Nature of astrophysics (I) - between theory and observation

[Nereid]

What would the scientists say about their models and theories if we could teleport them from the 18th, 19th and 20th century to nowadays?

They'd have to get used to some new language, for starters!

'Model', for example, is rather recent; even Birkeland did not use it.

By far the biggest change, however, would be for those who were teleported from before ~1905-1930; during that period relativity and quantum mechanics were created/discovered/invented/(or whatever word you think appropriate), and the model of the atom as composed of a small nucleus (with nearly all the atom's mass) and a cloud of electrons (with highly specific properties) burst onto the scene.

Let's take Mr Einstein as example. Would he look at the data acquired by the modern spaceprobes and build a theory or vica versa?

Impossible to say; he was never comfortable with quantum theory, but he didn't live to see some of the amazing experimental tests of it that would likely have caused him considerable consternation (e.g. the various ones on the EPR paradox). I expect he'd have been absolutely delighted to learn of the huge range of experimental and observational results which are now in and which are entirely consistent with General Relativity.

The difference between astrophysics in the 19th century and astrophysics nowadays is the amount of new data we have acquired via spaceprobes. Would this have any influence on the 'nature of astrophysics' ?

I think a far greater difference is the revolution wrought by quantum mechanics ... the detectors and instruments now routinely used, both on the ground and aboard spaceprobes, would have been pure science fiction to almost all 19th century astronomers and physicists.

[webolife]

I've been pondering the thread subtitle: "BETWEEN theory and observation"
Much of my work over the years has involved recognizing what comes BEFORE theory and observation.
I acknowledge at the outset that science is basically a cyclical process; bearing that in mind, I would say that:
1. A theory is built upon the presuppositions/premises/assumptions [beliefs] of the researcher. While all science is predicated upon the basic "misunderstanding" of the researcher, this more elemental issue [what I refer to as the "faith base"] has a deeper and subtler impact on the conclusions made by the researcher.
2. Whether or not it is just a hunch, or a working hypothesis, or a theory previously "established" by a certain amount of evidence, the researcher is either consciously or subconsciously bound by the presuppositions brought to their research. An open-minded researcher is able to or willing to challenge or change those presuppositions, but such changes often involve a major paradigm shift, which can take some time, years or even centuries...
(Astrophysics is particularly subject to this rule, as much of what we observe at a distance cannot be captured and subjected to laboratory scrutiny. But this is what is promising about EU/PC, that the universe may in fact operate according to the same principles we see in the lab.)
3. In light of #1 and 2, a good way to handle such issues is to state them openly, and let peer review take this into consideration as the merits of an explanation are evaluated.
4. Claiming "objectivity" is generally a boast, and not to be confused with the truth of #1. Every observation is made from a particular perspective [or that dreaded word, "bias"], which may not be shared by all observers of the situation.
5. "Objectivity" of observations is best evaluated in the light of stated premises, and truer understanding of the universe is achieved when we recognize differences of perspective. Whether or not we agree with another's perspective, it is honest science to respect it, and expect the same in return. Hence my signature statement.

[Nereid]

Nereid's Question: does picking up the rock mean you have "physically manipulated" it?

Picking up a rock manipulates it if you are testing the effect of its gravitational potential energy. Also, are you replacing it where it was originally or into a new medium such as water? Did you pick it up by hand, in which case you may have removed a small amount of its surface mass, or changing its temperature through conduction? Or did you pick it up with some sort of mechanical device, imparting to it some piezoelectric effects? Perhaps the rock had some radioactive properties that changed its new locale/environment measurably, or removing it from its previous location changed the radioactivity levels in that locale? Did you rotate the rock in any way relative to a local light source so that its luster/reflectivity was guaged, or so that certain included cleavage planes or crystal patterns were revealed? Did you drop the rock after picking it up, inducing all sorts of energy transformations upon impact? Did you pick it up to look at it through any colored filters or polarizing apparatus, or subject it to UV using a black light? For that matter, was the rock outside exposed to weathering elements before you picked it up, affecting changes in the long term processes acting on the rock?

