Is the Era of Dark Matter Over?

**dalem** · 18 Feb 12,, 08:52

Originally Posted by snapper

I think USSW- hits the problem on the head when he says "we shouldn't be too sure of our definitions". By defining 'Classical science' as requiring 'proof' scientists actualy limited themselves when it comes the probabilities involved in particle physics; in many ways the 'classical proof' simply is NOT possible. Perhaps this is not the fault of the scientists - the requirements are no longer relevant?

Waaay back in my early-sleepy-morning Astronomy 451 class, Professor Cowley, the nicest, most atrociously boring teacher you could ever hope to have, snapped the 8 of us awake and out of our notebooks when he turned from the board after droning on about energy equations and mass derivations and rotational momentum of whatever the topic was that day and said "of course, all of these conclusions assume that the Universal Gravitational Constant is indeed a constant, which we really have no proof of."

Also, a healthy dose of common sense is always good too. Except at the quantum level of course. I personally find it easier to believe that G is in fact, variable over time, for instance, than I do in an [i]accelerated[i/] inflationary universe.

But really, cosmology and quantum mechanics are mind-blowingly weird, so who knows?

-dale

**appu_sen** · 06 Apr 12,, 15:29

As far as I understand, dark matter is just like 'normal' matter but so dense that the gravitational pull is too high (like black holes). No light escapes it and hence no direct method of observation. One has to rely on its effect on its surrouding to measure its properties. Since indirect measurement method is more inaccurate and difficult than direct observation, the measurement technology to measure dark matter will evolve slowly and after many trial and error. Remember: for indirect measurement to be acurate, you have to first prove accuretely that the theory of the indirect behaviour.

**appu_sen** · 06 Apr 12,, 15:42

Originally Posted by Officer of Engineers

Not that I am anywhere near Stephen Hawkings brilliance but when he had to invent imaginary time in order for his equations to work ... and then go on to state that imaginary time might as well be real because it works in his equations to predict things, I just rolled my eyes. Here we have an absolute admission that that he had to invent something out of the blue and then to state that it's real ...

What is the difference between imaginary time and the angels make it so?

You know when I was a kid and learning about complex numbers, I was told that the whole complex algebra revolves around an imaginary number (-1)^0.5 I thought, why to use something which doesn't exist in reality, that too in mathematics

. I thought it was a conspiracy against us kids to burden us more and more

.

But as I evolved, I have a completely different view.
I think it is always the case. You invent some tools (here imaginary time)to meet your need (your equations). Then test is with experiments and then the tool becomes way of life. Then a new requirement comes along which the tool is not able to satisfy and you either upgrade the tool or invent new tool.

Same happened with Fourier series, Fourier transforms, Laplase transforms etc.

**USSWisconsin** · 06 Apr 12,, 17:10

The mathmatical term "imaginary" does not have the same meaning as it does in common speech. We might say all numbers are "imaginary" since we don't see numbers in nature - we use numbers, but that isn't the point. Imaginary time is analogous to imaginary numbers in these calculations - it is adding another dimension to time - like complex numbers make scalars two dimensional. Complex time can be expressed as (t + i*t) like a complex number. Where i is the square root of negative 1. Complex numbers are used and are essential in electro-magnetic field calculations - which we routinely today use to build things like radars and computers. That said, having imaginary time doesn't make the astrophysics theories correct. When we are able to put them to use in intergalactic navigation, and they work - then we might have some justifiable confidence in these theories.

**appu_sen** · 06 Apr 12,, 18:39

Originally Posted by USSWisconsin

The mathmatical term "imaginary" does not have the same meaning as it does in common speech. We might say all numbers are "imaginary" since we don't see numbers in nature - we use numbers, but that isn't the point. Imaginary time is analogous to imaginary numbers in these calculations - it is adding another dimension to time - like complex numbers make scalars two dimensional. Complex time can be expressed as (t + i*t) like a complex number. Where i is the square root of negative 1. Complex numbers are used and are essential in electro-magnetic field calculations - which we routinely today use to build things like radars and computers. That said, having imaginary time doesn't make the astrophysics theories correct. When we are able to put them to use in intergalactic navigation, and they work - then we might have some justifiable confidence in these theories.

That is exactly what my point is. At this point, the scientists may use some tools (like imaginary time) to see if their equations work. When technology evolves to make use of the equations for some real application, we at that time will be saying, what a great idea and what a great man who could think of imaginary time. Then even after some generations (when things like imaginary time will be taught in schools) some people might be debating like we are now, where one of them will be explaining imaginary time like you are explaining imaginary numbers to me now.

We need to give the 'Astrophysicsist' some time (may be a generation or 2) to prove their 'theories'. If they stop thinking now (or we throw them out of job), there will be no equations tomorrow to convert to real applications.

And the mathmatical term "imaginary" does have the same meaning as it does in common speech. There is no number whose square is -1.

**Officer of Engineers** · 06 Apr 12,, 18:48

Or it could fall by the waste side. Newtonian mathematics doesn't work with Einstienian mathematics and it's not use in that area.

**appu_sen** · 06 Apr 12,, 19:56

Originally Posted by Officer of Engineers

Or it could fall by the waste side. Newtonian mathematics doesn't work with Einstienian mathematics and it's not use in that area.

Sir, and that is how all development goes, be it engineering or military (correct me if I am wrong in case of military). Some theories are proven correct and some are wrong. Only time will tell. We should not and can not judge those theories with today's technology. Tomorrow when the technology is there and we can successfully test those theories, only then we can and will judge. Not before that.
And by the way, this is how the technology itself grows. Yesterday's science (hypothesis) is today's technology and today's science is tomorrow's technology.

Any one more thing I wanted to point out is that Einstienian mathematics has not proved Newtonian mathematics wrong. Its just an upgrade or say next version of Newtonian mathematics. In all Einstienian equations of motion, put v << c (which is the case in our normal daily life), and you will reach Newton's equations of motion!!!