Extraordinary claims require extraordinary proof

[ben m]

I have no idea if those scientist are correct or not, I am pointing out the obvious evidence that dark matter and dark energy are by no means "proved", or accepted by everyone as proved.

Translation: "I found this paper on Google, but didn't read it. Since I was trying to argue that dark matter is wrong, I posted it figuring it probably supported my argument. I knew I could retreat to a teach-the-controversy stance if I got caught."

You could have just said "please put me on ignore" instead of dancing around the issue.

 

[Reality Check]

I have no idea if those scientist are correct or not, I am pointing out the obvious evidence that dark matter and dark energy are by no means "proved", or accepted by everyone as proved.

There are multpile observations for the existence of dark matter, including the measurement of the actual gravitational lensing by dark matter. This looks like proved to me.

 

[robinson]

Lately, some scientists have turned the question around, from “is dark matter correct?” to “is our standard theory of gravity correct?” Most recently, Fermilab scientists Scott Dodelson and former Brinson Fellow Michele Liguori demonstrated one of the first pieces of theoretical evidence that an alternative theory of gravity can explain the large scale structure of the universe.

http://www.physorg.com/news85310822.html

 

[robinson]

Here I attempt a review of some sanity checks of these fast-developing theories from galaxy rotation curves, gravitational lensing and cosmic acceleration. I will also discuss some theoretical aspects of the vacuum energy, and point out some analogies with electromagnetism and the Casimir effect.

http://arxiv.org/abs/0802.1775

 

[robinson]

There seems to be a plethora of theories and experiments concerning all aspects of these dark matters.

 

[Reality Check]

There seems to be a plethora of theories and experiments concerning all aspects of these dark matters.

That is correct. We know that dark matter exists so we want to find out about it. This is a technique used in many areas of science.
We know what dark matter does and does not (it has mass, it does not radiate, it does not interact strongly with matter) so its properties are well established. The remaining task to to find out what it is. This means creating theories (the more the better) and testing them against experiment.

 

[CFLarsen]

That just isn't true.

I have no idea if those scientist are correct or not

Then why did you post the references and argued that it wasn't true?

 

[robinson]

Oh, and we havent[sic] a clue how else to explain all that data if DM doesn't exist.

He claims "we" haven't a clue, and I pointed out many people are researching and looking at ways to explain the issues that caused DM to be theorized.

I don't know if they are correct, being skeptical of them as well as those proposing a dark matter/energy solution.

 

[Michelle Lyon]

I never took a physics class, but if Dark Matter is made up of energy particles rather than mass, couldn't that energy be recorded somehow? Don't they call it Dark because there's no energy registering (at least not with current technology)?

 

[Dancing David]

Hi Michelle,

It is called dark because it does not interact with electro magnetic forces (in theory) so it does not radiate in any spectrum of photons, usually that is how astronomer see things.

It is inferred from the rotation of stars in the outer parts of galaxies (hotly contested by the plasma crowd) and also through things like gravitational lensing in certain situations.

In some ways it could be very like neutrinos, which don't generaly interact very often with baryonic matter.

 

[ynot]

Actually lets make this more explicit for you:
Look around you. How many dimensions do you think that you exist in?
If it is 1 then don't try standing up.
If it is 2 then welcome to Flatland.
I hope that you come up with 3 because that is how many I deduce.
Congratulations, you have just constructed an abstract model of the universe! And using abstract math!

But you have just spent time deducing that there exists a 3D universe. So the actual universe includes time. If you want to keep track of change then you need to include time in your model of the universe. You now have an abstract space-time model of the universe using 4 dimensions.
Can you visualize 4 dimensions and see what happens when the space part of the universe expands with time? I cannot.

Scientists have a technique to deal with things that are hard to visualize - they simplify. To simplify a 4D model we just drop 1 dimension. Thus a 3D sphere that expands with time simplifies to a 2D sphere that expands with time. Scientists call that a balloon. You are right that it does not have a volume - the inside of the balloon is the time dimension.

The actual 3D reality of the universe is self-evident and there‘s no abstract math required to deduce that fact. Math didn’t and doesn’t create actual reality.

I’m not happy to call time an actual dimension. Perhaps an abstract dimension? Actual 3D things move relative to other actual 3D things and we call this time. A thing can move in relation to other things but a thing can’t move in relation to itself. How can the relative movement of other things change the actual 3D reality of a thing in to an actual 4D reality?

As I understand it there is no inside to the balloon in the anology, just the outer surface. As far as I’m concerned the only actual reality is a 3D balloon. The rest is make-believe.

Converting reality in to abstract impossiblities only “simplifies” things to the point that they don’t have to make sense.

 

[Reality Check]

The actual 3D reality of the universe is self-evident and there‘s no abstract math required to deduce that fact. Math didn’t and doesn’t create actual reality.

