Gravitational pull of dark matter, and gravity in general.

[TMA_1]

I have a question for you guys. If dark matter (whatever the hell it is, no scientific conjecture seems totally satisfactory to me, but I am a layman at the most when it comes to the various schools of science) has mass enough to gravitationally effect space and time, what happens when visible matter is pulled to the epicenter of these gravitational wells of dark matter? Since dark matter isnt physically affected by normal matter, how is it that dark matter then is affected by the laws of gravity (whatever the hell gravity may really be). Speaking of gravity, is gravity just the reaction to mass in space and time? and if it is a reaction, is gravity more than just an object? It cannot be particulate, yet I have heard that we can indirectly perceive gravity waves, if that is the case then what could gravity be?

Bear with me on how I asked these questions, thanks for the help!

~Titus

[alchemi2]

Speaking of gravity, is gravity just the reaction to mass in space and time? and if it is a reaction, is gravity more than just an object? It cannot be particulate, yet I have heard that we can indirectly perceive gravity waves, if that is the case then what could gravity be?

Bear with me on how I asked these questions, thanks for the help!

~Titus

Physics-Gravity

The natural force of attraction exerted by a celestial body, such as the Earth, upon objects at or near its surface, tending to draw them toward the center of the body OR

The natural force of attraction between any two massive bodies, which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

If that makes any sense to the layman.

[Sneakgab]

It needn't be between ''MASSIVE'' bodies. All particles (ANY object that has mass and volume. Usually used for describing infinetisimal (in terms of volume) objects) exert gravity on each other.

Also, it more correct to refer to the distance between the CENTERS of mass of the two objects as opposed to the distance between their outermost particles.

Gravitational fields are often reffered to along eletrical fields. The refferences are nothing special and are unimportant. They are mostly used to described the potential energy a object possesses as a result of it's position in said field and mass or charge properties (respectively).

I have heard little of dark matter.

I have heard however that the rate at which the universe is contracting does not correlate with the amount of ordinary DETECTABLE matter.

One must assume that dark matter is just undetectable matter (or some substance with mass) that we cannot detect that accounts for the missing matter required for contractive speed (if you will) that has been detected/calculated that the universe is supposedly currently undergoing.

Either the contraction speed detected is incorrect via calculation or defective observational tools, or their is some missing substance with mass to account for the additional contraction.

I suppose scientists have found no error in their calculations and presumably their tools are found to achieving their purpose adequately. Of course tools and cal's have error margins but I'm guessing the difference between the detected values and the values calculated from the amount of detectable mass is outside of their calc error range.

Therefore, the latter possibility (that their is an undetectable substance that contains mass and hence can account for the ''missing'' mass required for the additional gravitational pull to match their readings of the universe's current contraction (or expansion, whatever the case it matters little) speed)

And so, scientists have decided to define a theoretical substance that they have not detected (and supposing they can detect/calc all ''normal'' matter is therefore not normal matter) to account for this mass.

One would imagine those are it's only two properties, that it is currently undectableunobservable and that is has mass (well, maybe 3 prop technically) since those are the only two required to reconcile gravitational theory with experimental data.

Since I hear that it is impossible to detect and observe dark matter I don't see why scientists would attatch any more properties to it's definition since they are not required and therefore doing so would disobey Occam's (entities are not to be multiplied beyond neccesity. Ie: use the simplest system possible that explains the results on the basis of given two valid systems that agree with results you may as well use the simpler system) principle.

Of course, they may have come up with others complications that neccesitate that dark matter does not interact with normal matter. Have you confirmed that this is the current theoretical belief?

Perhaps the addition of dark matter that is experience gravity in kind with it's subject of attraction meaning a moving scource of dark matter would offset predicted system regardless of it's (intending) correcting influence. It's simpler to just say it doesn't move I suppose. It seems more natural, however, to suppose that it does experience gravity like normal matter and then just insert the additional mass into their computer generated predictions.

