jajrussel

I've started reading about this, and now I'm thinking I should have started reading more about it before I asked.

I was reading another thread that touched dark energy, black hole interaction, among other things. Which led to my thinking and asking these questions of density. One of my thoughts was that I can understand the need for an additional sorce that displays gravity, and usually there are two mentioned, dark energy, and dark matter. In another thread it was said that energy is a property, not a substance. If this is true then dark energy would seem to need a substance in order to be displayed as a property. Truthfully, I was thinking of dark energy as a substance. Dark energy as a property changes the thinking. Originally I had been wondering why the universe needed both dark energy, and dark matter, and if they both existed why would they need to be related. I was viewing dark energy as a substance that might display as matter only under certain special circumstances. Such as extreme density brought about by the only property that seemed apparent, gravity. If I want to continue the thought. I need to stop thinking of it as dark energy because energy is a property, and start thinking of it as a dark substance that only under special circumstances displays both gravity, and perhaps among other things the density of a brick. I have chosen the word substance over matter because it seems assuming one to be the other is best not done. But, are my thoughts about density correct?

This is an interesting article, and pretty much a conversation in itself. It also reminds me that I have thought of virtual mass before when wondering why photons display gravitational interactions. They in the article create a special situation, but I have wondered if the photons that allow me to see a tree are truly reflected, or does the original interaction, cause a photon to be emitted which allows me to see the tree? Or when a photon enters a medium is the photon that exits the medium the same photon for the same reason?

Maybe I am over simplifying, but the concept of density seems simple enough. Take an specific volume of space, add 1 thing to it, and the density for that volume changes. It seems to me that with this concept under the right conditions we could conceivably have a volume of space, of anything, that presents the density of a brick, ( picked arbitrarily ). If my thinking is correct even mass less particles without regard to the probability of the event occuring, should under the right conditions be capable of presenting a volume density comparable to, but not limited to that of a brick? Is this correct?

I am so jealous. Where I work all the work I do is inspected daily. Fail and there is the possibility of a right up. The motivational speech usually goes; (I am glad you showed up. I know you are tired, but it can be dangerous out there,so be careful. We want you to go home the same way we came in, and for God's sake don't do anything foolish. I hate firing people.) Foolish translates to immediately fired. This translates to; (Work faster. Don't screw up or you may get a right up. Enough right ups, then I don't have to worry about firing you. You'll fire yourselves.) Their goal is usually always achieved. We tend to come in tired, and we go home tired. If not for the saving grace that we show motivation by simply showing up, and the fact that supervisors can bend the letter of law with discretion. It would be pure hell. I truely, am so jealous... After reading the other post I forgot that this is about production. Generally when I get to work production is still in the way. This means I am given busy work until I can start my real job. It also means that the number of hours I have to complete my real work changes daily. In my line of work production is based on getting the same job done everyday without regard to how many hours there are left to work with. At certain times certain things have to be done period. If they are not the part of the company that is called production cannot start work. The inspectors have the final say as to when they do start. Production is supposed to stop at specific times. My job is timed around those times. Vary rarely with any accuracy. If I manage to get all my work done no matter what the time limitations are, and it passes inspection before production is supposed to start. I have been productive. Failure is not an option. Failure is the way to unemployment. You live with this mind set every day, or find another job. Forget, and fail to comply with lock out tag out rules just one time results in immediate three day suspension with continued employment pending investigation. The general rule is you don't come back. I have never heard of anyone coming back. There is no supervisory discretion. You don't come back. Self motivation is the natural state of those of us who continue to survive, our production is a given.

Thanks.

Hi, my name is Joe. I tend to be in a state of confusion, or realizing that I am confused. I remember things for quite a while, but forget facts. I make assumtions, and tend to be naive. When I realize that I may have made a mistake of assumtion, I am anal about trying to fix it, but it is usually to late. Apparently, my sense of humor is way too complex, and my communication skills are lacking. Of course it would help if this smart phone was as smart as they advertise it to be. Understanding relativity is on my bucket list. I seem doomed to be the perpetual newbie. And really, the post button is way too close to where my cursor is, or needs to be.

