Let's throw some light on Dark Matter

It has been quite a trip to get to this point. Since the journey started with the end point being Dark Matter and Energy. Most things that came by the way have been cleared. So lets begin with some defining lines... In astrophysics and cosmology, dark matter is matter, not directly observed and of unknown composition, that does not emit or reflect enough electromagnetic radiation to be detected directly, but whose presence can be inferred from gravitational effects on visible matter. According to the Standard Model of Cosmology, dark matter accounts for the vast majority of mass in the observable universe. Among the observed phenomena consistent with the hypothesis of dark matter are the rotational speeds of galaxies and orbital velocities of galaxies in clusters, gravitational lensing of background objects by galaxy clusters such as the Bullet cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies. Dark matter also plays a central role in structure formation and Big Bang nucleosynthesis, and has measurable effects on the anisotropy of the cosmic microwave background. All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which interacts with electromagnetic radiation: the remainder is called the "dark matter component". The composition of dark matter is unknown, but may include new elementary particles such as WIMPs, axions, and ordinary and heavy neutrinos, as well as astronomical bodies such as dwarf stars, planets collectively called MACHOs, and clouds of nonluminous gas. Current evidence favors models in which the primary component of dark matter is new elementary particles, collectively called non-baryonic dark matter. The dark matter component has vastly more mass than the "visible" component of the universe.[1] At present, the density of ordinary baryons and radiation in the universe is estimated to be equivalent to about one hydrogen atom per cubic metre of space. Only about 4% of the total energy density in the universe (as inferred from gravitational effects) can be seen directly. About 22% is thought to be composed of dark matter. The remaining 74% is thought to consist of dark energy, an even stranger component, distributed diffusely in space.[2] Some hard-to-detect baryonic matter makes a contribution to dark matter, but constitutes only a small portion.[3][4] Determining the nature of this missing mass is one of the most important problems in modern cosmology and particle physics. It has been noted that the names "dark matter" and "dark energy" serve mainly as expressions of our ignorance, much as the marking of early maps with terra incognita. Well then there is Dark Energy....maybe we take that the next time!

Another perspective of time..

A few months ago I did try to define how time is seen. Below is something that I came upon which is very interesting... While trying to look for a formal definition of time, it is nearly impossible to find one. All we see are examples. I feel a little more needs to be said about time than just that.It appears to me that when we measure time all we are doing is comparing the progress of one motion with another reference motion (or identical copies of it). We usually pick a periodic motion, of some sort, for the reference motion because it automatically sets up its own units for counting, but I think most of us tend to forget what it is we are counting, namely the total number of units of periodic motion the periodic motioner is doing compared to the other motion (activity) we are evaluating. I feel this forgetfulness tends to give time the apparent abstract character of an independent existence which would remain in space after all matter were, somehow, removed.Also, some people postulate the possibility of traveling in time (not just figuratively). We can initiate travel in space, but since time is, apparently, just measured amounts of motion, and motion maintains itself (does its own thing), it seems to me that all we can do aboutmotion (time) is just stand by and watch, and also try to redirect some of this self asserting motion towards our own beneficial uses.Having described what I think time is I would like to mention a couple of complications we run into when logging the times of events. First of all, if observers are scattered around at many different locations they will record different views of the environment for any given point in their common time. If they are far enough apart for the delay in the arrival of light to be significant in there counting of time they will also record slightly different starting times for any events in their ranges of view.What about the effect of the propagation delay of light on the appearance of any simultaneity of events? It is obvious that all observers anywhere on a line equidistant from two events will all agree about the apparent relative simultaneity of those two events.On the other hand, all those observers who are not on a line equidistant from the two considered events will disagree with all those observers who are on the equidistant line, about any appearance of simultaneity. The same goes for any observers who move off the equidistant line during the time of light travel from the two events. (This latter theoretical situation has been erroneously used by some authors as a basis to claim that a different time frame necessarily exists for moving observers, or bodies. A different time frame does necessarily exist for moving bodies, but not because of any altered evaluation of simultaneity, because this also can happen with non moving bodies. Rather is the fact of a different time frame for moving bodies on account of some basic dynamics of physics uncovered by Maxwell and Lorentz, and verified by others.) All the above observers can, of course, reconcile their disagreements by calculating out the delays in the arrival time of light to their locations from the particular events, and arrive at a common "real time" log of the events, providing nobody is moving fast enough to cause the Special Theory of Relativity to become a significant factor. If the Special Theory of relativity becomes a factor then alternate time (rate) frames are set up which can also be calculated out using the Lorentz Transformation, but it is currently considered to be against the rules to call either one of the time frames the only real one. They are both said to be real. However, since most of the matter in the universe, at least "close by", is in the same time frame, I see no reason why we couldn't refer to a "Common Relative Time" and an "Extrinsic Relative Time", the latter phrase being applicable to more than one possible time frame of course. In this way fictitious (or real) super speed space travelers could behooked into a common time system, by using the Lorentz transformation, and agreeing to accept "Common Relative Time" as the basic reference time. That's all the head scratching regarding a description of time I can do right now, but I feel this description is more adequate than I have been able to find in the literature on the subject.

Relative positioning...

