Post by: acecharly on 08/04/2012 21:33:38
Post by: Phractality on 08/04/2012 21:42:26
Post by: JP on 09/04/2012 02:58:59
Post by: syhprum on 09/04/2012 06:04:48
Post by: Gordian Knot on 10/04/2012 02:09:55
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.
Post by: CliffordK on 10/04/2012 05:48:19
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?
Post by: Nizzle on 10/04/2012 08:02:12
Post by: MikeS on 10/04/2012 08:40:41
Post by: CliffordK on 30/04/2012 05:27:17
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.
being extended into vector notation:
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.
Post by: Guthers 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.I feel somebody has to try to address this, and even though I'm no logician I'll try.
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.
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, 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.
Post by: Pmb on 30/04/2012 13:41:45
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?
Post by: Pmb 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.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.
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.
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
Post by: Gordian Knot on 30/04/2012 15:40:45
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.)
Post by: imatfaal on 30/04/2012 16:54:58
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.
Post by: Pmb 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.
Post by: MikeS on 01/05/2012 07:35:23
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.
Post by: MikeS on 01/05/2012 08:12:53
" 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.
Post by: MikeS 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.
Post by: Ophiolite on 01/05/2012 08:55:22
Post by: Don_1 on 01/05/2012 09:10:42
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.
Post by: Pmb on 01/05/2012 10:17:47
I was using 'see' as meaning 'aware of'.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.
I am aware of no real evidence for the existence of dark matter as explained in my last post above.
Post by: MikeS on 01/05/2012 11:32:26
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.
Post by: Pmb on 01/05/2012 12:29:07
Pete,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?
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.
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.
Post by: MikeS on 01/05/2012 13:25:05
Pete,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?
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.
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.
Post by: Pmb 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.?
Post by: Gordian Knot on 01/05/2012 16:05:10
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.
No offense taken. In my opinion my comments are related to this discussion, although, admittedly indirectly. The question is "Do you believe Dark Matter is real?" That is, Does one believe that something that cannot in any way be perceived is real?" The question pertains to Dark Energy as well in the sense that it is also something we cannot in any way perceive, but is postulated to exist to explain certain dynamics of how the Universe works.
Post by: Gordian Knot on 01/05/2012 16:58:48
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.
Imat, you have explained a critical part of the definition I was misunderstanding. I.E. the "Matter" versus the "Mass/Energy". Looking back at the discussions, the scientists obviously are talking about one or the other of these two concepts, and not using them interchangeably.
Post by: Pmb on 02/05/2012 02:07:14
Quote from: Gordian Knot
That is, Does one believe that something that cannot in any way be perceived is real?"But Dark Matter is percieved. It interacts gravitationaly with all matter which has passive gravitational mass.
Post by: yor_on on 02/05/2012 11:22:56
Have a look at this. New Study Finds No Evidence for Dark Matter in the Milky Way. Posted: 04/21/12. (http://www.astrobio.net/pressrelease/4705/new-study-finds-no-evidence-for-dark-matter-in-the-milky-way)
Post by: yor_on on 02/05/2012 11:28:03
Post by: MikeS on 02/05/2012 11:49:05
Quote from: Gordian KnotThat is, Does one believe that something that cannot in any way be perceived is real?"But Dark Matter is percieved. It interacts gravitationaly with all matter which has passive gravitational mass.
If it exists it may act gravitationally with all matter that has passive gravitational mass. It may not exist. It was formulated to explain an anomaly. It is not the only explanation and it is certainly not the simplest.
Post by: MikeS on 02/05/2012 12:22:42
The link you gave gives practically no information but it does provide another link.
http://www.space.com/11129-dark-energy-theory-universe-expansion.html
"In a new study, a team of researchers led by Adam Riess of the Space Telescope Science Institute in Baltimore, report that they've calculated how fast the universe is expanding to a greater degree of accuracy than ever before, shrinking the error bars on their measurements by about 30 percent."