Studiot was right. My reference was to weight. The equation helped to clear up my thinking because the article I read was showing two different equations. When I tried to derive the answer I got two different results one was large one was small. The large answer seemed to be wrong, but I wasn't sure. The reply showed me that the smaller answer was correct, it wasn't that difficult to realize that the 9.8 had beenrounded off to 10. Endy0816's answer did not confuse me,but it did make me smile, actually both times. I have read that even physics people forget that SI rules on occasion. I have also read that physics people on occasion will insist on using SI units even when it is clear that the person they are addressing is clearly confused because they are not. One of the things that confused me was the use of kg for both mass, and weight. Can I assume that some of us English using pounders are not the only ones guilty of confusing a decent physicist by not bothering to learn the language before we attempt a conversation? I'm only joking here. Sort of. Kind of. If we pounders, and Europeans were to refer to weight that is not given in pounds, is there a correct SI unit? And, if I were to start using it, would the metric people admit to knowing what I was talking about. My ex wife could have been a scientist,she hated the word weight. Actually, I hated even approaching the word. Had I used the word mass she would likely now be a widow, rather than my ex wife.

I have been reading about the difference between weight and mass. It is somewhat confusing. If on earth if I weigh 80 kg how do I translate that to mass? On the moon I would weigh less, but the mass remains the same. There is a difference in acceleration, but in terms of energy I am the same?

Okay. Is there an inertia gain?

I am wondering that if it takes force to effect a change in velocity, which we can call acceleration in any form you prefer, why doesn't it take force to change the effect? Any change seems to always be dependant on force. I am sorry, I was not aware that I had defined mass. I do have trouble understanding terms sometimes, but my assumtion is, now that I know a distinction must be made, my meaning should likely be a relative one since I was implying a mass gain through an increase in velocity. At least that is what I thought I was saying. I do admit that, I now accept that in classical mechanics there is no mass gain, but I also have to admit that from a relative point of view that I don't know how that is possible.

I was thinking about anything that shows mass be it asteroid, meteor, or particle. With due consideration to c, as a limiting factor. Though my thoughts dealing with 0 mass particles are not clear to me because I an not sure what to think about them. They seem to exhibit mass, and it is as if they have two states, one of existence, and one of none existence. When they exist they move at c, but can have different energy levels, which seems to present mass which I am assuming would be determined by its energy. My other assumtion is based on the question, what is a photon, or any other 0 mass particle at rest, if not non existent? I am not sure this thought is right? Another question is about photon interaction, when it directly interacts is it absorbed causing a change that emits another photon with perhaps a different energy level,or is the photon that allows me to see the tree in the yard here actually reflected light? I guess if I drew a line between classical mechanics, and relativity I would probably get its exact placement wrong, because I thought mass gain due to acceleration was relevant to both.

Okay, I am wrong again. Energy is not a dimension. ?

In the other thread you cleared up some of my wrong thinking, and gave me new things to consider. Thank you. In this thread I didn't realize I was overlapping analysis methods. Though the thought occurred to me that Newton wise (that if a thing is moving at a constant velocity, unless a force acts on it, it will continue to do so.) Could the same be said for a thing that is accelerating? It doesn't seem that big a leap if no force is acting to stop it, which is why I was wondering if there was a limiting factor in the initial force that caused the thing to accelerate to only a limited degree. Why would it stop accelerating? I confess that it was thinking about Newton mechanics, and Einstein's transfer to relativity that brought the question. Though I have the impression that it was the mention of mass gain that split my analysis methods for you?

Thanks studiot, this changes some of what I thought I knew.

If something is moving at a constant velocity say 10 kilometers per second, and is said to have a specific mass. Then accelerates to 20 kilometers power second, there is a mass gain due to acceleration? And, or due to what accelerated it? If no other force acts on it will it continue accelerating? Or is continued acceleration limited by the initial force that caused it to accelerate? By accelerate in these questions I mean continue to gain velocity.

