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Thread: Dumb Questions Reborn

  1. #101  
    Bullshit Intolerant PhDemon's Avatar
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    Light itself doesn't have a temperature, as temperature is a statistical.measure of kinetic energy. Photons being massless have a kinetic energy of zero.... But the spectrum of light emitted can tell you the temperature of what is emitting it...

    https://en.m.wikipedia.org/wiki/Black-body_radiation
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  2. #102  
    Bullshit Intolerant PhDemon's Avatar
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    As an addition to the above, whenever you hear of electromagnetic radiation having a temperature (for example the cosmic microwave background radiation), it is shorthand for "the radiation has an energy profile consistent with emission from a black body at that temperature"...
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  3. #103  
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    Quote Originally Posted by zinjanthropos View Post

    Do I have to see/sense it to catch it? I suppose that since there is 'light' producing matter then 'dark' or non-light producing matter isn't too far fetched. Seems to be an opposite to most anything. Might need light producing matter to get a sense of where dark matter could be... idk. Then again, would I need senses in a massless universe.
    Well thought experiments are kosher and so I imagine one could imagine all the possible interactions between known and unknown massless objects and speculate as to whether interaction between any two of them could produce radiation that would interact with another distant massless object.

    I know very little about massless objects but I think all (only?) the force carriers are massless .So that is the photon ,the graviton and the gluon

    So could ,say a graviton interact with a photon and have an effect on a gluon ?

    Or are these force carriers activities limited to their areas of application so that the gravitons only exists(if if does) insofar as it has a bearing on the gravitational field and so would be invisible to em phenomena which would be where photons come in?
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  4. #104  
    Bullshit Intolerant PhDemon's Avatar
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    Well thought experiments are kosher
    But as with real experiments, you only get sensible results if you know what you're doing!
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  5. #105  
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    Quote Originally Posted by PhDemon View Post
    Well thought experiments are kosher
    But as with real experiments, you only get sensible results if you know what you're doing!
    I was thinking of adding "...but they have to be aligned with experimental results eventually"
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  6. #106  
    Time Lord zinjanthropos's Avatar
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    the radiation has an energy profile consistent with emission from a black body at that temperature
    need to find a situation where i can use that line....lol

    Do cosmologists ever ponder that our universe is mixture of two or more universes? Like a universe without mass combining with one that has mass or one is naturally attracted to the other. It always seems to me that mass is like an additive thats spilled into our universe and upset the applecart.
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  7. #107  
    exchemist
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    Quote Originally Posted by geordief View Post
    Did a light bulb go off in your head?

    First catch your massless universe ,perhaps?
    Does your question assume there is mass inside his head?
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  8. #108  
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    Last edited by geordief; May 24th, 2020 at 07:11 AM.
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  9. #109  
    Time Lord zinjanthropos's Avatar
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    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by geordief View Post
    Did a light bulb go off in your head?

    First catch your massless universe ,perhaps?
    Does your question assume there is mass inside his head?
    Never assume anything X-rays of my head show nothing.

    Q: A photon that I missed and didn’t observe goes where....into My future? Universes future? Unless it hits something and bounces back to me then where is it in relation to time?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  10. #110  
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    I have heard often enough that a photon's trajectory is not a valid frame of reference. **
    Perhaps this applies here.


    The way I look at it (though I have been told it is wrong) is that everything is premised on em radiation and to add any qualifications to it is analagous to sawing off the branch on which we are sitting.

    ** perhaps another way of saying "who can say?"
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  11. #111  
    Time Lord zinjanthropos's Avatar
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    Quote Originally Posted by geordief View Post
    I have heard often enough that a photon's trajectory is not a valid frame of reference. **
    Perhaps this applies here.


    The way I look at it (though I have been told it is wrong) is that everything is premised on em radiation and to add any qualifications to it is analagous to sawing off the branch on which we are sitting.

    ** perhaps another way of saying "who can say?"
    Sounds like no one wants to take a shot at it.

    Well if I start chasing the one that just went by then I’m never going to catch it. So it’s not in my future. If it is reflected back to me there’s still a chance I might run into it if there’s enough time. So at that point or any time I catch a photon the past has caught up to me. Seems like the unobserved passing photon just gets to the future before we get there or we never see it again, but it’s still out there. If we see it then it’s In past and if we don’t it’s in the future.
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  12. #112  
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    Well ,I now recall that according to some premise ,(,possibly whether or the the universe is flat or curved on the overall scale) that photon will follow a geodesic that brings it back to its point of origin.


    I think the consensus is that the universe is flat .. so the photon is the photon that could.
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  13. #113  
    Time Lord zinjanthropos's Avatar
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    If there were matter/anti-matter collisions and annihilations would that mean the universe has less mass now then when it began? IOW..can mass be destroyed?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  14. #114  
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    Quote Originally Posted by zinjanthropos View Post
    If there were matter/anti-matter collisions and annihilations would that mean the universe has less mass now then when it began? IOW..can mass be destroyed?
    .
    Doubt we can talk about the mass of the Universe when it began.

    Aside from that I don't know much about mass and matter/ant-matter collisions and anihilations
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  15. #115  
    Time Lord zinjanthropos's Avatar
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    Quote Originally Posted by geordief View Post
    Quote Originally Posted by zinjanthropos View Post
    If there were matter/anti-matter collisions and annihilations would that mean the universe has less mass now then when it began? IOW..can mass be destroyed?
    .
    Doubt we can talk about the mass of the Universe when it began.

    Aside from that I don't know much about mass and matter/ant-matter collisions and anihilations
    Neither do I, that’s why I’m asking I’m a dummy and that allows me to ask. Not like I’m supposed to know. lol
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  16. #116  
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    Well mass is a very interesting subject.

