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Ibix wrote: You really can't do that. That is similar to saying that I cannot make a drawing in only two dimensions. The claim is not to pretend the other dimensions do not exist, rather to provide limits to the scope of thought. A narrower scope often leads to better thinking. Ibix wrote...

Presume we look at a two-dimensional view of space time, with no local masses, and we draw a grid of equidistance spaced lines. The intent is to look at space but not time. As we begin, we look in all directions and the grid lines are evenly spaced. Begin adding mass to the center of the grid...

Tom G, Thanks for the reply. You prompted me to really dig into that formula. I have a workbook that calculates the sun’s noontime elevation for the entire year. Phyzguy, Thanks for your reply. I don’t have Python. I presume your code works, but cramming everything into so few lines with no...

I don't know how to work with vectors that are three dimensional, meaning two angles and a length. I am not interested in the length. The length of the vector to the sun is 93 million miles and the length of the vector representing the panel is infinite. I already did the google search and...

Moved into a house with some solar panels facing due south and some facing due west. Our latitude is 33.8 North in California. We are in the Mojave desert with very little cloud cover. The angle of the roof is 22 degrees from horizontal. What is the equation that will accept the azimuth and...

reply to atyy: No, not comfortable with it. That site does not explain well. It asks question then does not answer. On the second page the author posts the equation d = vt = vf t / 2 Except that the first v has a bar over it. Ok, what is that v-bar. I don't see the explanation. I have been...

I kind of follow along, but have a difficult time. I will look at this some more. In the mean time, my best option is to say that people who understand this have figured it out and we are using the fruits of their labor. If you, the children, want to pursue this I will help, but I will also...

Context! I should have included that in the OP. They do know what square root is, and at least fundamentals of exponents. I am unsure about units, but I do explain that very carefully in the first few sessions on bottle rockets. We spent several of our weeks taking apart gas engines and...

I am a volunteer teaching a STEM class once a week to a class of eight elementary students. From this page http://tbpmindset.org/modules/SECME/Rockets/Rockets_Calculations_Manual.pdf I use this equation for water flow out of a water rocket m = nozzle_area * discharge_coeficient * SQRT( 2 *...

I am going rather slow, spending too much time on Quora. But yes, and I will add in a phrase to consider temperature drop and the resultant further pressure drop. I am doing this because I am a volunteer at an elementary school STEM class, one hour a week. We launched a water rocket a few...

This sounds like trying to help a child learn to ride a bike. Give them a two wheeled scooter to ride for a while. They can step off of it to either side easier than with a bicycle. It will help them learn the concept of steering the scooter/bicycle beneath them to maintain balance. After...

Think about what you "see." The eye connects thousands of rods and cones to the brain and the brain translates those many thousands signals into what we "see." We do not directly "see" the objects we look at, we "see" the image that our brain creates. When the brain receives signals from the...

The document referenced in my previous post provided a formula for mass flow per seconds. After working it for a while the result was 6.98 kg per seconds. With a water load of 0.5 kg, the water rocket is out of water at about the 0.07 second mark. That agrees with our rather imprecise...

Well then. I will shift my reference. I will start here: http://tbpmindset.org/modules/SECME/Rockets/Rockets_Calculations_Manual.pdf and search for a few more. If you have a known good reference, please post. My goal is to enter instantaneous formulas into an Excel spread sheet and iterate...

Point taken. The document is here: http://www.schulphysik.de/strutz/predictors.pdf On the second page, right side, is the equation for flow rate. Is that a valid equation? Do you recommend something different? I am still working the equation and the units are not working out. I will...

Re siddharth: The Newton is the SI unit for force. The nozzle area is 3.8 square cm. Converting that to 0.000308 meters2 does not help much. But OK, I’ll do that. Re Orodruin: No, I am not sure at all. That is what the document says. It can be found with a search for “water rocket...

I found a few questions on water rockets but am not able to understand the equations. The guide I am using has this for the exit velocity of the water: V = sqrt( ( 2 * pressure * nozzle_area ) / water_density ) I plug in the values for my water rocket to get V = sqrt( ( 2 * 17.24Newtons/cm2...

Part of what kicked off my flurry of posts is watching Morgan Freeman narrate "Through the Wormhole." I have watched several of them and find them sometimes, and mostly, fascinating, but also sometimes rather simplistic. Problem is, I am in between competency levels. I played an important...

Saying it in another way, to verify we are on the same page, the ratio of high to low presently found now will be held the same as we run the universe in reverse back to the beginning. If so then yes. Here is another perspective on this idea. As the universe expands and cools, the...

I continue to say that the small differences present today indicate that when the universe was much smaller the differences were much greater. That would mean that there were huge differences from one part of the universe to another. In turn that means that something must account for the huge...

First, I was misconstruing the CMB thinking of it as a measure of temperature. But still, CMB is measured in degrees Kelvin. And that is a measure of temperature. And wasn't the CMB much hotter as we look back closer to the big bang?

In an earlier post I make the controversial suggestion that the universe was very heterogeneous in the early stages. I have another conjecture that goes along with that one. Please try to read this with a bit of an open mind. Imagine that there is an upper limit to the size of a black...

Marcue wrote: In any case Charles Law is no good. Don't have constant pressure, so can't use that. Or so it seems to me. And Chalnoth wrote: Two problems here. First, Charles' Law is only valid for a gas under constant pressure Wikipedia says here...

Hello Ben, Oh, I am certain there is far more that I imagine, let alone understand. Still, given the differences in the CMBR, imagine a giant pair of hands crushing the universe back down to a relatively small size. Little differences will become huge differences. Before running out and...