Dimension / units What is the difference? For instance is mass a dimension where kilograms are it's unit? Is energy a dimension where joules are it's unit?

If you want to learn you have to accept the chance that you might be wrong. I have been in situations where I was certain that I was right only to eventually hear someone say just the right thing that made me go duh! Okay I was wrong. Fortunately, I am not a rocket scientist, and other than being a little embarrassed no harm done. It has happened to me enough times now that that I don't even let it slow the conversation down. Okay you are right, I am wrong, do some cart wheels while I fix it. I thought at first he was referring to dimensionless quantities, and remember reading somewhere that using that concept E=MC^2 reduced to E=M. I will eventually remember where I read it. As an expression it seemed to make sense, but this is a science forum, and as an equation the dimensions are still implied. E is energy, which is measured in joules, and M is mass which is measured in kilograms. As an equation the left side has to equal the right side. Like it or not, one side has to be converted so that both sides are the same dimensionally. If it turns out I am wrong, I still like the direction this thread has taken. I have to go back and reread the last few post. What was it? The universe is accelerating therefore the amount of energy in the universe is increasing, and something else about energy not being conserved? I paraphrase terribly when I can't exactly remember what I've read. I was wondering though, if you guys did this just to get this thread transferred to speculations. I hope you don't plan to just let it die.

Thank you I see my mistake in what I thought. To be specific about my wrong thinking. I was thinking of mass as being a unit of energy. I can picture,and practically feel Gibbs giving me a wake up call.

Asimov: Are you saying that E=M is a dimensionless expression of E=MC^2, where E is said to equal 1, and M is said to equal 1? If this is what you are saying could you explain? I have read that there are reasons for using dimensionless expressions in order to reduce the need for keeping track of different units. Where C=1, G=1. What was the other? I am not sure I remember correctly, hbar=1? I being a newbie, wouldn't these types of expressions normally be used in an equation that expresses at least one type of unit? Truthfully I thought that mass was a unit of energy. So from that view I am not sure at the moment what to think.

In order to get from one place to another place you pretty much have to know where the other place is going to be in the future. How does a worm hole solve this problem?

I find this to be an interesting discussion, though I am not sure of the exactness of the disagreements. E=MC^2 makes a statement, so does E=M. They are not the same statement. As a newbie, and a slow learner certain things tend to confuse me, and the inexactness, or incompletion of a statement can be as confusing as having no idea at all on a subject. I have read that E=MC^2 is a relative term, and that it is a term of proportion. My understanding is that it is a kinetic statement. E=M seems incomplete, simply because something can have energy, yet 0 mass. I have always found this strange, but not entirely unbelievable so long as they stick to the rule. So the statement E=M does not exactly stick to the rule. It implies that anything that has energy has mass, yet ask if a photon has mass, and the answers tend to get really slippery. Does a photon have energy? Yes. Does it have mass? Either no, or it has no rest mass. I thought mass was a kinetic relationship so perhaps at c it has mass, but at rest it has o mass? Well, no, that's the wrong way to think about it, a photon is never at rest it can not be at rest. But, my understanding is that nothing ever stops moving? Well, yes that is true, but when things are at rest their energy and mass at rest are said to be equivalent. Slippery, slippery, slippery. So you apparently need to add something the equation E=M that shows them both to be at rest in order to complete the statement, making it true. And according to Wikipedia E=MC^2 does just that. Again, slippery, slippery, slippery.

The sense I make of this is that nothing can only exist as an adjective of a unit of measure. In order to avoid confusion we have to be like minded in the measure. In use it has to apply to the measure. A charge can be positive, can be negative, or in relation to charge nothing. The term absolute nothing in this sense is like using a double negative in a sentence. It isn't necessary, and adds nothing to the meaning, but confusion. Which is exactly what it is usually meant to do when used rhetorically. However, the term absolute nothing can also imply that the user is confused. This would remove any rhetorical desires of the user to lend weight to their argument. They simply think the term is necessary because, so many others seem to think that it is.

I suppose that if you measure absolute nothing the result would be absolutely accurate?