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Hootenanny
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I agree with you, provided that the mass is measured in MeV/c2, or if we're in natural unitsmeteor9 said:so my theory is : E=m
I agree with you, provided that the mass is measured in MeV/c2, or if we're in natural unitsmeteor9 said:so my theory is : E=m
DrGreg said:john 8 keeps asking if time is a "physical thing". He has defined "physical thing" to be either a wave or a particle. So he is asking if time is a wave or a particle.
So I invite everyone taking part in this thread to state explicitly, "no, time is not a wave or a particle" and then maybe john b will stop going on about this and we can discuss something more interesting instead.
Fredrik said:Time is not a wave or a particle.
DaleSpam said:The argument with john 8 appears to be purely semantic. I agree with him tha time is neither a wave nor a particle.
The discussion with meteor9 looks more interesting.
DaleSpam said:Energy is force times distance, force is mass times acceleration, and acceleration is change in velocity over time. So energy is mass times change in velocity over time times distance. So space and time are a fundamental part of the very definition of energy. You will have to do more than just shrug and say that they have nothing to do with each other.
DaleSpam said:So space and time are a fundamental part of the very definition of energy. .
meteor9 said:Energy has nothing to do with time neither with space. Why should the definition of energy refer to time,.
Do you think that "distance along a path" is a thing that is measured by odometers? I'd be inclined to say "yes" to both questions, although I'm not sure if you may have some specific associations with the words "a thing" that I don't.john 8 said:Do you think that time is a thing that is measured by clocks?
Do you think that distance on a path is something that can physically contract? I would say "no" to both. What can happen is that difference in the t-coordinate between two events in a particular inertial frame can dilate relative to the clock time between these events (if both events happen on the worldline of the clock), and similarly if a car is driving along a path that is slanted relative to the x-axis of a coordinate system on a 2D plan, the difference in the x-coordinate between two points on the car's path can contract relative to the distance between these points as measured by the car's odometer (for example, if you're driving on a straight path that's parallel to the x-axis, then when the odometer increases by 10 miles, the car's x-coordinate will also have increased by 10 miles; but if you're driving on a straight path that's at a 60 degree angle from the x-axis, then when the odometer increases by 10 miles, the car's x-coordinate will only have increased by 5 miles). Since both of these are just contractions/dilations relative to a particular coordinate system, I would say that they should not be called "physical".john 8 said:Do you think time is something that can physically dilate?
Do you think that distance along a path is a thing that exists as a specific thing that has special characteristics that identify it as distance? For my own answer, again I am not really sure what you mean by "thing" or "exists" here, so without definitions I'm not sure. But I'll say what I said in post 86 of the other thread, The time along a path through spacetime is at least "physical" if you just mean "there's a well-defined physical procedure for determining the amount of 'time' on a path through spacetime, and this procedure gives a frame-invariant answer" (and of course you can say the same about distance along a path).john 8 said:Do you think that time is a thing that exists as a specific thing that has special characteristics that identify it as time?
Do you think that distance can have an influence on other physical things and yet not be a particle or wave? Again I am not sure because it's not clear what you mean by "influence". I think it makes sense to say that odometers "measure distance" but I don't know if that's equivalent to saying "distance has an influence on odometers", and I'd say the same about clocks and time.john 8 said:Do you think that time can have an influence on other physical things and yet not be a particle or a wave?
It was not wrong, but it was slightly sloppy. Energy is the capacity to do work, and work is force times distance. All the rest follows.john 8 said:First, your definition of energy is wrong.
These are both correct, no work is being done on the wall and no work is being done on the bulldozer. This is freshman-level Newtonian physics. These kinds of problems often stump naive students on first glance. These are both just simply cases of 0% efficiency, where all of the energy being used is used to do internal work (where there actually is force times distance on the molecular or piston level) and generate heat.john 8 said:If we were to apply your definition of energy to the real world it would not jive.
You say energy is force times distance. So watch what happens in the real world according to your definition.
I place my hand on a wall and push against it, I am using a force against the wall. The wall does not move so distance is zero. Force times zero distance equals zero. According to your definition there is no energy being used.
A car pushing against a bulldozer at full throttle, the car and the bulldozer do not move, no distance, so no energy? I do not think so.
The definition of energy is correct. As I noted above I was being sloppy. The definition of work is force times distance (dot product) and all of the remainder of my earlier comments follow.john 8 said:Here is a good definition of energy per “The Essential Dictionary of Science”
Energy; Capacity for doing work. This work may be as simple as reading a book, using a computer, or driving a car.
Please do so then. Any definition of energy using the word "work" involves space and time as a fundamental part of energy as noted previously.john 8 said:DaleSpam, I can site many definitions of energy that do not have space and time as a fundamental part of energy. You have made up your own definition of energy.