Perhaps it's an issue of collisions? The dark matter has to be allocated properly and perhaps the different possible allocation (of which their are presumably infinite) all result in collisions that have not been detected? Given the infinite number of possible configurations though, this would seem strange wouldn't it.

Alas, all we can really do is specualte. No doubt we can come up with a working model though, only to have it replaced years later when more anomalies come up.

Such is the way of science, dependent on empirical information that grows progressively less limited hence revealing that earlier theories do not agree completely with experiment. Such is the way of the world:D. To my (generally defunct) memory, the only theory that still agrees within error margins of the latest experiment equipment is that of electrostatics (The one similar to the grav theory. Simple and familiar to all I'm sure). Yet we do not have zero error margins just yet so even this may change.

''is gravity just the reaction to mass in space and time? and if it is a reaction, is gravity more than just an object?''

I'm not sure if it makes sense to speak of gravity as a reaction (since it is continuous and always throughout time) or as an object (no volume or mass). It's simply a law. You could look at it as being a property of an object in a grav field, im that it determines it's pot energy along with other things (such as charge and pos in electrostatic field).

''gravity waves''

Well, I have heard of a theory stating that minute particles travel btw obj's experience gravity and electrostatics. Since scientists are always looking for unification (ie: unified theory), perhaps it seems logical to say that in reality these particles travel btw mass exchanging kinetc/pot energy and momentum via simple collision? This way, perhaps one can do away with the differentiation btw pot grav energy and pot electo energy claiming that it is all actually the exchange of kinetic energy (no initial motion required even, as all is relative and therefore objects appearing stationary relative to each other may in fact be moving with observer... not sure on this). By claiming a law that exchanges energy btw particles governed by said law, ideas of diff pot energy can be eliminated to reduce number of ''entities'' (meaning as in Occam's principle). This seems strange and unnatural though.

Bleh, my wild and perhaps silly speculation is useless to both of us! If you're curiosity will otherwise consume you, it may be best that you simply wiki it or devote you're life to science to find out for you'reself :D

[gryphon]

If that was in laymen's terms I like to know your educated explanation. :)

Basically, matter attracts matter. Dark matter is basically mass that has to be present in order for equations to be correct about the universe. (expansion for one). Although that mass can at this point not be directly detected. Only via calculations that suggest it should be present.

Something like God to create men and Einstein who needed his cosmological constant so his formula's would be correct.

(before we get another topic about that God thing and Einstein keep in mind that this is layman's terms to explain dark matter is to fill a void in formula's / logic we currently miss but "know" which has to be their. Again according to our current interpretations.)

So why does it or doesn't it do something. . we basically don't know what it consists of and what it's properties are. :)

[TMA_1]

thanks guys. It sounds like it is a missing piece to the bigger puzzles in the various schools of physics. I am a bit alarmed, because all of the speculations I have heard about that can account for dark matter seem weak. One example is notion that the gravitational distortion of this can be answered by masses of brown dwarfs. Where in the hell would these brown dwarfs come from though? There would have to be massive quantities of them, and on top of this, it seems to me that brown dwarfs can only be found in a star producing galactic system, and from what it sounds like, the wells of "dark matter" lay outside the galactic webwork of this universe. Dark matter needs serious clarification, the word itself has taken on new ideas, so much so that people assume that it really exists like water exists, when really we only know of its (whatever the hell IT is) existance mathematically and through phenomena like gravitational lensing. who's to say it isnt a fluke in the mathematics caused by a lack of information, or that it is some sort of glitch in spacetime.

and more vague thought-vomit on gravity:

Gravity (whatever it is) reacts to matter, so because of this it must exist. the fact that there are laws on the phenomena of "gravity" shows that it exists. could it be a dimensional thing? could it be a reaction of mass in space and time? that space and time are warped by matter? When you switch from a smooth road to a rocky road, you are going to slow down because the plane you are traveling on is warped, so maybe it is just a law in a sense that it is (bad explanation coming up) like running a finger across a taut sheet. The sheet is the universe and the finger is matter, so matter impacts the fabric of the universe. bleh, dont know if I am making any sense. Thanks though for everything guys.