It has been a long time since, I sat down and did some serious blogging. The fact is that I have been moving around Europe. Now I need to read my own blog to remember where I last left. In the last few weeks I was inspired to write something. Something very different and not on physics. Take a look at the page. It is just plain silly stupid stuff. It is supposed to be funny. Please visit that site and leave a comment. Would appreciate that. http://swedishstories.blogspot.com/ In the coming days I will get my gray matter back in some order. For all of you who have viewed my blog, thank...keep visiting... PS: By the way, I am in The Netherlands now. It is a wonderful place.

Light Clocks!

Just a small detour here. To understand what I said in the previous post, better lets look at a light clock. Well, what is a light clock? A light clock looks like this one below:

It is a little square carriage made of glass on wheels. At least this one is. Inside there are 2 mirror exactly opposite. One on the floor and the other on the roof. At the bottom mirror there is a light source. If you looked at the diagram it would make it clear in your mind. Yes, we have wheels on it. This is to conduct an experiement that will make it really fun!

We all know that Time= Distance/speed. That means if I was to go 100 miles at 50MPH. The time taken will be 2 Hours to complete that 100 miles. Simple.

In the light clock the distance light travels, is twice the length of the clock. That is light starts at the bottom, goes to the roof and then comes back to the ground. We also know that it will travel at 186,000 miles/second.

With a light clock,

Time= 2L/C. Where L is the hight of the clock and C is the speed of light. Which is 186,000 Miles/Second or 300,000 Kilometres/Second depending on which system of measure you want to use.The above sounds simple, and it is simple. The fun begins when the light clock it self moves. That is where Mr.Lorentz comes in. Again, read the post I had explained that in.

The Second Postulate of the Special Theory of Relativity

The second postulate of the special theory of relativity is very interesting and gives some unexpected results because it plays with frames of references. The postulate is: The speed of light is measured as constant in all frames of reference(If you are unsure as to what frames of references are, go back to a few posts, and I have explained it). Basically it is very similar to the first one, just that it comes out in a different form. If the laws of physics apply equally to all frames of reference, then light (electromagnetic radiation) must travel at the same speed regardless of the frame. This is required for the laws of electrodynamics to apply equally for all frames.

Think about it...it is a very strange and odd one. Here is one fact you can derive from the postulate: Regardless of whether you are flying in an airplane or sitting on the couch, the speed of light would measure the same to you in both situations. The reason that is unexpected is because most physical objects that we deal with in the world add their speeds together. Consider this, car with a driver and passenger is approaching you at a speed of 50 miles/hour. The passenger pulls out a slingshot and shoots a rock 20 miles/hour at you. If you measured the speed of the rock, you would expect it to be traveling at 70 miles/hour (the speed of the car plus the speed of the rock from the slingshot). That is, in fact, what happens. If the driver measured the speed of the rock, he would only measure 20 miles/hour, since he is already moving at 50 miles/hour with the car. Now if that same car is approaching you at 50 miles/hour and the driver turns on the headlights, something different happens? Since the speed of light is known to be 186,000 miles/second, and if we convert that into an hour we get 669,600,000 miles/hour. Coommon sense tells us that the car's speed plus the headlight beam speed gives a total of 669,600,050 miles/hour (50 miles/hour + 669,600,000 miles/hour). The actual speed would measure 669,600,000 miles/hour, exactly the speed of light. To understand why this happens, we must look at our notion of speed.

Speed as we all know is the distance traveled in a given amount of time. For example, if you travel 60 miles in one hour, your speed is 60 miles per hour. We can easily change our speed by pressing or releasing the accelerator in the car. In order for the speed of light to be constant, even if the light is "launched" from a moving object, only two things can be happening. Either something about our notion of distance and/or something about our notion of time must be out of line. If we look at what really happens it turns out, that both are lot of line. Remember, speed is distance divided by time. Think about it, and you will know what I am saying.

That is enough to think about for the time being. I am going to introducing this very gently, just to make sure our gray matter does not get into a twist!!

Relatively Mythical stuff....

Just to clear the air about somethings. Special Relativity is a playground for the mind. However, it is not some of the things I have listed below. 1. Time slows down as speed increases. Remember, we were talking of reference frames. Within a single reference frame that does NOT happen. Only when one reference frame is viewsed from another does all this take place. What that simply means is that on earth time never slows down as speed increases! 2. Objects get shorter as speed increases. The same rule as above applies here. 3. Special Relativity does not handle acceleration. That is the biggest myth about SR. 4. Mass increases with speed. In reality it is energy that increases and not the rest mass. 5. Nothing travels faster than the speed of light. What SR says is that crossing the light barrier either from a faster or slower speed is not allowed.

The long and Winding Road to Relativity

I started this blog to work on Dark Energy and Dark Matter...from there I skipped to relativity with one's grandmother playing a role. Let me explain, for one to understand Dark E and M, it is best that relativity be understood to some extent. My final goal is to hit on Dark E and M. Between that relativity and a few other stories might come in. For the time, we will focus on relativity. Just to remind readers that I have not 'lost the plot'

Relatively Thinking...

A good place to start maybe is to understand the first postulate...where on earth do I start? Frames of reference is what we need to understand. Let me find a grand mother to explain this to. Will be back!