I believe that is
30% of what? It is assumed it is a 30% improvement in in the measurement that the universe is 'expanding' in the SPACE dimension of space-time. There is absolutely no evidence that the expansion is in the SPACE dimension of space-time. What looks like an expansion in the SPACE dimension of space-time is just as likely to be a contraction in the TIME dimension of space-time. They both look identical. It's a 30% improvement in measurement but but you have to specify what the measurement refers to and in this case it is assumed that it refers to the SPACE in space-time. This is open to question as it could equally refer to the TIME in space-time. Time contraction is by far the simplest explanation as it requires nothing new. See reply #15 in this thread.
For all we know, the Universe could be contracting. If time is contracting fast enough then what looks like expansion could be contraction. As far as I am aware the only evidence for space expanding is in one way or another dependent upon the red-shift. As the red-shift has another and simpler explanation it is just insufficient evidence.
Post by: Pmb on 02/05/2012 13:34:43
That's quite true. Have you studied this anomaly you mentioned here? How do you know that it s not the only explanation?Quote from: Gordian KnotThat is, Does one believe that something that cannot in any way be perceived is real?"But Dark Matter is percieved. It interacts gravitationaly with all matter which has passive gravitational mass.
If it exists it may act gravitationally with all matter that has passive gravitational mass. It may not exist. It was formulated to explain an anomaly. It is not the only explanation and it is certainly not the simplest.
What you said is one reason why postulates can never be proven to be true. There are always other ways to explain observations. Scientists keep running tests to show that all other explainations fail to be true. When that happens a postulate becomes more believable. Consider for example, the following article
Quote
Anti-photon, W.E. Lamb, Appl. Phys, B 60, 77-84For those of you who don't recognize the author, he won the Nobel Prize in physics in quantum electrodynamics!
Abstract. It should be apparent from the title of this article that the author does not like the use of the term "photon", which dates from 1926. In his view, there is no such thing as a photon. Only a comedy of errors and historical accidents led to its popularity among physicists and optical scientists. I admit that the word is short and convenient. Its use is also habit forming. Similarly, one might find it convenient to speak of the "aether" or "vacuum" to stand for empty space, even if no such thing existed. There are very good substitutes for "photon", (e.g. "radiation" or "light") and for "photonics" (e.g. "optics" or "quantum optics"). Similar objections are possible to use of the word "phonon", which dates from 1932. Objects like electrons, neutrinos of finite rest mass, or helium atoms can, under suitable conditions, be considered to be particles, since their theories then have a viable non-relativistic and non-quantum limits. This paper outlines the main features of the quantum theory of radiation and indicates how they can be used to treat problems in quantum optics.
No theory can ever be proven right and therefore what we believe to be true might actually be proven false. And for that reason there will always been room to say "Yeah but maybe someday a scientist might come up with an explanation which is consistent will all know observations but be conceivable with theory so and so so when we run a text to see if it's right we can have reason to doubt the theory.
As far as Dark Matter goes one has to have a good understanding the reasons for it and reasons why other reasons against it we have to keep an open mind.
Consider again the question asked: Do you believe dark matter is real?
Take notice that the question did not ask whether they knew that dark matter was real. To date it is an hypothesis, one that has not yet been substantiated.
Post by: yor_on on 02/05/2012 15:38:41
There is a lot of accelerating expansion going on out there as it seems.
Post by: yor_on on 02/05/2012 16:24:49
Post by: Pmb on 02/05/2012 16:27:07
I think dark energy is here to stay, at least for a while.I think that there is one scenario that has been hypothesized by physicists (E.g. touched on in Gravition and Spacetime 2nd Ed., Ohanian& Ruffini) but has not yet been touched on in this thread. Now my question is Are you certain that you don't believe in the existance of dark matter but that you're taking it out of context?
Consider one of the possible explanations that has been consistent for Dark Matter is black holes. Ask your self whether you believe in the existance in black holes and if so would you consider their existance to be a candidate for dark matter?
Now that you've considered this as a plausible explanation would you now consider the existance of Dark Matter to strong?
Post by: yor_on on 02/05/2012 21:29:29
When it comes to dark matter I don't know, something is needed but what it should be?