All of which goes to show that 'observation' and 'experiment' cannot really be distinguished by whether there's been 'physical manipulation' or not!

Does any reader think it's possible to make a clear, unambiuous distinction between 'observation' and 'experiment' with respect to physics?

[Nereid]

Every observation is made from a particular perspective [or that dreaded word, "bias"], which may not be shared by all observers of the situation.

I don't really understand this (could you say more please).

Take a typical astronomical observation, say using a CCD-based camera on one of the Gemini telescopes.

The astronomer (or, more typically, the scheduling software, overseen by a someone in the control room) points the telescope to where she wants to go, confirms the pointing, opens/fires up/etc the camera, and starts recording. The raw data is written to tape (or some solid state memory device), which is later 'reduced' by one or more standard software packages, to 'correct for' the known distortions of the camera (e.g. geometric, cosmic ray hits, pixel-to-pixel response variations). The result is written to a file, usually in a format known as FITS, and sent to the astronomer. At some time later, this file may be made available to everyone, by putting it on a public page on the internet (and Hubble Space Telescope observations are always released, after a 'proprietary period', in both raw and processed form).

The FITS format includes meta-data, such as the date, time, and location of the observation.

Where is the perspective, or bias, in such astronomical observations?

5. "Objectivity" of observations is best evaluated in the light of stated premises, and truer understanding of the universe is achieved when we recognize differences of perspective. Whether or not we agree with another's perspective, it is honest science to respect it, and expect the same in return.

An astronomical observation - of the kind I gave as an example above - is objective in the sense that:
a) the data is made available for all to see (and analyse), as well as as much meta-data as anyone wants to know
b) anyone can, in principle, repeat the observation, to check it (in practice this may be quite expensive!).

What "premises" do you have in mind?

[webolife]

Fair enough.
What you are descrbing is what I would refer to as "data". Now the subtle difference I propose is that when we actually "look" at the data, we make the first "observation". The question I would ask in return is, "What is light?" Given the variety of understandings of that basic element of the word "observe", I would say there are an equal number of "observations" possible. I'm talking "before" the conclusions are drawn... is this spot of color simply a chemical reaction in the medium? Or is it an electrochemical impulse in the brain? Or the accumulation of corpuscles being emitted by a distant object? The result of an electrical interaction in an atom? An attribute of space and/or time [eeesh, have to define both of those too if this is the one]? Our way of experiencing "entropy"? Is it something with shape? Energy? A force? Whatever qualities you ascribe to light are key determiners of what you will observe when you look at the data. The way I see it the thought process, even from your perspective, goes like this:
1. Here is this piece of data.
2. Based on what I believe about how light is acting in this situation, here is how I will organize this data.
3. Now that I've organized it, here is what I conclude, or here are some additional questions I have about it.
Our premises drive our questions, frame our hypothesis, tweak our procedure, and lead to our conclusions.
So to answer your other question, no I do not not think there is much of a distinction between observations and experimentation.

[Nereid]

Many thanks.

I think I'm beginning to get what you're saying, and I think it's a topic worthy of its own thread.

In Nature of astrophysics (6) - physics is quantitative, which I have just posted, I mention this idea, and thank you for sparking it!

[MrAmsterdam]

An example of a clash of interpretation (theory) of the same observation

Standard view

View 1 ; What is the vacuum?

http://www.space.com/bestimg/?guid=4499 ... =strangest
Vacuum Energy
Quantum physics tells us that contrary to appearances, empty space is a bubbling brew of "virtual" subatomic particles that are constantly being created and destroyed. The fleeting particles endow every cubic centimeter of space with a certain energy that, according to general relativity, produces an anti-gravitational force that pushes space apart. Nobody knows what's really causing the accelerated expansion of the universe, however.
Credit: NASA-JSC-ES&IA

I'm sure we can find a better description of the vacuum in the standard model. It would resemble the description above. But it seems to point to exotic theories and it cannot be compared to phenomena here on earth.


----------------------------------------------------

My plasma view;

View 2: What is vacuum?

