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Do you believe dark matter is real?

Yes
9 (56.3%)
No
7 (43.8%)

Total Members Voted: 16

Author Topic: Do you believe dark matter is real?  (Read 13674 times)

Offline acecharly

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Do you believe dark matter is real?
« on: 08/04/2012 21:33:38 »
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Offline Phractality

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Re: Do you believe dark matter is real?
« Reply #1 on: 08/04/2012 21:42:26 »
I believe there is matter out there which can only be detected by its gravity. However, I think we're assuming that we understand gravity to a much greater extent than we do. We assume that Newton's law of universal gravitation is absolutely perfect all the way to infinity, but we can't verify that much beyond the limits of our solar system. Extrapolating to the size of our galaxy we conclude that most of the gravity comes from dark matter. I think we could be off by at least an order of magnitude. I don't dispute the conclusions; I just don't have any confidence in them.
 

Offline JP

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Re: Do you believe dark matter is real?
« Reply #2 on: 09/04/2012 02:58:59 »
We know certain forms of "dark" (i.e. doesn't interact gravitationally) matter exist already.  Neutrinos are an example: http://en.wikipedia.org/wiki/Hot_dark_matter
 

Offline syhprum

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Re: Do you believe dark matter is real?
« Reply #3 on: 09/04/2012 06:04:48 »
The article quoted states that Neutrinos interact via gravity
 
 

Offline Gordian Knot

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Re: Do you believe dark matter is real?
« Reply #4 on: 10/04/2012 02:09:55 »
This is one of those subjects where, as a layman, I am finding it difficult to accept what science is claiming.

Statement: The universe appears to be expanding at an ever faster accelerated rate.
Statement: This is not the results science had predicted.
Statement: Something must be causing the universe to expand faster and faster.
Statement: There is nothing we can identify that is causing this faster expansion rate.
Conclusion: It must be something we humans cannot detect. We will call it Dark Energy.

Query. Why do we suspect this Dark Energy exists?
Statement: Because without it, the universe would not be expanding at an ever accelerating rate.

Now I squeaked by logic in college by the skin of my teeth, and with the kindness of a decent teacher. So I am sure my logic flow is full of holes. But actually there are not. There appear to be holes, but in truth, they just cannot be detected. We call this Dark Logic.

Okay the last paragraph was my attempt at a joke. :) But I'm serious about the rest. And that appears to be circular logic to me. Thus my difficulty with this theory.
 

Offline CliffordK

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Re: Do you believe dark matter is real?
« Reply #5 on: 10/04/2012 05:48:19 »
I haven't found the original source calculations for the existence of dark matter.  I have to believe that there are some puzzles with the movement of stars that would benefit from adding more mass to the equations as is done with the dark matter calculations.

I suppose I have troubles with an explanation that there is a hitherto undiscovered particle that accounts for several times the mass of the normal atoms in galaxies including the Milky Way.

if it is out there, my guess is that it would be quite ordinary matter.  What is the mass of cosmic rays?  What about comets and asteroids that are tricky to spot away from the sun?  Is everything we see as CMBR particle in nature?
 

Offline Nizzle

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Re: Do you believe dark matter is real?
« Reply #6 on: 10/04/2012 08:02:12 »
I voted yes, simply because Black Dwarfs, even though they're hypothetical at the moment, seem legit.
 

Offline MikeS

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Re: Do you believe dark matter is real?
« Reply #7 on: 10/04/2012 08:40:41 »
No.  I see no real evidence.
 

Offline CliffordK

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Re: Do you believe dark matter is real?
« Reply #8 on: 30/04/2012 05:27:17 »
I've started working on a model for the Vector Sum of Gravitational Interactions as Solution to the Galaxy Rotation Curve Problem here:
http://www.thenakedscientists.com/forum/index.php?topic=43936.0

It is simply the vector addition of Newton's law of Gravity by calculating the force of gravity between pairs of bodies.

c9652ae3267144f5a37ebbb820063857.gif

being extended into vector notation:

0ce7c51ed30fbb2730c623cbb99d9b2b.gif

See a more complete description including variable definitions under the New Theories topic.

