark energy is a recent thing, if it is; it means that Dark energy appeared from nowhere and it is not believable to me.

You are not the only one that is bothered by this, but if you look through the telescope, this is what you see. The fact that what you see isn't what you expected is why the people that first saw it, got Nobel prizes.

There's the "principle of least weirdness" you go with the explanation that is "least weird." Right now "dark energy" is the "least weird" explanation for what people are seeing.

in another words dark energy was hiding “behind” the % of photon and neutrinos.

So why can we see it now? One thing seems to be true about the universe is that the average conditions are the roughly the same everywhere, so there is no "behind". How does dark energy "hide behind" neutrinos and photons.

Are you sure about that? If it didn't exist, how did it arise spontaneously? Now we have the UNIVERSE arising spontaneously (by some theories) AND we have dark energy arising spontaneously.

That was an ops. I meant "dark energy". "Dark energy" is something recent and you can get perfectly good explanations for CMB without dark energy.

I thought it was simply the case that the EFFECT of dark energy only started overcoming gravity about 7 billion years ago, not that dark energy came into existence at that time.

Maybe. But you don't see dark energy in CMB. It could be there, but you don't see it. Also whether it was there and not seen or whether it was something that came into existence after the early universe is an open question.

Yeah you're right. The dark energy density is constant with time (maybe), whereas the matter density varies inversely with the cube of the scale factor (in other words, as the universe expands, matter gets diluted).

That's assuming that dark energy consists of the cosmological constant. If it consists of something else like quintessence or modified gravity or voids, then it's different.

Now as data is coming in, it's starting to look more and more like cosmological constant.

This is a transition that, according to the standard model, has just occurred more or less "now."

Which really bothers people. One rule of thumb in cosmology is "you are not special, and if it looks like you are, then something is off." The fact that the numbers are send up so that we just happen to be living in the transition is suspicious.

This also normalizes to a = 1 at the present.
In the time range you're talking about, the matter density was proportional to 1/a3, while the "DE" density was constant and photon+ neutrino energy density was negligible (but prop to 1/a4).

That also explains what the chart was measuring. You'd expect that the ratio between photons, neutrinos, and baryons to be roughly constant, but as the universe gets hotter, photons and neutrinos end up with more energy and more pressure.

Now if you measure mass (i.e. gravitational attraction) then things are different. Neutrinos and photons have zero rest mass, so you don't have them overwhelm baryons until things get a lot hotter.

Also, to the OP. This is a theory. We have three components.

Dark matter + baryons = energy proportional to 1/a^-3
Photons/Neutrinos = energy proportional to 1/a^-4
Dark energy = energy constant

The first two we can observe from experiment. The last thing we are guessing. If dark energy has constant energy, then we should see a particular expansion rate (which is what we are starting to see). If it turns that we don't see something with constant energy, then we look at what we do see and then figure out what the energy dependence is.

That's a theory......

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cepheid
Staff Emeritus
Gold Member
That's assuming that dark energy consists of the cosmological constant. If it consists of something else like quintessence or modified gravity or voids, then it's different.

Now as data is coming in, it's starting to look more and more like cosmological constant.

That's why I said "maybe" in parentheses :tongue:

Which really bothers people. One rule of thumb in cosmology is "you are not special, and if it looks like you are, then something is off." The fact that the numbers are send up so that we just happen to be living in the transition is suspicious.

It is indeed suspicious...

Hi Dynamotime:

I can’t give you an answer to your question on the ratios of dark matter, atoms, and dark energy when the universe was only about half its current age. I’m a skeptic and it seems like dark matter and dark energy are terms used because without these parameters, models of galaxies tend to fall apart.

I’m interested in your theory of the geometry of time. Can you provide more details?

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You don't have a theory. You have a curve fit. That's not a theory.

If you take some points and draw a line through those points that's not a theory. If you have an explanation that will let you draw a line through the points *without looking at the points* that's a theory.
I have an explaination for it...

The ratio of dark matter and ordinary matter has to be constant or else you'd see dark matter turning into ordinary matter and vice versa. We don't.
I did misread his post, I thought he posted that a constant ratio existed between dark Matter and dark Energy. Did not made a lot sense to me…..That's what happens when you use copy and paste..
Yes I agree with you the ratio of dark matter and ordinary matter has to be constant. And it is.

You are not the only one that is bothered by this, but if you look through the telescope, this is what you see. The fact that what you see isn't what you expected is why the people that first saw it, got Nobel prizes.

There's the "principle of least weirdness" you go with the explanation that is "least weird." Right now "dark energy" is the "least weird" explanation for what people are seeing.