A dictionary? Is that where you have your physical knowledge from? How about a physics book? Even wikipedia is OK for such basic stuff, and should clear up your confusion.john 8 said:I suggest that those who want to know the correct definition of force look to a reliable dictionary.
Well, I have always considered math and physics to be very fascinating. And still do. It was all the other subjects that always bored me. Of course most people thought I was crazy. Maybe they're right, but how someone could consider physics boring and literature interesting is way beyond me.meteor9 said:Naty , if physics and maths were not mixed with crazy 'theories' and conclusions , they would be so boring and indigestible.
DaleSpam said:This is a very common claim, but it is simply wrong. Math is the language of logic; if the universe behaves logically then it can be described mathematically. It is as simple as that.
IMO, a non-mathematical treatment of physics is like reading an English translation of Tolstoy. You can get the plot and understand the story, but you miss all of the subtle things that make him great. As divorced from "reality" as our mathematical models are, our verbal descriptions and plain-language models are far worse.
Al68 said:Well, I'll give it a shot. Distance isn't made of particles or waves. Is distance physical?
Time, like distance, isn't composed of particles or waves, but is used to describe intervals between physical events. This is why time is referred to as a dimension, because, like distance, two events can be separated by it. And this simple fact is the reason time (and distance) are useful concepts.
And any useful definition of time will be very similar to a useful definition of distance, in the sense that both are intervals between "physical things", not "physical things" themselves.
So, yes, time is a dimension instead of a substance.
john 8 said:I am not trying to construct a working theory of physics without time. You are adding some requirement to this time discussion. If time was physical then its physicality would not depend on what I thought.
You say time is physical, and have not provided any evidence of how time is physical. If time is physical then it will exist as a particle or a wave. Just explain how you think time is physical.
You need to explain why you think time is physical. The burden of proof lies with you.
My assertion that time is not physical is not speculation, it is based on the fact that there is no evidence to support the idea that time is physical, and the fact that you have not said whether time is a particle or a wave, or given any explanation of how time is physical proves my point. You still have not given any evidence that time is physical.
Lets make this simple. I have told you why I think that time is not physical, you tell me why you think time is physical.
I made lots of posts in this thread, and I honestly don't remember even seeing your original question. The volume of replies here was caused by a number of bizarre claims made by a few individuals, in particular john 8, and most of the thread has been about those things.boysherpa said:Well, I started this thread, and dropped out, and came back to see what had occurred. It is clear that there was no general agreement reached regarding my original question. This original posting was not an idle question, but rather, it was a real question into the way we investigate nature today. The volume of responses indicate that there is some disagreement and confusion regarding time in commonplace and advanced physics.
Yes.boysherpa said:Also, the general level of understanding of the use of mathematical modeling in science seems to be below standards. It is easy to quote equations and their use - but do you understand what they are modeling?
This suggests that there's something lacking in your understanding of the concept of a theory, in particular regarding the connection between the mathematics and the real world. You seem to think that someone who uses an exact mathematical definition is confused and doesn't understand that theories are at best approximate descriptions of reality. This isn't the case at all. Every concept that has any relevance in any successful theory of physics has an exact mathematical definition. This is necessary to ensure that everyone who uses a term like "mass" is talking about the same thing (assuming of course that they understand these things). Also note that a theory can't make predictions about results of experiments involving a concept that's been defined without mathematics). This is because a theory is defined by a set of axioms that tells us how to interpret the mathematics as predictions about possible results of experiments. In particular, if you define "mass" as something other than a mathematical term, the theory isn't making any predictions about it.boysherpa said:To say that mass is defined by mathematics seems to me to be illogical, as the universe does not seem to be run be mathematics. Rather there interacting forces and particles which seem to obey laws and principles. Mathematics is an excellent language to express these laws and principles. Those who view the universe otherwise (run by mathematics) have, to me, an egocentric view of nature. They also normally do not understand mathematical modeling, which is invariably only an approximation to nature.
Fredrik said:This suggests that there's something lacking in your understanding of the concept of a theory, in particular regarding the connection between the mathematics and the real world. You seem to think that someone who uses an exact mathematical definition is confused and doesn't understand that theories are at best approximate descriptions of reality. This isn't the case at all.
Obviously. But we are writing posts on an internet forum, not textbooks. What do you expect? That we write a 10 chapter dissertation rigorously defining each term in response to every idle question?boysherpa said:What I meant to say was that merely stating a mathematical expression is not a definition and cannot explain a physical event or effect ... It is a part of the definition or explanation (or theory), but not the definition in toto.
boysherpa said:So, how can we group time with space? It would seem time is something wholly different, and perhaps not of the same substance.
Any help?