• christian2017
    1.1k
    If max speed of light (C) is constant does that mean measurements are consistent?

    max speed of light (C) = 299792458 metres per second

    I would argue an electron and proton is a certain size and that to a certain extent a ruler bought at walmart is a certain size.

    I've seen people argue that there is no absolute points in space.

    If C is always the same that implies measurements are accurate and that there is absolute points in space (it least in most if not all senses or "levels")

    Am I missing something?
  • aletheist
    1.3k
    If C is always the same that implies measurements are accurate and that there is absolute points in space (it least in most if not all senses or "levels")christian2017
    I do not see how that follows at all. The speed of light in a vacuum is constant regardless of whether or how we measure it, suggesting that continuous motion through spacetime is a more fundamental reality than discrete positions in space or discrete instants in time treated separately. A meter is an arbitrary unit of length, and a second is an arbitrary unit of duration. A material object traveling at half the speed of light relative to an observer would be measured by that observer as shorter than the same thing not moving at all relative to that same observer. The uncertainty principle is that it is impossible even in principle to measure both the velocity and position of a particle to the same precision at the same designated instant.
  • tim wood
    4k
    A material object traveling at half the speed of light relative to an observer would be measured by that observer as longer than the same thing not moving at all relative to that same observer.aletheist

    Shorter.
  • christian2017
    1.1k
    If C is always the same that implies measurements are accurate and that there is absolute points in space (it least in most if not all senses or "levels")
    — christian2017
    I do not see how that follows at all. The speed of light in a vacuum is constant regardless of whether or how we measure it, suggesting that continuous motion through spacetime is a more fundamental reality than discrete positions in space or discrete instants in time treated separately. A meter is an arbitrary unit of length, and a second is an arbitrary unit of duration. A material object traveling at half the speed of light relative to an observer would be measured by that observer as shorter than the same thing not moving at all relative to that same observer. The uncertainty principle is that it is impossible even in principle to measure both the velocity and position of a particle to the same precision at the same designated instant.
    aletheist

    Doesn't speed/velocity require a standard unit of distance measurement over a standard unit of time? I understand that if two clocks are hurdling through space at different velocities the faster moving clock will tell time slower than the slower moving clock.

    I actually never heard Stephen Hawkings nor my Physics professor in college say there is not absolute points in space. Do you have an article on this?
  • christian2017
    1.1k
    I do not see how that follows at all. The speed of light in a vacuum is constant regardless of whether or how we measure it, suggesting that continuous motion through spacetime is a more fundamental reality than discrete positions in space or discrete instants in time treated separately.aletheist

    Treated separately by who? Stephen Hawkings nor my Physics Professor ever said that there were not absolute points in space. I understand that some things should be treated separately but just as in a mathematical proof if you want to prove that two things can be treated separately you have to prove that they can be treated separately

    I feel these two things have a close relationship to each other. Perhaps i'm wrong.
  • christian2017
    1.1k
    A material object traveling at half the speed of light relative to an observer would be measured by that observer as longer than the same thing not moving at all relative to that same observer.
    — aletheist

    Shorter.
    tim wood

    Not saying you are wrong but "by that observer as shorter", are you referring to the length of the material object? I'm familiar with this sort of phrase but Physics isn't something i study all day so could you unpack or rephrase that slightly?
  • christian2017
    1.1k


    Thanks for the videos. It will take me a while to watch them.
  • aletheist
    1.3k
    Doesn't speed/velocity require a standard unit of distance measurement over a standard unit of time?christian2017
    Not at all; the separation of space and time, with basic units assigned to each, is an arbitrary convenience. Presumably it reflects the fact that we can directly measure them more easily than velocity. Nevertheless, we could (and arguably should) instead treat velocity as primary and derive our units of distance and duration accordingly. In fact, that is how we get the Planck length and Planck time, the smallest measurable units of distance and duration.

    I actually never heard Stephen Hawkings nor my Physics professor in college say there is not absolute points in space.christian2017
    What exactly do you mean by "absolute points in space"? My contention all along has been that space is not composed of points and time is not composed of instants. We artificially mark points in space and instants in time for purposes such as measurement.
  • christian2017
    1.1k


    I watched the first video.