I'll wait a while with assuming anything I think. But I liked the idea with neutrinos myself, then again, they are supposed to travel freely in the galaxy and if the research mentioned didn't find any evidence?
"“The amount of mass that we derive matches very well with what we see -- stars, dust and gas -- in the region around the Sun,” says team leader Christian Moni Bidin (Departamento de Astronomia, Universidad de Concepcion, Chile). “But this leaves no room for the extra material -- dark matter -- that we were expecting. Our calculations show that it should have shown up very clearly in our measurements. But it was just not there!” "
So I can't really say what it should be. You have those mini black holes too? Maybe those could be it? I don't really know.
http://www.astro.ucla.edu/~wright/neutrinos.html
Post by: Pmb on 03/05/2012 01:46:20
Hmm, is the question directed to me Pete? Or to Mike? Both maybe :)Both.
Post by: Gordian Knot on 03/05/2012 02:36:33
Quote from: Gordian KnotThat is, Does one believe that something that cannot in any way be perceived is real?"But Dark Matter is percieved. It interacts gravitationaly with all matter which has passive gravitational mass.
Clarification, please. Wouldn't the correct statement be that we perceive the results of dark matter at work? It was not my understanding that we can perceive Dark Matter itself.
Post by: MikeS on 03/05/2012 06:41:38
I think dark energy is here to stay, at least for a while. You could assume that if we all (mass) were shrinking at the same rate that space accelerate/expands, then that might be an sufficient explanation for what we see. As for assuming different 'time rates' as 'a contraction in the TIME dimension of space-time.' I will presume that this is a expansion' of your own ideas, and to be perfectly honest I'm not even sure how to interpret it?We understand from relativity that time is relative. That is not open to debate. We know that acceleration (which is gravity) affects the time dilation factor. That's not open to debate. If we believe in GR then we believe in space-time. Space-time has two components. Space and time. Acceleration has two components, the change in velocity over time. If either of the components changes then it represents acceleration. So acceleration can be a change in distance covered in space per unit time. It can equally be a change in time. The faster you travel in space, the less you travel in time. The faster you travel in time, the less you travel in space.
There is a lot of accelerating expansion going on out there as it seems.
When time contracts each successive second is shorter than the proceeding one. Less photons arrive per second than in a previous second. Less wavelengths of light arrive per second than in a previous second. Less photons arriving per second can have two explanations. (1) Time is contracting. (2) Space is expanding. Less wavelengths of light arriving per second can have two explanations. (1) Time is contracting. (2) Space is expanding.
I am at a loss to understand what is open to debate about the above but I am more than happy to debate it.
I would just add 'time contraction' and 'space expansion' look EXACTLY the same. That may be open to debate but to the best of my knowledge is correct.
Post by: MikeS on 03/05/2012 07:02:37
This one might be more useful to you Mike? it lists the ways ways astronomers, and others, use for deducing/finding a 'dark energy'. New evidence backs dark energy. (http://www.abc.net.au/science/articles/2012/04/16/3476013.htm)
New approach
Professor Charlie Lineweaver, a cosmologist from the Australian National University, says this study demonstrates a new way to confirm the accelerated expansion of the universe.
"There are five ways to determine how fast the universe's expansion rate is accelerating," says Lineweaver.
"Schmidt used supernovae, which is still the most accurate method. There's also baryonic acoustic oscillations which are density waves that propagate through the universe, there's the cosmic microwave background radiation and you can also count the numbers of star clusters at given distances."
"Having the same conclusions reached by different methods is a tremendously important tool in any scientific research."
"All science is built on that. You can imagine if one method gave you one answer and another method gave you a different answer, so what you're looking for is consistency."
http://www.abc.net.au/science/articles/2012/04/16/3476013.htm
All that seems to confirm is the measured accuracy of the red-shift.
My concern is that all of the above evidence relies upon the red-shift. The red-shift is the very thing that is open to debate. It's a circular argument. The red shift can have two explanations, time contraction or space expansion. As they look the same both would account for the above five points.