So why can we see it now? One thing seems to be true about the universe is that the average conditions are the roughly the same everywhere, so there is no "behind". How does dark energy "hide behind" neutrinos and photons.
We can “see” it now because the size of the universe, size matters :).
It is like when 2 objects are really close to each other and you cannot see what it is between same but once you move the objects away from each other you realize something is (exist) between same. And that something is dark matter and dark energy, and again if dark energy and dark matter appeared from the nothingness of space it does not make a lot sense to me, you cannot get nothing from nothing…0+0≠1

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marcus
Gold Member
Dearly Missed
...I posted my findings base on my theory for the %s of the dark matter, atoms and “dark energy or/and photons” in a 6x10^9 years old universe.
‏ 47.838% dark matter, 9.112% atoms, 43%"dark energy or/and photons"

My equations are very simple and are based on my theory of the geometry of time, and so fare they work, I just need to help to verify it, ...

But when we checked as you asked us, we falsified your theory. It now seems time to scrap it.

Your prediction was that around age 6 billion years, matter is 57% of critical.

This is wrong, as far as I know. According to the standard model which fits data quite well the matter fraction at that time was around 75% of critical.
=======================================

Anyone can do the calculation. Not to put to fine a point on it, let's say z = 1.
With standard numbers for the present day like .27, .73, and 71 km/s per Mpc we get that the age back then (at z = 1) was 5.93 billion years. That's close enough to 6 billion to show what I mean. Just put those numbers in one of the standard calculators. For instance:

http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html

This also tells you that the Hubble parameter back then was 120.7 km/s per Mpc.

So the ratio is 120.7/71 = 1.7. The square of 1.7 = 2.89.

So we know that critical density back then was 2.89 greater than today.

But with z=1 the matter density obviously has to be 8 times what it is today. So as a percentage of critical, it is .27*8/2.89 = 0.7474... ≈ 75%

That's essentially what I got earlier using exactly 6 billion years. It is close enough so the percentage is going to be nearly the same.

There is a big difference between what a professional cosmologist would say---namely 75%---and what you say your "theory" predicts---namely 57%. This is the kind of test you were asking for in your first post, at the beginning of this thread.

but I need to be sure, I need more confirmations that it will work for any age of the universe

If anyone can help me, I am looking for the %s of the dark matter, atoms and “dark energy or/and photons” in a 6x10^9 years old universe‏, my problem is that I am not an astrophysicist; I cannot work the equations. Anyway I need the %s to verify my theory.
I calculated the %s for the 6x10^9 years old universe:
47.838% dark matter, 9.112% atoms, 43%"dark energy or/and photons"

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Cephid in reply to your post 14, consider a mathematical equation: x = y * z

I use it every hour, but it is completely meaningless and irrelevent to anything until I add the Physics part which relates to current, resistance, and voltage, and then we have Ohms law!

I fully get that Cosmology is now completely dependant on advanced mathematics, most of which is well past me. But I contend that it doesnt stop me understanding the Physical principles and their interdependancies if they are well laid out. Also the reasons and observations help further in understanding.

Charts of the Physical variables are also a good way of communicating the Physics especially for me because I seem to be able to visualise interdependancies quicker in chart form.
As an example I think that some of the most interesting solutions to the Cosmo calculator that Marcus links to could also be useful in Chart form:

http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html

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DaveC426913
Gold Member
I have an explaination for it...
What you have is a hypothesis.

What you have is a hypothesis.

Yes you are right I have a hypothesis, it is not a theory yet, to become a theory I need to verify my numbers and they need to be compatible with the Cosmology Standard Model, so far the only to come up with numbers is Marcus.
I say that according to standard cosmology at 6 billion years of age the matter fraction was not 57% but rather it was around 75% (my rough estimates were around 74-76)

I could have made a mistake though! Hopefully someone else will confirm, or else correct me if I made an error

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Dynamotime I am certainly not saying it applies here but dont forget the old saying "correlation does not prove causation", I suspect that has been the downfall of many a theory!

marcus
Gold Member
Dearly Missed
But when we checked as you asked us, we falsified your theory. It now seems time to scrap it.

Your prediction was that around age 6 billion years, matter is 57% of critical.

This is wrong, as far as I know. According to the standard model which fits data quite well the matter fraction at that time was around 75% of critical.
...

I just did the calculation a second time to be sure. See post #24.
Others here (Dave, Cepheid, Twofish, ...) could certainly repeat the calculation, it is simple arithmetic. But I see no need for that.

Just in case anyone wants to duplicate the work, it's trivial except for the remark that according to standard cosmology the Hubble parameter at z=1 is 120.7 km/s per Mpc.
(that was courtesy of Morgan's calculator).

Critical density goes as the square of the Hubble, and 1.7 squared is 2.89. So at the time of z=1, critical density is 2.89 times present. The percentages always refer to critical. They sum to near one because they are percents of crit.

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cepheid
Staff Emeritus