So far it seems to account quite well for the increasing velocity in outermost stars observed in many galaxies, or otherwise decreased orbital velocities of innermost stars, as well as constant orbital periods for large groups of stars in the galaxy which would promote the formation of spirals, bars, and wheels.

No dark energy or dark matter is necessary to make the model work.

The only problem is that my orbital velocities seem to be even greater than some people seem to theorize, but I believe these will be recalculated in the near future to better match the physical possibilities and physical reality.

Anyway, my prediction is that dark matter and dark energy grants and funding will dry up in the next couple of years, and the concepts will only be remembered as science gone awry, inventing new constructs for a problem that didn't truly exist.
 

Offline Guthers

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Re: Do you believe dark matter is real?
« Reply #9 on: 30/04/2012 13:10:37 »
This is one of those subjects where, as a layman, I am finding it difficult to accept what science is claiming.

Statement: The universe appears to be expanding at an ever faster accelerated rate.
Statement: This is not the results science had predicted.
Statement: Something must be causing the universe to expand faster and faster.
Statement: There is nothing we can identify that is causing this faster expansion rate.
Conclusion: It must be something we humans cannot detect. We will call it Dark Energy.

Query. Why do we suspect this Dark Energy exists?
Statement: Because without it, the universe would not be expanding at an ever accelerating rate.

Now I squeaked by logic in college by the skin of my teeth, and with the kindness of a decent teacher. So I am sure my logic flow is full of holes. But actually there are not. There appear to be holes, but in truth, they just cannot be detected. We call this Dark Logic.

Okay the last paragraph was my attempt at a joke. :) But I'm serious about the rest. And that appears to be circular logic to me. Thus my difficulty with this theory.
I feel somebody has to try to address this, and even though I'm no logician I'll try.

First of all, that is your interpretation of what you think scientists and cosmologists are saying, and might not represent their own actual reasoning.

The classical circular argument goes:
"We believe god exists".
"Why do you believe that?".
"It is inconceivable for so many people to believe god exists if he doesn't, therefore he must".
(This was actually the basis of a BBC Radio 4 Lent Talk by John Lennox: http://www.rzim.eu/john-lennoxs-lent-talk-for-radio-4 [nofollow], and he's a maths professor at Oxford. I kid you not. And the BBC is allowed to broadcast this tripe completely uncontested, sheesh  :( )

In other words a widely held belief in the existence of something is used as the only evidence for its own existence. The only other source might be the bible, upon which the belief is based in the first place, and so is neither independent of the argument, nor verifiable or authoritative.

So, unless you consider the observations leading to the inference in your first statement to be no more reliable than say, the bible stories, there already exists evidence in the form of observations which have been independently confirmed, that 'something' (dark energy) exists.

Now, your final 'Query-Statement', purporting to show a circular argument, breaks down, because there is authoritative evidence for dark energy (or at least its effects), whatever it turns out to be, and not just the mere statement of its existence.

Your 'Conclusion' also implies a further step in reasoning, when all scientists have in fact done is given the "something" a name, "dark energy", without actually speculating or stating exactly what it might be. Scientists don't just expect you to believe anything, they are actively out there trying to find out exactly what it is.
« Last Edit: 30/04/2012 13:38:16 by Guthers »
 

Offline Pmb

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Re: Do you believe dark matter is real?
« Reply #10 on: 30/04/2012 13:41:45 »
I believe that Dark Matter exits. Dark matter is estimated to constitute 83% of the matter in the universe and 23% of the mass-energy. It would be arrogant of us to assume that something has to be observable for us (as in "seeing" matter through visible photons) to believe that it exists but in fact the evidence comes from gravitational interaction with galactic matter.
No.  I see no real evidence.
What do you mean by "see" no real evidence? In what sense do you "see" real evidence for other matter such as electrons, protons and neutrons?
« Last Edit: 30/04/2012 13:47:56 by Pmb »
 

Offline Pmb

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Re: Do you believe dark matter is real?
« Reply #11 on: 30/04/2012 13:54:39 »
This is one of those subjects where, as a layman, I am finding it difficult to accept what science is claiming.