Post by: MikeS on 03/05/2012 07:28:11
I think dark energy is here to stay, at least for a while.I think that there is one scenario that has been hypothesized by physicists (E.g. touched on in Gravition and Spacetime 2nd Ed., Ohanian& Ruffini) but has not yet been touched on in this thread. Now my question is Are you certain that you don't believe in the existance of dark matter but that you're taking it out of context?
Consider one of the possible explanations that has been consistent for Dark Matter is black holes. Ask your self whether you believe in the existance in black holes and if so would you consider their existance to be a candidate for dark matter?
Now that you've considered this as a plausible explanation would you now consider the existance of Dark Matter to strong?
I guess black holes could be considered by definition to be dark matter as we can't see them.
However, that is not necessarily true. If matter continues to accelerate once inside the EH then it is going backward in time. If it is going backward in time then charge and parity have reversed, can it still be considered to be 'matter' or is it now 'antimatter'? In which case a black hole is not dark matter but dark antimatter. Something that is time reversed can not emit light. Reflected light is reflected into the past. Either way it cannot be seen, just like a black hole.
When I think of dark matter I think of what is required to account for the existence of galaxies in the way they are generally perceived. Black holes would do the job but it would require an awful lot of them and they would probably announce their existence in ways that we do no observe.
Rather than answer the question directly I would suggest it was the wrong question. Perhaps the question should have been. Why do we have to postulate the existence of dark matter as a means of answering a question in the presence of a simpler answer to that question? See explanation in reply 16 of this thread.
Post by: Pmb on 03/05/2012 12:32:09
I guess black holes could be considered by definition to be dark matter as we can't see them.As I already mentoned, science doesn't operate on notions like "necessarily true."
However, that is not necessarily true.
Post by: MikeS on 03/05/2012 16:46:39
Unfortunately for the likes of me I have no peers to form a consensus.
Post by: JP on 03/05/2012 18:18:11
Post by: Pmb on 03/05/2012 19:12:55
Science operates on a consensus of opinion amongst your peers. It owes little to what is actually true but as we seldom know what is true it is probably the best that we can expect.All that is quite untrue. The reason science operates on a consensus of opinion amongst its peers is only because one has to learn so much on the topic of discussion that by the time they learn enough to do so they have become peers. It's similar to people who speak French. They only speak French with French speaking people because it's only French speaking people who can undersand them.
Unfortunately for the likes of me I have no peers to form a consensus.
As far as It owes little to what is actually true... is also wrong but you'll never know that unless you become versed in the language of science. I myself spent years upon years spending most of my days learning physics, the philosophy of physics and language of physics (i.e. math) to become able to understand what I needed to know and that was only the basics to learn what I wanted to learn. For examle, it took me many years to understand tensor analysis just so that I could learn general relativity.
You could always learn to become a physicist by starting off with the basics (basic physics and math) and that will give you the basics to put yourself in the position to start to lean physics (since physics forum is where you keep posting from what I see). Warning: It's a very long road but it's worth the travel.
Post by: MikeS on 04/05/2012 07:09:57
I was not criticizing science in using the peer review system. I think my view of the peer review system is pretty neutral. I said " it is probably the best that we can expect."
Science operates on a consensus of opinion amongst your peers. It owes little to what is actually true but as we seldom know what is true it is probably the best that we can expect.
Unfortunately for the likes of me I have no peers to form a consensus.
You could always learn to become a physicist by starting off with the basics (basic physics and math) and that will give you the basics to put yourself in the position to start to lean physics (since physics forum is where you keep posting from what I see). Warning: It's a very long road but it's worth the travel.
You presume I have no formal training in physics or math. I would not be so presumptuous. If you wish to debate my ideas, even with a view to proving me wrong, I would be delighted but please do not adopt a condescending attitude toward me.
Post by: imatfaal on 04/05/2012 09:54:39
Mike and Pete - no more comments about the person, education, or perceived attitude please; we are dangerously close to the borders of acceptability so let's get back to substantive science before anyone goes too far.
Post by: Pmb on 04/05/2012 10:08:49
Post by: Pmb on 04/05/2012 10:23:50
MODENOTE....