    The last thing I learned about it is that inertial mass (as in Newtonian physics) ie equivalent to gravitational mass (as in Relativity)

    Does this seem relevant at all?

    https://en.m.wikipedia.org/wiki/Mass...ial_relativity
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  17. #117  
    Time Lord zinjanthropos's Avatar
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    I think I’ll leave mass to the experts from here on

    Back to photons, little packets of energy, or so I read. Not sure what the percentages are but it seems likely only a small amount of photons would actually be absorbed by the matter in the universe. Does that mean there’s an unbelievable amount of energy flying around in space?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  18. #118  
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    These photons seem to be "filled" of mutually oscillating waves of the electric and magnetic variety ,where a change in intensity of one causes a change in the other.

    This "internal motion" ,however is not responsible for the trajectory of the photon itself as these waves are perpendicular to the direction of its travel.

    The speed and velocity is established at the "birth" of the photon and I cannot say what creates the initial impulse which presumably sets it on its way.
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  19. #119  
    Time Lord zinjanthropos's Avatar
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    Let’s say you’re observing a object that’s now receding from view >c . At some point there will be no more light emanating from it which would mark the time when c was exceeded. Is the object or the space in between moving back in time relative to the observer?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  20. #120  
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    Are you wondering whether cause and effect can flow in reverse between different frames of reference?

    I have a feeling that this possibility may only be entertained on the quantum level and you seem to have in mind something on the non quantum level(you are talking about the expansion of the universe where galaxies recede from each other at speeds in excess of the speed of light,aren't you?)
    Last edited by geordief; May 28th, 2020 at 08:35 PM.
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  21. #121  
    Time Lord zinjanthropos's Avatar
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    Quote Originally Posted by geordief View Post
    Are you wondering whether cause and effect can flow in reverse between different frames of references?

    I have a feeling that this possibility may only be entertained on the quantum level and you seem to have in mind something on the non quantum level(you are talking about the expansion of the universe where galaxies recede from each other at speeds in excess of the speed of light,aren't you?)
    Yup. Space is expanding faster than light so what happens to time because of this?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  22. #122  
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    I don't know. Are you confident that anything special might?

    Just because we can no longer see something does that mean anything unusual has taken place.

    As someone once said "This too will pass" (maybe it already did
    )
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  23. #123  
    Time Lord zinjanthropos's Avatar
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    Quote Originally Posted by geordief View Post
    I don't know. Are you confident that anything special might?

    Just because we can no longer see something does that mean anything unusual has taken place.

    As someone once said "This too will pass" (maybe it already did
    )
    Just thinking geo.... perhaps space is different. If I was under a dome and it was then lifted straight up, the space I’m occupying would increase dramatically but I don’t think there’s a speed to it.

    Edit: unless it’s 300000 km in every direction per second. That must be the actual distance one truly observes. So if you use 300000km as radius then you could calculate just how big a space that is (volume of a sphere?) visible to anyone in one second.

    Edit...Another thought I have.... There’s a number of air bubbles in motion trapped between two sheets of rubber . They each take up up some space. Occasionally they bump into one another and with each contact the two bubbles become a larger one. Overall space occupied by all the bubbles wouldn’t change but eventually only one will remain. At that point there will be no more expansion of space.

    This is how the mind of the armchair scientist works, that’s why I ask the questions...lol
    Last edited by zinjanthropos; May 29th, 2020 at 01:48 PM.
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  24. #124  
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    If you take the sphere of 1 light second radius around an observer what is actually visible is all the points (events,perhaps) on the surface of that spherical volume.

    You cannot see the volume itself ,only the points within it (and on its surface) that reflect or emit light in your direction.

    If you increase the radius of that sphere to the furthest extent you apparently include objects (such as galaxies) that were created close and closer to earliest time in the universe.

    I am not sure whereabouts on that sphere lie those objects that are receding from the observer at speeds just below that of light and soon to be just above that of light. Perhaps they are somewhere in the middle of that sphere...
    it is a bit confusing.
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  25. #125  
    Time Lord zinjanthropos's Avatar
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    Here’s what confuses me.... if I had 2 lamps, 1 a foot away and the other 300000 km distant and I could see both at same time, that no matter what the physical distance is between me and the two light sources I will in one second receive a one light second length of photons from both. Does that sound correct?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  26. #126  
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    Yes,I think that's right.

    Assuming there is no relative motion between the observer and either lamp -or any strong body of mass along the journey.

    If bodies are at rest wrt each other I don't think the distance of vacuum between them is important except for the delay in the signal.

    I am sure you realize I am just giving my best opinion and Jaunus or Ph could put us right if we are getting this wrong.
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  27. #127  
    Time Lord zinjanthropos's Avatar
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    Realized.

    I’m sure a one second stream of photons can carry different numbers of them depending on medium, intensity, energy etc. Could be wrong on that...idk. Distance from observer doesn’t seem to mean anything. I suppose that makes sense for something that gets to places instantly or without time being a factor. You’d think the universe would be bright as day all the time. Unless you see every photon that exists that’s not going to happen. Can’t remember this paradox...oblers? Funny, I can be in a dark room with an unseen object, somebody could bounce photons off it and I’ll know it’s there otherwise if another object with mass is tossed against it I might not know it until I get hit in the head.
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  28. #128  
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    I think a stream of photons is just a repetition of the emission of one photon


    It is not completely integrated as a stream but it is one after another.(just looks continuous from a distance)

    So the amount of photons emitted at source in a second as measured there would be the same as the number of photons received by the observer provided the observer and the source were at rest wrt each other (no matter the distance)

    I think the object in your dark room will be spontaneously emitting photons all the time so long as it has any internal motion ,as that is what infra red radiation is.

    So I think there is no such thing as invisible objects since they all have a temperature above absolute zero (except possibly dark matter?)
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