    I feel the following adds to the problem (this was taken from one of the people who made comments)

    These examples always assume physical matter can retain its form when at that speed. That is the only flaw. Molecules start to break apart at that speed so the barn, her pole and the girl herself will not be a solid object anymore. -Jeff

    I think once you are dealing with waves, gases and an array of particles that does change test results. I'll get back to you unless ofcourse you provide more information.
  • christian2017
    1.1k
    Nevertheless, we could (and arguably should) instead treat velocity as primary and derive our units of distance and duration accordingly. In fact, that is how we get the Planck length and Planck time, the smallest measurable units of distance and duration.aletheist

    The equation for velocity is distance divided by time. I'm still confused. I'm only familiar with Calculus and Algebra.
  • christian2017
    1.1k
    I actually never heard Stephen Hawkings nor my Physics professor in college say there is not absolute points in space.
    — christian2017
    What exactly do you mean by "absolute points in space"? My contention all along has been that space is not composed of points and time is not composed of instants. We artificially mark points in space and instants in time for purposes such as measurement.
    aletheist

    Good we agree on that. This forum topic was in response to someone elses forum topic a week ago. It appears we agree on that. If it sounds stupid its because i was quoting someone elses phrase.
  • Nobeernolife
    487
    Am I missing something?christian2017

    I think you are missing the entire science of quantum physics. Not that I claim to understand it, but listen to some lectures on that topic and have your mind boggled.
  • christian2017
    1.1k
    Am I missing something?
    — christian2017

    I think you are missing the entire science of quantum physics. Not that I claim to understand it, but listen to some lectures on that topic and have your mind boggled.
    Nobeernolife

    Not all Quantum Physicists agree, and many like to claim QM supports post-modernism. I have read some articles and watched some videos on it. I don't think 90% of these Physicists understand it. I think 10% do but they can't outright prove it.

    But this forum is for amatuers for the most part so i will continue like every one else as an armchair quarterback.
  • tim wood
    4k
    These examples always assume physical matter can retain its form when at that speed. That is the only flaw. Molecules start to break apart at that speed so the barn, her pole and the girl herself will not be a solid object anymore. -Jeffchristian2017

    You have to ask Jeff how he knows the barn and the pole are moving.
  • christian2017
    1.1k
    These examples always assume physical matter can retain its form when at that speed. That is the only flaw. Molecules start to break apart at that speed so the barn, her pole and the girl herself will not be a solid object anymore. -Jeff
    — christian2017

    You have to ask Jeff how he knows the barn and the pole are moving.
    tim wood

    Thats fair. Arguing about physics when we are amatuers is fun. Even when things get indepth on this forum they never get past pop culture physics books.

    Jeff invited me over for dinner tommorow. Did he invite you?
  • tim wood
    4k
    I think the point made in a number of videos made by responsible and knowledgeable scientists on Youtube is that it is very easy to make mistakes in relativity. Among the problems is the need to be precise in definitions. And I know this first-hand from schoolwork. An example of the mistakes that can be made is at hand:

    I think you are missing the entire science of quantum physics. Not that I claim to understand it, but listen to some lectures on that topic and have your mind boggled.Nobeernolife

    The subject is relativity, not QM. He might as well have mentioned Egyptology. And relativity is understandable. QM is not.
  • christian2017
    1.1k
    I think the point made in a number of videos made by responsible and knowledgeable scientists on Youtube is that it is very easy to make mistakes in relativity. Among the problems is the need to be precise in definitions. And I know this first-hand from schoolwork. An example of the mistakes that can be made is at hand:

    I think you are missing the entire science of quantum physics. Not that I claim to understand it, but listen to some lectures on that topic and have your mind boggled.
    — Nobeernolife

    The subject is relativity, not QM. He might as well have mentioned Egyptology. And relativity is understandable. QM is not.
    tim wood

    I guess part of my problem with some of what is being said on this forum topic is does it all line up with what Einstein or Hawking would say.

    Sometimes things are misinterpreted based on details not being considered or known by the person talking/writing.

    aletheist actually confirmed my main issue. He agrees atleast as far as i can tell that there is absolute points in space. If he doesn't agree with that then i guess i misinterpreted what he said.

    I'm currently reading Einstein's book called "Relativity". It will probably take me 2 years to read that book.
  • tim wood
    4k
    there is absolute points in space. If he doesn't agree with that then i guess i misinterpreted what he said.

    I'm currently reading Einstein's book called "Relativity". It will probably take me 2 years to read that book.
    christian2017

    You have to ask what makes an absolute point different from an ordinary point. The answer is nothing: there are no absolute points. There are reference frames, but like a well-known piece of anatomy, everyone has one.