[Sneakgab]

I think of time as just another dimension, albeit apparently one that has something special about it that sets it apart from the others. I often tend to look at the universe as an infinite amount of ''pictures'' with each picture being a ''snapshot'' of time with all the pictures laid in order. Hence we can refer to time co-ordinately but there is something unusual about it.

People often reffer to warping dimensions and bending the space-time curvature. I know not exactly what they speak of, but judging from the language one imagines that they are speaking about changing the relations between the dimensions. Ie: changing the axial lines of our cartesian system (eg: y-axis is no longer perpendicular to x-axis throughout ''graph'', but the axis curves in relation to the other. Hence, what may previously have been a straight line becomes curved, and curved lines become straight). While I do not know what may cause such warping, the assumption of continously perpendicular dimensions may have been incorrect to begin with, though vector maths assumes and defines otherwise.

''The sheet is the universe and the finger is matter, so matter impacts the fabric of the universe. bleh, dont know if I am making any sense. Thanks though for everything guys.''

That does kind of make sense. Iv'e heard it said that gravity is in fact the result of curved space and time. If these dimensions curve sufficiently then two objects could appear to be brought together when in fact it is only that the space between them is shortening. We imagine a universe whose fundamental laws and nature cannot be changed and hence cannont be impacted by matter or anything else, but never have I heard this proved, it is only an assumption we have been going on because of experience.

Essentially, gravity could be an impaction of space continuum that continously alters it in such a way as to make obj's appear to move be reducing the dist btw them. Alternatively, grav could simply be a law as described earlier that simply is. It is akin to a + b = b + a. It is simply there. The former possibility is more attractive because then it is no longer an axiom. On the other hand, it would directly rely on the axiom of matter impact on the continuum.

This is of course the case with all theories and ideas on ANYTHING. Eventually, they are reliant on axioms of varying degres of reasonableness. eg: it is highly reasonable to say that A is A and not B, that the positive excludes any other possibility (ie: if something is a car, it is not a bird), whereas our matter impactance idea is on far thinner, less intuitive and natural feeling ice.

Hence lies the weakness in the ways of the empiricist: he can only derive his information from his senses which may be deceiving him.

Yet in the case of the rationalist he can come up with alternative theories that may all work.

And so, science attempts to come up with rational theories that agree with empirical date. Still, as we have seen this results in theories that only appear to be correct because our senses have not provided us of evidence of things that would otherwise falsify it.

''who's to say it isnt a fluke in the mathematics caused by a lack of information''

If the theory is confirmed to be a working model, it will be used as though it's real until it is confirmed to be incorrect. This can happening by challenging the validity (whether the theory is correct or not IF it's assumptions are correct) of the theory or the assumptions that the theory is based on. Finally, if an anomaly appears in ''reality'' that does not correlate with the prediction made by theory, then theory will be classified as ''wrong''.

That's not to say it has no use however. Technically Newtons laws of classical physics are ''wrong'', but obviously they are extremely useful within their error margins.

As for these brown dwarfs, I've never even heard them mentioned. If they are regular mass that account for the anomaly then I ask why anyone would want to bother with dark matter?

[alchemi2]

Well it's been a long time since I did basic physics at school but one of the simplest explanations I remember is.

Imagining space as a rubber sheet and the bodies in space as various magnetic metal balls placed upon it, the balls warp the sheet.

What stops the balls rolling together is the reaction of the forces created by spin and rotation.

Rubber sheet = Space.      Forces = Gravity and Time

All mass is attracted to mass but the centricfugal forces repel, this causes motion within a three dimensional environment.

The fourth dimension (Time) is what binds the whole system together allowing flow.

Dark matter is the unseen matter which allows the system to be maintained and continuously expand.