An example of a space medium would be; low pressure plasma, buckyballs and nanotubes (which can be found in abundance in some parts of space).

Empiricisme - scalable comparable phenomena ; look at earth phenomena first

Beyond Batteries: Storing Power in a Sheet of Paper

http://news.rpi.edu/update.do?artcenterkey=2280

Along with its ability to function in temperatures up to 300 degrees Fahrenheit and down to 100 below zero, the device is completely integrated and can be printed like paper. The device is also unique in that it can function as both a high-energy battery and a high-power supercapacitor, which are generally separate components in most electrical systems. Another key feature is the capability to use human blood or sweat to help power the battery.

Rensselaer researchers infused this paper with aligned carbon nanotubes, which give the device its black color. The nanotubes act as electrodes and allow the storage devices to conduct electricity. The device, engineered to function as both a lithium-ion battery and a supercapacitor, can provide the long, steady power output comparable to a conventional battery, as well as a supercapacitor’s quick burst of high energy.

“We’re not putting pieces together — it’s a single, integrated device,” he said. “The components are molecularly attached to each other: the carbon nanotube print is embedded in the paper, and the electrolyte is soaked into the paper.

The researchers used ionic liquid, essentially a liquid salt, as the battery’s electrolyte. It’s important to note that ionic liquid contains no water, which means there’s nothing in the batteries to freeze or evaporate. “This lack of water allows the paper energy storage devices to withstand extreme temperatures,” Kumar said.

From earth phenomena to space phenomena ('the vacuum')

Nanotubes in combination with an electrolyte (plasma?) could create natural mechanisms resembling a battery and supercapacitor. Or in other words; stardust can act like an electric medium.

http://en.wikipedia.org/wiki/Electrolyte
Electrolytes commonly exist as solutions of acids, bases or salts. Furthermore, some gases may act as electrolytes under conditions of high temperature or low pressure. Electrolyte solutions can also result from the dissolution of some biological (e.g., DNA, polypeptides) and synthetic polymers (e.g., polystyrene sulfonate), termed polyelectrolytes, which contain charged functional group.

This is just one description of the properties of plasma, buckyballs, nanotubes and crystals. But really, it's all in the properties plasma medium. We can think of empirical experiments in plasma labs with this view.

What I'm trying to say here is, although everybody is looking at the same picture but we seem to have a different explanations. How come? What chain of reasoning is different here?

It seems to be the same clash if you compare the views on space of Mr Tesla with Mr Einstein.

[mharratsc]

Or are we understanding what we are observing? Are we seeing a 'big picture' of things, or looking at things in isolation?

For instance- what some perceive as "empty space is a bubbling brew of "virtual" subatomic particles that are constantly being created and destroyed", could it not be that we are not perceiving a vacuum in which matter is materializing and de-materializing, but perhaps instead we are perceiving Thornhills 'neutrino aether' that is conducting energy in a wave. If we scrutinize one small zone of the 'vacuum', will we eventually see energy traverse this zone in a wave, and once the neutrinos momentarily 'energize', would they take on the characteristics of subatomic particles for a moment, until the wave passes on and the neutrinos pass back into a quiescent state?

To me, the latter sounds much more plausible that the vacuum 'winking' at me. o.O

[Nereid]

MrAmsterdam,

"vacuum", ""virtual" subatomic particles", "plasma", "pressure", "buckyballs", "nanotubes", "supercapacitor", "electric medium", ...

These are all words whose meaning depends on some theory or other.

Buckyballs and nanotubes, for example, rely upon the idea (theory) that matter is composed of atoms; subatomic particles likewise, and more; plasma, supercapacitor, and electric medium on some theory or other of waves, and electromagnetism (and an atomic theory of matter); vacuum relies upon a much older idea or three, but as a concept it did not exist a thousand years' ago.

Did any of these things exist before the underlying theories were developed (and accepted)?

mharratsc,

What theories, or theoretical concepts, are embedded in "Thornhills 'neutrino aether' that is conducting energy in a wave"?