    If your book is short, with short chapters, that's an excellent book. If it has an appendix #5, that's even better. That appendix did not survive into subsequent editions.

    Relativity (and QM, as i happens) are among the better verified things on earth.
  • christian2017
    1.1k
    there is absolute points in space. If he doesn't agree with that then i guess i misinterpreted what he said.

    I'm currently reading Einstein's book called "Relativity". It will probably take me 2 years to read that book.
    — christian2017

    You have to ask what makes an absolute point different from an ordinary point. The answer is nothing: there are no absolute points. There are reference frames, but like a well-known piece of anatomy, everyone has one.

    If your book is short, with short chapters, that's an excellent book. If it has an appendix #5, that's even better. That appendix did not survive into subsequent editions.

    Relativity (and QM, as i happens) are among the better verified things on earth.
    tim wood

    Well once i read the book, i can confirm what you are saying. I've read pop physics books that contradict Stephen Hawkings. For whatever reason i like Stephen Hawkings because he makes me think hes right. Not all pop physics books are correct, atleast as far as i can tell. Based on my observation, some pop physics books contradict other pop physics books.
  • SophistiCat
    1.1k
    Treated separately by who? Stephen Hawkings nor my Physics Professor ever said that there were not absolute points in space.christian2017

    I can readily believe that they never said that, because they wouldn't even know what that means. You can't even explain what you mean, so I suspect that you don't know what you mean either.

    I'm currently reading Einstein's book called "Relativity". It will probably take me 2 years to read that book.christian2017

    It's a popular book aimed at non-physicists, so you shouldn't have so much trouble with it. But I think you (and Jeff from Youtube) should start from the basics: non-relativistic classical physics. For instance, the question of what it would be like for someone to move at a constant speed - whether they would feel any different than if they were staying put - was considered by Galileo back in the 17th century. Einstein only refined that treatment, but to understand what Einstein did and why, you first need to understand Galilean relativity.
  • christian2017
    1.1k
    Treated separately by who? Stephen Hawkings nor my Physics Professor ever said that there were not absolute points in space.
    — christian2017

    I can readily believe that they never said that, because they wouldn't even know what that means. You can't even explain what you mean, so I suspect that you don't know what you mean either.
    SophistiCat

    I addressed this with someone else and we came to a conclusion. I'm smarter than you cat. Don't be so mean, you hurt my feelings.
  • christian2017
    1.1k
    I'm currently reading Einstein's book called "Relativity". It will probably take me 2 years to read that book.
    — christian2017

    It's a popular book aimed at non-physicists, so you shouldn't have so much trouble with it. But I think you (and Jeff from Youtube) should start from the basics: non-relativistic classical physics. For instance, the question of what it would be like for someone to move at a constant speed - whether they would feel any different than if they were staying put - was considered by Galileo back in the 17th century. Einstein only refined that treatment, but to understand what Einstein did and why, you first need to understand Galilean relativity.
    SophistiCat

    I took Physics and Calculus. I'm aware of what Galilean relativity is as far as i understand Galilean relativity.

    Specifically, the term Galilean invariance today usually refers to this principle as applied to Newtonian mechanics, that is, Newton’s laws hold in all frames related to one another by a Galilean transformation. In other words, all frames related to one another by such a transformation are inertial (meaning, Newton's equation of motion is valid in these frames). In this context it is sometimes called Newtonian relativity.

    Among the axioms from Newton's theory are:

    There exists an absolute space, in which Newton's laws are true. An inertial frame is a reference frame in relative uniform motion to absolute space.
    All inertial frames share a universal time.
    Galilean relativity can be shown as follows. Consider two inertial frames S and S' . A physical event in S will have position coordinates r = (x, y, z) and time t in S, and r' = (x' , y' , z' ) and time t' in S' . By the second axiom above, one can synchronize the clock in the two frames and assume t = t' . Suppose S' is in relative uniform motion to S with velocity v. Consider a point object whose position is given by functions r' (t) in S' and r(t) in S. We see that

    I have no problem with this.

    We can't have all went to an expensive french school cat.