Statement: The universe appears to be expanding at an ever faster accelerated rate.
Statement: This is not the results science had predicted.
Statement: Something must be causing the universe to expand faster and faster.
Statement: There is nothing we can identify that is causing this faster expansion rate.
Conclusion: It must be something we humans cannot detect. We will call it Dark Energy.

Query. Why do we suspect this Dark Energy exists?
Statement: Because without it, the universe would not be expanding at an ever accelerating rate.

Now I squeaked by logic in college by the skin of my teeth, and with the kindness of a decent teacher. So I am sure my logic flow is full of holes. But actually there are not. There appear to be holes, but in truth, they just cannot be detected. We call this Dark Logic.

Okay the last paragraph was my attempt at a joke. :) But I'm serious about the rest. And that appears to be circular logic to me. Thus my difficulty with this theory.
Have you compared the logic you use to rationalize other things in physics of which you have a solid belief in? If you don't mind, what are those though processes.

If you have an interest in a solid text on the Philosophy of Science then check this text out at -- http://www.amazon.com/Scientific-Inquiry-Readings-Philosophy-Science/dp/0195119762/ref=sr_1_1?s=books&ie=UTF8&qid=1324671794&sr=1-1

If you're up for an excellent solid text on logical reasoning then I recognize the book at -- http://www.amazon.com/Practical-Logic-Antidote-Uncritical-Thinking/dp/0155030361/ref=sr_1_4?ie=UTF8&qid=1324334182&sr=8-4


I'm curious, you addressed your thoughts on the existance of Dark Energy but you didn't mention your mention of Dark Matter at all. Do you mind if I ask you why that is?

Pete
« Last Edit: 30/04/2012 13:59:30 by Pmb »
 

Offline Gordian Knot

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Re: Do you believe dark matter is real?
« Reply #12 on: 30/04/2012 15:40:45 »
Thank you all for your responses. Starting from the bottom up.

I didn't discuss Dark Matter because, as I understand it, it is not the predominant force at work in the Universe. Dark Energy supposedly makes up some 70+ % of the Universe; Dark Matter roughly 20+ % and the observable Universe the left over. Hence my comments focused on Dark Energy.

Before I go any further into your other questions, I have one about the above underlined statement.

I have heard numerous statements from cosmologists who say Dark Matter makes up 70+ % of the Universe. So I am very confused about the foundation of the theory right from the beginning. So actually I have two questions.

1. Is 70+ % of the Universe Dark Matter or is it Dark Energy.

2. Why do scientists, who tend to be fairly specific in their statements, seem to use the two terms Dark Matter and Dark Energy, interchangeably when referring to that 70%.

(In all instances I am referring to our current time frame. Billions of years ago Dark Matter supposedly made up a much higher percentage of the whole. I'm not talking about that. I am talking about the current state of the Universe.)

 

Offline imatfaal

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Re: Do you believe dark matter is real?
« Reply #13 on: 30/04/2012 16:54:58 »
Gordian - the wikipedia pages are fairly accurate but need reading carefully. 

Dark matter is about 83pct of the MATTER in the universe.  Dark energy is about 72pct of the total MASS/ENERGY of the universe.  Your top unlined phrase is how I understand it.

No scientist would use the terms interchangeable - they are completely different concepts; really only linked by their names. 
 

Offline Pmb

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Re: Do you believe dark matter is real?
« Reply #14 on: 30/04/2012 18:25:08 »
Thank you all for your responses. Starting from the bottom up.

I didn't discuss Dark Matter because, as I understand it, it is not the predominant force at work in the Universe.

My personal opinion - Please don't take this personally, okay? :)

Even so it is Dark Matter which is the topic in this thread, not the most predominant force. If you thought it was more important then you should have added what you did as a side line and not the topic of the post/thread.
 