"If we scrutinize one small zone of the 'vacuum'" - sounds like an observation/experiment; could such a thing be done, without wearing many 'theory' glasses?

[mharratsc]

Did you ever get a chance to read Mr. Thornhill's Electric Gravity in an Electric Universe article?

From the article:

Others and I have argued that a plenum of neutrinos forms the aether.[25] Based upon nuclear experiments, I have also proposed that neutrinos are the most collapsed, lowest energy state of matter. In other words they exhibit vanishingly small mass. However, being normal matter composed of subtrons, they are capable of forming electric dipoles. In an oscillating electromagnetic field a neutrino must rotate through 360˚ per cycle. That would link the speed of light in a vacuum to the moment of inertia of a neutrino. Having some mass, neutrinos must be ‘dragged along’ by gravitating bodies. They form a kind of extended ‘atmosphere’ which will bend light. It has nothing to do with a metaphysical ‘warping of space.’

My thinking was (based upon the notion that 'virtual particles have been seen winking in and out of existence', and based upon Mr. Thornhill's thoughts above) perhaps when a 'virtual particle' is seen "winking into existence", we're actually seeing a momentary energizing of a neutrino into an 'expanded' state, before it passes it's energy along and 'collapses' again.

I was simply attempting to explain the 'virtual particle' observation with Mr. Thornhill's thesis, and seeing if it sounded plausible.

As for an experiment that might prove or disprove... no idea whatsoever. Not sure how they were viewing these 'virtual particles' in the first place. :\

[Nereid]

I think this thread has strayed rather a long way from what I had hoped it would be about.

To bring it back, given that there are 'timing gaps' between theory and observation, observation and experiment, theory and experiment, experiment/observation and theory - per the first post in this thread - what can be said about 'cold, non-baryonic dark matter' (CDM for short)?

Specifically, what can we say - from the perspective of astronomy and/or physics - today, about whether CDM is a Neptune or a Vulcan?

[webolife]

Between the "exotic" and the "just beyond reach"? Between a scientific/testable question and pure speculation?
CDMs, like black holes, are defined by their failure to obey normal physics, therefore any speculation about them need not make any particular physical sense. But when does science become sci fi or vice versa?

[Nereid]

Now this is more of the kind of discussion I was expecting!

CDMs [...] are defined by their failure to obey normal physics

I guess this raises the question of what "to obey normal physics" means.

May we start with "to obey"?

The usual meaning of this word carries a heavy burden of volition, with free will lurking close by. But nothing in physics has free will (as far as I know), so obviously you mean something other than obey as in 'obey the stop sign'.

At the core of normal physics - well, that that I know of - are the symmetries, or conservation laws; mass-energy, momentum, charge, etc.

Does CDM 'obey' these? Is it, perhaps, not invariant under translation under rotation (so would not conserve angular momentum)?

Yes, it most certainly does obey normal physics in this respect.

In fact, it's very much like Neptune before it was discovered, or the neutrino; especially the neutrino, which was proposed to ensure energy and momentum remained conserved in certain beta decays.

But perhaps we have different views of what 'obey normal physics' means?

[webolife]

I re-present my statement as a question, and add:
In exactly what ways does the imaginary cold dark matter fit the symmetries of physics?

[MrAmsterdam]

In order to know the properties of matter, one needs to experiment with matter- empirical observation in labs.

Computer models will generate pixels on your screen.
Math formulas will give a certain outcome on paper or screen.

Could you state the latest results in lab experiments with darkmatter, manipulation of gravity or lightrays bend by gravity?

Space - in vicinity of earth seem to exist of low density, cold ionised gas and dust. Before we start to speculate about far away hypothetical objects and matter, we may want to learn about the properties of such a plasma medium in our earthly labs.

There is more empirical data available about dust plasma then darkmatter. Therefore it seems to be much more logical to think in terms plasma properties then dark matter properties.

Ps the difference between Einstein and Tesla is the following one. Einstein was a theorist working with much less empirical lab data then we have nowadays. Tesla was a theorist and engineer creating his own empirical lab experiments.