    I assume you've taken Calculus or several Calculus classes?
  • aletheist
    1.3k
    aletheist actually confirmed my main issue. He agrees at least as far as i can tell that there is absolute points in space. If he doesn't agree with that then i guess i misinterpreted what he said.christian2017
    No, I do not agree with you. Here again is what I said.
    What exactly do you mean by "absolute points in space"? My contention all along has been that space is not composed of points and time is not composed of instants. We artificially mark points in space and instants in time for purposes such as measurement.aletheist
    Points in space and instants in time are our creations. They do not exist apart from our designation of them; i.e., they are not real, which is what I take you to mean by "absolute" unless you clarify otherwise.
  • christian2017
    1.1k
    aletheist actually confirmed my main issue. He agrees at least as far as i can tell that there is absolute points in space. If he doesn't agree with that then i guess i misinterpreted what he said.
    — christian2017
    No, I do not agree with you. Here again is what I said.
    What exactly do you mean by "absolute points in space"? My contention all along has been that space is not composed of points and time is not composed of instants. We artificially mark points in space and instants in time for purposes such as measurement.
    — aletheist
    Points in space and instants in time are our creations. They do not exist apart from our designation of them; i.e., they are not real, which is what I take you to mean by "absolute" unless you clarify otherwise.
    aletheist

    thats fair. you don't agree. Can a galaxy that is traveling through space at some point in time occupy the same space that another galaxy (there are many galaxies) used to occupy? I'm not saying i know the answer to this but i was wondering what your answer was?
  • aletheist
    1.3k
    Can a galaxy that is traveling through space at some point in time occupy the same space that another galaxy (there are many galaxies) used to occupy? I'm not saying i know the answer to this but i was wondering what your answer was?christian2017
    Since we invent points and instants as needed for any particular purpose, it depends on how we define them. If we set up a three-dimensional coordinate system for space only, then I suppose that the answer is yes--different things can occupy the same point at different instants. If we set up a four-dimensional coordinate system for spacetime (block universe), then I suppose that the answer is no--only one thing can occupy any individual point-instant.

    I ask again: What exactly do you mean by "absolute points in space"?
  • christian2017
    1.1k
    Can a galaxy that is traveling through space at some point in time occupy the same space that another galaxy (there are many galaxies) used to occupy? I'm not saying i know the answer to this but i was wondering what your answer was?
    — christian2017
    Since we invent points and instants as needed for any particular purpose, it depends on how we define them. If we set up a three-dimensional coordinate system for space only, then I suppose that the answer is yes--different things can occupy the same point at different instants. If we set up a four-dimensional coordinate system for spacetime (block universe), then I suppose that the answer is no--only one thing can occupy any individual point-instant.

    I ask again: What exactly do you mean by "absolute points in space"?
    aletheist

    Ok great! I agree with that.

    Have you ever seen the youtube video "10 dimensions explained"?

    Absolute points in space? Why are you asking that? Look it up on google or if you can wait an hour or two i'll come back from something i'm doing, i'll explain what i meant by that. brb.
  • christian2017
    1.1k
    I ask again: What exactly do you mean by "absolute points in space"?aletheist

    as i told another person on another post, the phrase is something i got from another forum topic. Basically the whole question earlier that you answered for me about the moving galaxies was the basic premise. Can two galaxies have ever occupied the same absolute points in space? You answered that question and i would like to thank you.
  • aletheist
    1.3k
    Can two galaxies have ever occupied the same absolute points in space? You answered that question and i would like to thank you.christian2017
    I did not answer that question, because I said nothing at all about absolute points, because you still have not explained exactly what you mean by that term. Coordinate systems are arbitrary and artificial intervals marked off relative to an arbitrary and artificial origin, so there is nothing absolute about the points that they define.
  • christian2017
    1.1k
    Since we invent points and instants as needed for any particular purpose, it depends on how we define them. If we set up a three-dimensional coordinate system for space only, then I suppose that the answer is yes--different things can occupy the same point at different instants. If we set up a four-dimensional coordinate system for spacetime (block universe), then I suppose that the answer is no--only one thing can occupy any individual point-instant.

    I ask again: What exactly do you mean by "absolute points in space"?
    aletheist

    I didn't come up with the term absolute points in space so i'm not going to give an exact definition.

    I couldn't find one on the internet.

    I'm not sure why you are asking since i agree on the above paragraph you stated and once again i didn't come up with the phrase. And once again for the 3rd time i agree with the above paragraph.

    Absolute points in space is the spot on my desk where my pencil is resting can in the future be occupied by another object and also possibly be the approximate center of another galaxy far far away at some point in the future.

    Since i didn't come up with the phrase (once again), and the concept seems fairly simple, i hope that definition is good enough for you.

    Why do you ask? And once again i agree completely with the above paragraph you stated. Stop trolling me and/or add information to the conversation.
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