Offline MikeS

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Re: Do you believe dark matter is real?
« Reply #15 on: 01/05/2012 07:35:23 »
Dark energy is a term that was coined to account for the observed accelerated expansion of space.

There have been various suggestions of what dark energy is.

1) It's a property of space.

2) It originates from the quantum theory of matter.

3) It is a new kind of dynamical energy fluid or field, something that fills all of space but something whose effect on the expansion of the Universe is the opposite of that of matter and normal energy.

4) A last possibility is that Einstein's theory of gravity is not correct.

From
http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/


To my mind the most obvious thing is being overlooked.  The answer is embedded in the first sentence.
"Dark energy is a term that was coined to account for the observed accelerated expansion of space".
"accelerated expansion of space."  a = vf-vi/t.  It is assumed that the acceleration is in the SPACE dimension of space-time.  It could just as easily be in the TIME dimension of space-time.  If time is contracting it would look exactly the same as space expanding, both create a red-shift. 

For those of you who do not think acceleration in the TIME dimension of space-time is possible, I would just remind you that's exactly what gravity is.  The Universe can accelerate in time without getting any larger just the same as the Earth accelerates in time without getting any larger.

I hope the moderators will bare with me for expressing this view in a mainstream thread but my proposal is no more unlikely than the suggestions above and unlike the suggestions above it does not require anything new and it leaves GR intact.
« Last Edit: 01/05/2012 08:13:44 by MikeS »
 

Offline MikeS

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Re: Do you believe dark matter is real?
« Reply #16 on: 01/05/2012 08:12:53 »
Dark Matter

" It was first postulated by Jan Oort in 1932 to account for the orbital velocities of stars in the Milky Way and Fritz Zwicky in 1933 to account for evidence of "missing mass" in the orbital velocities of galaxies in clusters."
http://en.wikipedia.org/wiki/Dark_matter

Galaxies are large, very large.  Light leaving them is emitted from many different time frames simultaneously. There must be a gravitational gradient from center to periphery.  This gravitational gradient must be accompanied by a time dilation gradient.  Time passes faster at the periphery in comparison to the center.  The periphery is rotating slower than it appears as time there is contracted.  The relative velocity at the periphery is slower than it appears.  This would reduce the centripetal force and the tendency of a spiral galaxy to 'wind up'.

My point being, if you do not take relative time dilation into account when talking about velocity you end up with the wrong answer.

Again I ask the moderators to have patience with me for expressing this view in a mainstream thread  but essentially by discussing dark energy and dark mater we are discussing things that are little understood even by the mainstream and as yet, there are no definitive answers.
« Last Edit: 01/05/2012 08:22:53 by MikeS »
 

Offline MikeS

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Re: Do you believe dark matter is real?
« Reply #17 on: 01/05/2012 08:43:10 »
I believe that Dark Matter exits. Dark matter is estimated to constitute 83% of the matter in the universe and 23% of the mass-energy. It would be arrogant of us to assume that something has to be observable for us (as in "seeing" matter through visible photons) to believe that it exists but in fact the evidence comes from gravitational interaction with galactic matter.
No.  I see no real evidence.
What do you mean by "see" no real evidence? In what sense do you "see" real evidence for other matter such as electrons, protons and neutrons?

I was using 'see' as meaning 'aware of'.
I am aware of no real evidence for the existence of dark matter as explained in my last post above.
 

Offline Ophiolite

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Re: Do you believe dark matter is real?
« Reply #18 on: 01/05/2012 08:55:22 »
I chose not to participate in the poll, since the options (Yes, or No) are unscientific. The only proper answer at this time is to say that there are unexplained observations which dark matter currently offers the best explanation for, but which is not inherently convincing.
 

Offline Don_1

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Re: Do you believe dark matter is real?
« Reply #19 on: 01/05/2012 09:10:42 »
A hypothesis is suggested. Attempts are then made to substantiate that hypothesis.