First, I am a rank novice in cosmology, very rank. However, I do see something that puzzles me. I put some numbers in an Excel spread sheet and I calculate that the early universe was far from homogeneous. I did a few limited searchs and did not find a discussion. Here is what I have...

You missread what I wrote, then did it again. I will stop pursuing this thread and go to my reading. Thanks to everyone for taking the time to reply.

I think something is in error there. If I stand at the fence and move the trolley past me and the fence at 1/2 C, then I should see the trolley be length contacted (while it is moving) and the marks being made 0.866 meters apart. If I hop on the trolley while it wizzes past the fence, the...

Too much to grasp right now There are too many things that don't make sense to me to discuss them all and take up that kind of bandwidth on a forum such as this. I have the Sam Lilley's book "Discovering Relativity for yourself" and am reading that. The problem is I don't take well to...

One little bit at a time if you please. Only if the fence were moving and the trolley not moving. Only if the trolley were moving and the fence is not. Regardless of which is moving, I see no reason why the marks cannot be made at the same time. If one or the other were moving then that...

There obviously is something I am missing. Let's try this. Two markers are one meter apart. The make a mark at the same time. Let's not worry about the mechanics or electronics, or anything about how they are made. Let's presume I cause the marks to be made at the same instance. How can...

Our telescopes receive photons that are upwards of 10 billion years old. That seems to indicate they do not age. According a NASA release found here: http://science.nasa.gov/science-news/science-at-nasa/2002/27mar_stoplight/ photons can be stopped. Regarding the tests on light to coerce...

Hello Janus, Just in case, this is a response to posts 54 and 59 of this thread where you posted your animations: I don’t see anything relationship with relativity. All four examples could be conducted with sound in our atmosphere and obtain the same results. I have been roundly criticized...

I don't know. I am reading all these posts, not understanding many things, trying to find the bits I do understand, and use those bits to leverage an understanding of other bits. I'm just not ready to say anything yet. Please interpret my silence as taking time to think and re-think. I'll...

My apologies, but to create an analogy: I am on the bottom rung of this ladder and you are several steps up. I need to simplify things and understand this bottom rung before I move up. I'll let my recent two posts ride a bit before I continue. Thanks for your patience.

Lets simplify a little bit and go one step at a time. Change the scenario and have the meterstick hovering next to the fence, not moving relative to the fence. The light flashes. The distance between the light and each end of the meterstick is identical. Will the photons at each end of the...

That may well be. I don't think I am with you as I don't see anything to do with relativity. Two lights separated by some distance flash. At some point between the two lights the the light waves cross. Anyone that is in the location will see both lights at the same time. It does not...

No, I pursue it because I see a contradiction in my understanding and in what others say. Are you trying to tell me "Shut up and follow the crowd?"

I cannot follow your point here. I am rather good at the logic of writing code and making systems work, but struggled mightily in Calculus. Please elaborate a few points for me. Please explain the term: the x-coordinate dx. I understand two and three dimensional Cartesian coordinates and...

keeping it simple To All, A problem that I see in open threads like this is that the thread gets fragmented and there are too many points to address at one time. I am not able to keep track of all these concepts simultaneously. I don’t want to short anyone a deserved reply, but I need to ask...

You said the photon would not strike the fence on either side of the meter stick at exactly the same time. I asked what difference that would make. It is very obvious that I intended to ask that question within the framework of my essay. You know perfectly well the intent of my question...

I do not want to go down that path. I want to stay with the reference that Sally provides. She is stationary and moves Tom. He does not know it and the facts show him that he was moving. Let's stay in that frame of reference. One problem at a time please. And it is past bedtime for this...

Do you think its possible I might feel you were rude to me. You went on and on about simultaneity saying it spoiled my theoretical experiment, then when I resolved the problem, you did not recant, did not actually admit I had a point, and did not really address my responses to the simultaneity...

Yes, that is my intent. This is the key to my concept. I do not know how to say this correctly, but I think the reply is to the effect: We switch frames from Tom to Sally, or, Tom and Sally really have the same frame, but maybe the don't know or cannot prove it. Maybe this proves it one...

In the scheme of my essay, how much difference will it make? Don't dodge the question with any nonsense about how it will compare to something else. You made a issue of this. Now answer the question: How much difference will it make?

Given my condition C with the shadow on the fence, just how much difference will it make?

Again, JesseM and I were posting at the some time. I will let that issue ride for a bit and return to the concept of my essay. That is the crux of the essay. My understanding of relativity contains the concept that it says, among many things, that there is no such thing as an absolute...

I was typing and posting at the same time as JesseM and saw this only after I posted. In response: So... I have hit upon a method of conducting my theoretical test. We have dispensed with the issue of simultaneity. The instead of a stick a meter long, we could have a longer stick with...

I will answer your question, but first: Now that you have me all worked up about simultaneity and the impossibility of my experiment, and now that I have provided some conditions that I think resolve the simultaneity problem, please respond to the my last post and we can work our way back to the...

That is getting to the core of the present discussion. I cannot find any reference or reply that says two events must be within X and Y parameters in order to be in the same frame of reference. (You pick the quantities noted by X and Y. Let it be distance, time, or what ever you know to be...

Hello, You guys are saying that simultaneity will make the events of my theoretical experiment unusable. I don't understand why so allow me to ask a few pertinent questions. Given the description of the trolley, how much do you expect the problem of simultaneity to change the marks made by...