I’m not happy to call time an actual dimension. Perhaps an abstract dimension? Actual 3D things move relative to other actual 3D things and we call this time. A thing can move in relation to other things but a thing can’t move in relation to itself. How can the relative movement of other things change the actual 3D reality of a thing in to an actual 4D reality?

As I understand it there is no inside to the balloon in the anology, just the outer surface. As far as I’m concerned the only actual reality is a 3D balloon. The rest is make-believe.

Converting reality in to abstract impossiblities only “simplifies” things to the point that they don’t have to make sense.

You are right - a 2D balloon has only a surface. If that seems incredible to you then what about the mobius strip - it is a surface with inly 1 side!

Converting reality to abstract math means that we can predict things.

 

[Zeuzzz]

The actual 3D reality of the universe is self-evident and there‘s no abstract math required to deduce that fact. Math didn’t and doesn’t create actual reality.

I’m not happy to call time an actual dimension. Perhaps an abstract dimension? Actual 3D things move relative to other actual 3D things and we call this time. A thing can move in relation to other things but a thing can’t move in relation to itself. How can the relative movement of other things change the actual 3D reality of a thing in to an actual 4D reality?

As I understand it there is no inside to the balloon in the anology, just the outer surface. As far as I’m concerned the only actual reality is a 3D balloon. The rest is make-believe.

Converting reality in to abstract impossiblities only “simplifies” things to the point that they don’t have to make sense.

A very fine point. How can you test that time is an actual dimension? its what most models are based on now, but the actual basis for using time as a dimension is ambiguos at best.

A brief history of modern cosmology:

Cosmologists insist that the weakest force known to science, gravity, controls the universe. Early in the twentieth century, Einstein redefined Newtonian gravity by placing it in a metaphysical framework. He combined the three measurable physical dimensions of space with a mathematical ‘dimension’ that cannot be measured with a ruler: time. The claimed success of Einstein’s ‘thought experiments’ encouraged mathematicians to follow his lead, and they have dominated physics and cosmology ever since. It must be said that Einstein himself showed integrity by doubting his own work. But his followers have shown no such restraint. In their devotion to mathematical abstractions, cosmologists wrote themselves a blank check, with the freedom to invent anything necessary to save the theory when observations didn’t fit.

Around the middle of the twentieth century, astronomers were shocked to discover unimaginable concentrations of energy in deep space. Limited to gravitational models, they could only envision supermassive, super-compact objects below the limit of resolution. The laws of physics were suspended to allow for ‘black holes.’ On discovering galactic motions that directly contradicted gravitational models, physicists imagined vast regions of invisible ‘dark matter.’ Since no one could see it, they were free to place it wherever needed to preserve appearances. Then, when other dubious assumptions led them to think that the universe is expanding ever faster—the ultimate violation of gravitational dogma—‘dark energy’ was invented. It is an exotic energy neither witnessed nor understood, but supposedly dominating cosmic motions. As the ‘queen of the sciences,’ modern cosmology has imposed boundaries on all related disciplines, with disastrous consequences.

 

[Reality Check]

A very fine point. How can you test that time is an actual dimension? its what most models are based on now, but the actual basis for using time as a dimension is ambiguos at best.

A brief history of modern cosmology:

Cosmologists insist that the weakest force known to science, gravity, controls the universe. Early in the twentieth century, Einstein redefined Newtonian gravity by placing it in a metaphysical framework. He combined the three measurable physical dimensions of space with a mathematical ‘dimension’ that cannot be measured with a ruler: time. The claimed success of Einstein’s ‘thought experiments’ encouraged mathematicians to follow his lead, and they have dominated physics and cosmology ever since. It must be said that Einstein himself showed integrity by doubting his own work. But his followers have shown no such restraint. In their devotion to mathematical abstractions, cosmologists wrote themselves a blank check, with the freedom to invent anything necessary to save the theory when observations didn’t fit.

Around the middle of the twentieth century, astronomers were shocked to discover unimaginable concentrations of energy in deep space. Limited to gravitational models, they could only envision supermassive, super-compact objects below the limit of resolution. The laws of physics were suspended to allow for ‘black holes.’ On discovering galactic motions that directly contradicted gravitational models, physicists imagined vast regions of invisible ‘dark matter.’ Since no one could see it, they were free to place it wherever needed to preserve appearances. Then, when other dubious assumptions led them to think that the universe is expanding ever faster—the ultimate violation of gravitational dogma—‘dark energy’ was invented. It is an exotic energy neither witnessed nor understood, but supposedly dominating cosmic motions. As the ‘queen of the sciences,’ modern cosmology has imposed boundaries on all related disciplines, with disastrous consequences.

I have to agree that considering time as a dimension is a mathematical construction not reality. The nice thing is that it works! Spacetime is an invaluable concept in all of physics, especially when there are relativistc velocities involved.

A few points:
A lot of the text above is a direct quote from an "electic universe" web page. They think that if you can belive in an electrically powered sun you will believe in anything and buy their books and DVDs.
"Einstein himself showed integrity by doubting his own work" is an outright lie. The only part of his work that he doubted was the addition of a cosmological constant to General Relativity.