Be it black holes, dark matter or the unicorn, there must come a time when the lack of hard evidence should result in the conclusion 'in all probability, it does not exist'. This should not necessarily be taken as sign to stop looking, but should lead to the exploration of alternative possibilities.

In the case of the unicorn, no evidence of its existence has been found, so we can safely say, in all probability it does not and did not exist. But who knows? Perhaps one day .............

Right now there is no hard evidence of the existence of dark matter, but it is early days and we should not assume anything just yet.

But, science must be careful. We do not want to create another 'God'. Believed by some, not by others and no proof one way or the other.

For now I must vote no, but give me some tangible evidence and I may change my view.
 

Offline Pmb

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Re: Do you believe dark matter is real?
« Reply #20 on: 01/05/2012 10:17:47 »
I was using 'see' as meaning 'aware of'.
I am aware of no real evidence for the existence of dark matter as explained in my last post above.
Have you read an astronomy text where they discuss dark matter and the resaon they postulate it's existance? It's interesting stuff to read.
 

Offline MikeS

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Re: Do you believe dark matter is real?
« Reply #21 on: 01/05/2012 11:32:26 »
Pete,
Iv'e read some and I'm not convinced over the arguments for dark matter.  Obviously some matter will be dark as it does not emit light but is still ordinary matter.

As I mentioned above I think we are just misinterpreting the evidence.
« Last Edit: 01/05/2012 11:35:43 by MikeS »
 

Offline Pmb

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Re: Do you believe dark matter is real?
« Reply #22 on: 01/05/2012 12:29:07 »
Pete,
Iv'e read some and I'm not convinced over the arguments for dark matter.  Obviously some matter will be dark as it does not emit light but is still ordinary matter.

As I mentioned above I think we are just misinterpreting the evidence.
Ahh! I see now. So what you really mean here is not that you see no real evidence but that that evidence you do see doesn't convince you. It seems to me that being misled by the evidence is something different altogether though. What makes you think that we are misinterpretating the evidence?

Pete

ps - I'm beginning to get the impression that its more important, not simply to be convinced by something but to be well versed in the reasoning of what led you to form an opinion of what we read.
« Last Edit: 01/05/2012 12:37:55 by Pmb »
 

Offline MikeS

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Re: Do you believe dark matter is real?
« Reply #23 on: 01/05/2012 13:25:05 »

Pete,
Iv'e read some and I'm not convinced over the arguments for dark matter.  Obviously some matter will be dark as it does not emit light but is still ordinary matter.

As I mentioned above I think we are just misinterpreting the evidence.
Ahh! I see now. So what you really mean here is not that you see no real evidence but that that evidence you do see doesn't convince you. It seems to me that being misled by the evidence is something different altogether though. What makes you think that we are misinterpretating the evidence?

Pete

ps - I'm beginning to get the impression that its more important, not simply to be convinced by something but to be well versed in the reasoning of what led you to form an opinion of what we read.

By real, I meant real to me (convinced me).

I explained it in post #16 of this thread.
What I didn't add was time dilation across the radius of the galaxy seems to me to be by far the simplest explanation and requires nothing new to be added.


Isn't it what we read or learn that convinces us of the validity of an argument?  Personally I have to know what led up to something being accepted as true.  If I don't understand or don't accept something as true then I am likely to question it.

 

Offline Pmb

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Re: Do you believe dark matter is real?
« Reply #24 on: 01/05/2012 14:19:45 »
Quote from: MikeS
Isn't it what we read or learn that convinces us of the validity of an argument?  Personally I have to know what led up to something being accepted as true.  If I don't understand or don't accept something as true then I am likely to question it.
Mike - I'm getting ready to gothe the doctors office. I'll be back in about five hours. Do you have a desire to get into thinings like philosophy? Logic? Epistemology? etc.?
« Last Edit: 01/05/2012 14:36:42 by Pmb »
 

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Re: Do you believe dark matter is real?
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