Robittybob1

Doesn't even look like me. Stop picking on me! Didn't you pick on me before I patronised you? Now that we've got past that let's get back to the science please. That is the most important question for the day. Parallel to doing this thread I am also studying relativity and the conservation of energy and I'm curious as to what is going on for some terms are not conserved when you change inertial frames. I think we might have uncovered a situation, the odd one out, that can't be explained by relativity. (Note I often get ahead of myself.) Let us do this; if it looks like truly an unusual situation I will start a thread in a more appropriate section of the forum but in the meantime let's see if we can keep it related to the way the Sun cleared the inner solar system during the PMS stage. Agree? I hope I only got negative rep points for patronising and not for lack of effort. If someone disagreed with the physics let they may speak to the forum. So we have this thought experiment going on with the star and this dust particle, and there is no relative motion between them as far as you can tell. You look at the dust and it is not moving, the dust looks at you and it sees you not moving. The thought experiment could be happening in deep space. Now you wouldn't have a problem of two space rockets flying in empty space, with zero relative motion between them, firing laser beams at each other would you? But how do you know those two rockets weren't in actual orbit around each other? OK the gravity will be extremely weak but it must seem weak between the Sun and the particle and because it is orbiting the forces are balanced. Is there a connection here? For in one situation you take aim and fire directly at the target but in the other you figure you need to fire 16 minutes ahead of the target! http://www.scienceforums.net/topic/93429-what-dates-are-accepted-for-the-age-of-the-sun/page-5#entry906944 Which is it?

That was pretty good, and the terminology shows me you do know your stuff, zenith and signal very good. So you were on the Sun firing your laser up to a point that is always at the zenith (copied) Why not just fire it straight up knowing that the momentum of the Sun will go with the signal and carry it to the right place. You know this will happen for at any stage of the signals journey one could look along it one way looking down you will see the origin and looking up you will see the target. It is a series of triangles. Too tired to think - I'll try again tomorrow.

Even so, it is likely to be about mammals. So marsupials are one of the types of mammals. This explains it better than I can. http://www.palaeontologyonline.com/articles/2012/fossil-focus-marsupials/

Was the OP just about mammals? it wasn't clear there is even talk of birds in the OP.

No it was your point that the PMS being too large and too luminous that made me have to rethink the whole idea. Can we time the development of the planets to the stages of Sun development that is the purpose of this thread. It is not hijacked by my answer to your question but that is the ultimate intention of my study (in a general sense) and that is what you asked for. Why do you say that? I'm thinking the same about you. It is not the way to progress. Point out where I'm going wrong if you think I'm wrong, that's more likely to yield results.

How much dust do we need between the PMS and planet Mercury to allow Mercury to be within the habitable zone? That is the amount of dust and that dust must not clear too quickly so that abiogenesis can occur on the inner planets. I have no idea how to express that in particles per m^3

it was to work out how quickly the dust from the debris disk can be cleared. If the dust stays longer the inner planets would be shielded from the radiation coming from the pre main sequence sun. So we are trying to work out if there are 3 mechanisms to clear the dust and in which direction the dust goes. Now we are bogged down on the mechanism of Poynting - Robertson effect. That sounds like you are firing from a stationary Sun. The dust particle in the thought experiment is always directly overhead.

It is like looking at a wonderful landscape. It is another world to explore. I'm going to do it. Bosons - force carriers all words that seem so interesting. Cheers for the lift.

Thanks for attempting the thought experiment. It is a thought experiment where the particle is orbiting the Sun where the Earth used to be, so at that distance it will take year to orbit the Sun. We also engineer the Sun to slow its rotation to match the dust, that is why it can out that far for the Sun has been slowed. (You certainly showed real skill with the LaTex Cheers) So instead of a photon imagine a laser gun on the surface of the Sun. How do you hit the heliocentric particle? Which way do you point the laser? When do you fire the laser, does it help to fire it earlier? No that can't work for it is always directly above. Any angled trajectory would still have a speed of light of c. (The angle the laser is moved away from the vertical is so slight but light speed stays at c.)

That is an interesting question. Marsupials have pouch and a short gestation period, so there would be intermediate species and steps along that process. Maybe pouches on the body for eggs evolving to eggs hatching in the uterus and the very immature foetus hanging on to the dam, to pouches and lactation to feed the foetus, to more mature stages and no pouches. In fact the methods of nutrition of the foetus would have to have developed in unison. https://en.wikipedia.org/wiki/Marsupial

What brand of hair conditioner softener did you use? Does it mention the active ingredients on the label? I have tinnitus too but I have just lived with it and protect my hearing as much as possible. So maybe I'd like to try it one day Did you dilute the peroxide - what strength would you have used?

OK try this thought experiment you have a single dust particle at the distance of the Earth radius and you have the surface of the Sun moving such that one particular dust particle is always directly over the same dead centerpoint (that is a very slow rotating sun 1 year to make 1 revolution. (like a geocentric satellite but over the Sun instead) A photon from a point dead center of the whole set up heads toward the dust particle that is over the dead center point of the Sun. 8 minutes later the photon arrives, is the dust particle still in line with the photon? Will they connect? Personally I couldn't answer that question but you might or someone else might. If it misses the dust what do we have to do to make it strike the dust particle? Does the sideways motion of the Sun remain with the photon during the time it is in space? Above you have "Sun's radiation appears to be coming from a slightly forward direction (aberration of light)" How did that happen? Are saying the photon has no or such a small sideways component that the dust sort of runs into it? With the Sun moving so slowly the surface speed will be nowhere enough to keep up with the dust particle, so I get a feeling the photon has to be angled slightly ahead of the dead center line. But then does that mean the photon will strike the dust with an angle slightly behind? - No because the dust is on a circular path around the Sun the dust will have curved slightly down by the time the photon arrives to strike it midpoint underneath.