After I take a vacation will follow your directions when I come back.
Post by: yor_on on 04/05/2012 13:48:43
Mass, and 'energy'?
And what is 'energy'? The closest analogue we can experience would be 'photons/waves' as I see it. Do you believe it possible that light 'propagates' in space? Without heating it, assuming a arrow, since the BB? Well, if you see a reason for it not getting 'warmer' there, and you think its propagates. Then do you believe in constraining it to a 'system', to give that radiation a 'mass' in modern formulation, a particles invariant 'rest mass'?
And if you do that, what are your ideas of conservation laws? And what are your ideas of the whole SpaceTime as a 'system'?
And no, this is not directed to anyone :)
Just me wondering.
Post by: yor_on on 04/05/2012 13:58:07
=
Maybe that is the reason for a expansion? Keeping a SpaceTime in equilibrium.
Which would make the reason some sort of symmetry. Not necessarily the one I suggested here though.
One need to remember that when radiation interact with matter, it also reflects from it, as well as refracts etc etc. And matter presents 'heat', amongst other phenomena, from such interactions.
Post by: yor_on on 04/05/2012 14:19:44
That final 'space' whatever it will be, can then be assumed to have a gravitational potential, and so a metric called 'gravity', giving it its 3-D shape not needing any 'matter', or, be assumed to not have any 'metric' at all, as it will have no 'gravity', meaning that this 'propagating energy' now 'propagates' in, what?
Nuthin?
Post by: MikeS on 05/05/2012 07:58:18
Making an assumption about a persons training can't logically be considered condescending and making an assumption about such training says nothing about an assumption about their intelligence. In any case I think it'd be best for mt not to prticipate in discussions with people who are so offended.
Pete,
That's a cop-out. I would far rather we debate. I am pretty sure you do not agree with much that I believe to be true but I would far rather you (or anyone) prove my ideas wrong than not debate them.
Post by: Pmb on 05/05/2012 16:40:40
That's a cop-out.Please refrain from using a derogatory statements, e.g.
Definition of cop-out
1. A failure to fulfill a commitment or responsibility or to face a difficulty squarely.
2. A person who fails to fulfill a commitment or responsibility.
3. An excuse for inaction or evasion.
If you can resist the temptation to refrain frowhat I consider a derogatory statement then I'd be glad to continue this discussion with you, but only when we stay within the bounds of epistmology.
I would far rather we debate. I am pretty sure you do not agree with much that I believe to be true but I would far rather you (or anyone) prove my ideas wrong than not debate them.As I said several times, theories cannot be proven "true." In fat no theory has ever been proven true. Why don't you pick up a book like The Logic of Scientific Discovery by Karl Popper or The Strcture of Scientific Revolution - 3rd Ed. by Thomas Kuhn and I'd be more than happy to discuss those as they pertain to Dark Matter?
Otherwise please explain what it means to you to prove a theory true of false. E.g. explain how Newton's Laws were proven true.
Post by: Pmb on 05/05/2012 16:42:17
Thinking about mini black holes. what is gravity coupled too?What do you mean coupled too? I've never seen that term used in a scientific use.
Mass, and 'energy'?
And what is 'energy'? The closest analogue we can experience would be 'photons/waves' as I see it. Do you believe it possible that light 'propagates' in space? Without heating it, assuming a arrow, since theRegarding "what is energy" see - http://home.comcast.net/~peter.m.brown/mech/what_is_energy.htm
The closest analogue we can experience would be 'photons/waves' as I see it.The first exampl;es that a physics student comes across is mechanical energy
Do you believe it possible that light 'propagates' in space?Yes.
And if you do that, what are your ideas of conservation laws? And what are your ideas of the whole SpaceTime as a 'system'?A conservation law is a law of physics which states that a physical quantity remains constant in time.
Post by: JP on 05/05/2012 18:47:24
MODENOTE
Mike and Pete - no more comments about the person, education, or perceived attitude please; we are dangerously close to the borders of acceptability so let's get back to substantive science before anyone goes too far.
I'm locking this thread since it continued to go off track despite the above warning.