The laws of physics were not "suspended to allow for ‘black holes.’". The first black hole solution was to Newton's law of gravity in 1783 (it assumed that light was particles with mass). This was mostly ignored since light was thought to be a massless wave. Then along came General Relativity. GR also has black hole solutions but the first solutions were not realistic because they had mathematical singularity. In 1958 the first solution without a singularity was derived. In 1963 the work of Roy Kerr derived a solution for a rotating black hole which was acceptable to astronomers (stars rotate and from black holes thus black holes should rotate). There is observational evidence for both stellar black holes and supermassive black holes.

The central part of science is that if you observe something that does not fit a theory then you have to either throw the theory away or modify the theory. Sometimes a theory may be still used subject to limitations, e.g. we still use Newtons law of gravitation for launching and guiding satellites around Earth. When it was found that galaxies were not rotating as predicted and that galaxies in galactic clusters were not orbiting as predicted then scientists could have thrown away General Relativity (or maybe even Newton). However by postulating that something existed that did not radiate (was dark) and had mass, scientists could explain everything. It was a risky move because if dark matter did not exist then many years of research would have been wasted. Of course we now know that dark matter exists: NASA Finds Direct Proof of Dark Matter. We still have a few theories as to what dark matter actually is.

Dark energy is in a similiar state as dark matter used to be - needed to explain the observations but without direct proof.

 

[Zeuzzz]

"Einstein himself showed integrity by doubting his own work" is an outright lie. The only part of his work that he doubted was the addition of a cosmological constant to General Relativity.

"Since the mathematicians have invaded the theory of relativity, I do not understand it myself anymore." - Albert Einsten

The laws of physics were not "suspended to allow for ‘black holes.’". The first black hole solution was to Newton's law of gravity in 1783 (it assumed that light was particles with mass). This was mostly ignored since light was thought to be a massless wave. Then along came General Relativity. GR also has black hole solutions but the first solutions were not realistic because they had mathematical singularity.

Einstein did not like the singularity in the centre of the black hole. In 1935 he and Rosen found another solution to the equations of a black hole.

 

[Reality Check]

"Since the mathematicians have invaded the theory of relativity, I do not understand it myself anymore." - Albert Einsten

Einstein did not like the singularity in the centre of the black hole. In 1935 he and Rosen found another solution to the equations of a black hole.

One quote? Where is the paper or book from Einstein doubting his theories?
No one liked the singularity in the centre of the black hole. Where is Einstein's doubt? Other solutions also removed the singularity.

 

[robinson]

Einstein considered the "Schwarzschild singularity" and black holes as bizzarre constructs, resisting the logic of his own theory right up to his death in 1955.

Einstein absolutely rejected the singularity. He called black holes, "Schwartzschild singularities", and insisted that "Schwartzschild singularities do not exist in physical reality"

Albert Einstein, "On a stationary system with spherical symmetry consisting of many gravitating masses", Annals of Mathematics, Oct. 1939, vol 40, No 4,

Albert Einstein, The Meaning of Relativity, Princeton University Press

Albrecht Folsing, Albert Einstein, a Biography, 1997, Penguin Books

 

[sol invictus]

Einstein didn't like or understand black holes, that's true. He also didn't accept quantum mechanics even though his own work on the photoelectric effect (for which he was awarded the Nobel) pointed directly to it. He spent the later years of his life searching for a unified theory, and failed. He was wrong about many things.

He was also the greatest genius in physics that ever lived. That's life - it's not black and white.

The opinions of any individual are totally irrelevant. What matters is the physics, and we understand the physics far better now than Einstein ever did. That's what 90 years of work on a theory will buy you.

 

[robinson]

The data on magnetism effecting gravity is pretty dang interestin. The Earth's field is very weak. I wonder what we would find on Jupiter, with it's huge magnetic field?

This is is one of those things that nobody thinks to look for, because they assume it can't happen. Most consider EM and gravity to not have any effect on each other at all. Period. So most don't even look at the data.

If magnetism effects gravity, even on a very very small level, it changes things. But it sure would make Einstein happy to know.

 

[MattusMaximus]

I never took a physics class, but if Dark Matter is made up of energy particles rather than mass, couldn't that energy be recorded somehow? Don't they call it Dark because there's no energy registering (at least not with current technology)?

A good question Michelle. Two things to consider:

1. From Einstein's famous equation, E = mc², we know that mass is simply another form of energy. This is why massless particles like photons (i.e., light) are affected by gravity, because they have a mass equivalence.

2. As to your question about the possible direct detection of dark matter particles, this is something which many physicists are hoping the Large Hadron Collider at CERN will be capable of doing. Here's a link on this:

http://en.wikipedia.org/wiki/Dark_matter#Detection_of_Dark_Matter

As someone else on the thread already pointed out, we know this stuff called dark matter is out there. The observations have confirmed the existence of dark matter, but we still don't really know what it is and other details.