So you reckon the incoming radiation doesn't impart any momentum to the dust particle? What principle is that? Conservation of momentum would play a part surely. I'll have a look at it.

Hopefully we learn from our past mistakes. Today the whole world is involved with science, TV, YouTube, Twitter, FaceBook, sites with feedback, science articles freely available on the web, on and on the consensus opinion (peer review) will be enormously powerful.

I was referring primarily to the currently accepted ones (laws of physics) not so much the historic ones. That conservation of energy discussion was peeled off into a separate thread. http://www.scienceforums.net/topic/93590-conservation-of-energy-in-gr-split-from-universal-laws/

It is the orbital velocity if you consider the Sun to be stationary. Then "v" is just the orbital speed but if the Sun is not statioary but rotating by applying relative motion v is the instantaneous velocity difference. OK that is not what the article says but that is the claim of error I am making. It should be relative velocity difference for if the surface of the Sun matched the orbital velocity any photon would not have any aberration diagram (a) or in diagram (b) any photon carrying away more momentum at emission is balanced by the momentum gained by the dust at the time of absorption. Maybe we can't resolve this here. I wonder if someone else would care to comment. Is this the title of the page you linked? Protoplanetary Disk Resonances and Type I Migration or this one? "Poynting–Robertson effect" https://en.m.wikipedia.org/wiki/Poynting%E2%80%93Robertson_effect

See if I can explain my logic to you again. Open this link https://en.wikipedia.org/wiki/Poynting%E2%80%93Robertson_effect#/media/File:Poynting-Robertson_effect.png There are two ways of looking at the cause of the effect diagram A or B. In both cases there is an arrow named "v" which is the relative velocity difference between the Sun and the particle. If that "v" was reduced or brought down to zero or even reversed would that make the P-R effect behave differently? Did you say "yes"? or "no"? I will go on once I know your opinion on the above. Basically I'm asking whether the magnitude of the "v" has a influence on the effect.

In 1905 was special relativity an accepted theory or was it just an hypothesis at that stage? This physics in a minute video goes through the derivation of the famous equation. There was not actual experimentation from the look of it. Did he really use cats? "Einstein's Proof of E=mc²" For clarity can you expand on your ideas so they become clearer to us? Dark energy and dark matter have yet to be fully proven AFAIK so how are you using these ideas as a connection to science being inviolate? I have lost your train of thought sorry. Was there proof of special relativity in 1905? If there wasn't, SR is an hypothesis at that stage, if that is the case you can't say he used scientific theory to derive the energy equation. In that video he says "it follows from his paper on special relativity ...." There is no claim that it was a theory at that stage. There seems to be even another category of ideas called "effects" as in the Poynting Robertson effect. They never say it is anything other than an effect. It seems more like a hypothesis for there is no real proof, as in I haven't read of any experiments to prove it. But there are reasons and formulas that show it could work and it uses ideas very similar to Einstein's radioactive cats. Einstein's first paper was on the photoelectric effect. So how do you overturn an effect? Is that just by showing the laws and theories supporting the cause of the effect have not been applied properly? You would not be claiming the scientific laws are falsified but just their connection/application to the effect is incorrect.

So are you saying that the rotational velocity of the Sun in the Pre main sequence stage (PMS) would have no effect on PR drag? There are plenty who estimate the Sun being much larger and spinning faster during this period. The P-R formula does not have an expression for the rotation rate of the Sun. It seems to make the assumption the rays are emitted from a point source, but in fact the radiation comes from the surface of the Sun and that surface is moving.

How did you take the inviolate bit? "Are there any aspects of physics that are inviolate and absolutely immutable?" https://www.researchgate.net/post/Are_there_any_aspects_of_physics_that_are_inviolate_and_absolutely_immutable The answers there generally point to science is not inviolate. But I must admit I'd be surprised if a law of physics was ever falsified. They have been tested by experiment. Did you agree?

Nothing in science is inviolate. So are you saying Einstein used "scientific theory" to derive his equation when you said "it was an equation derived from theory"?

Are you looking into it? But you are now using the word theory in a different sense as well, you weren't meaning "from other scientific theories" or were you? Google definition of theory Which of the 3 versions did you use? It might the first for I recall it was more based on general principles.

A law and a theory were based on scientific facts that have never been falsified. If they were discovered to be falsified the law is no longer a law and the theory would need revision.

The reason I wrote it that way around was some reference I read yesterday showed a photo of Einstein's handwriting and he had it that way around. It was first presented in a different fashion to what we normally use. But if it was simply an equation we can rearrange the equation. So how do you think Einstein first wrote the expression? Swansont's points are never easy to decipher. Newtonian gravitational attraction is a law and that is written as an equation.

Am I allowed to ask questions in the process of getting it into my head? When Einstein first wrote m=E/c^2 was that simply an equation, a hypothesis, a law or just a theory?