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The strangest part of modern physics to me is how inaccessible the concepts are. The terminology and ontology are extremely complex and it seems no one has a gr

The strangest part of modern physics to me is how inaccessible the concepts are. The terminology and ontology are extremely complex and it seems no one has a grasp of the fundamentals like what actually is a photon and what medium is present in a vacuum that allows things like gravity to propagate?

tines 3y ago
The medium for gravity is spacetime, as gravity is not a force but instead just a deformation of spacetime. A photon is an excitation of the EM field.
- RajT88 3y ago
  This was what I was taught in high school.
- svachalek 3y ago
  This is the definition in relativity. They haven't been able to make that idea work in quantum physics, despite it explaining practically everything else, so one theory or the other needs an adjustment.
  - contravariant 3y ago
    My hot take is that they haven't quite been able to make it work for quantum physics either, they just got lucky that their makeshift solution works provided things don't couple together too tightly. Also quantum field theory seems be just plain bad at explaining classical phenomena, which dominate general relativity. To me at least it seems quite difficult to describe a basic electromagnetic from the QFT, other than pointing at the Lagrangian in the path integral and saying something about how contributions outside its extremum will cancel out. Though perhaps I'm simply missing some trick here.
tux3 3y ago
>what actually is a photon It depends what answer you're looking for! We can tell you how photons behave, how to recognize them, and how to predict what they do. For hard philosophy questions, that's more under sections 100-119 of the Dewey Decimal than something physics aims to answer >what medium is present in a vacuum that allows things like gravity to propagate That's a little like asking who is in charge of pushing the sun around the Earth. There's a presupposition in that question, you should first ask why you expect there to be a medium, besides nondescript vacuum
- lacy_tinpot 3y ago
  Isn't a "medium" necessary to establish some kind of causality? Medium just means the means by which objects interact with each other.
  - BobbyJo 3y ago
    Not to mention that there is vacuum energy, which to me (total layman) would indicate that not only is there a medium, but it also has its own influences on the objects within it (like generating Hawking radiation from black hole horizons).
  - tux3 3y ago
    There's different ways to interpret what people expect there to be by an extra medium on top of the vacuum. We can observe and describe stuff interacting. The stuff is positioned in space. We can see that some stuff takes up space, and it can move to take up some other space. What we describe interacting is the stuff itself, the space around it is where it is. Throw an apple through the air, and you can watch it sail through that medium. Remove the air, put it in vacuum, the apple is still able to move around despite the lack of anything meta or extra besides the apple and where the apple is. The story is similar with light, gravity, other phenomenon. Things have some particular location in space, and that location can evolve with time. You can still try to define the word, pick something within that description and call it a medium if you like, but it's not fundamentally necessary. And it won't be something "present in a vacuum that allows things like gravity to propagate". Things propagates on their own, their location within space simply evolves.
CuriouslyC 3y ago
This is because physicists have mathematical models, then try to generate conceptual models based on those which is like trying to describe language to someone by describing the architecture and weights of a LLM.
- piyh 3y ago
  Except for Hawking
  - wongarsu 3y ago
    Not sure if Hawking's method was so different, but he indeed was a great science communicator, on top of being a great scientist.
unsupp0rted 3y ago
The ideas of dark matter and dark energy seems obviously made-up. If a junior dev came to you with that sort of theory for a weird effect they encountered in a system, you'd tell them to look harder instead of making up new fundamental interactions. They may turn out to be right, but you have to admit they sound arbitrarily made-up for lack of a better understanding.
- senttoschool 3y ago
  That's the totally wrong analogy. Dark matter and dark energy are just placeholder names for something we don't understand and don't know what it is. We didn't make them up. We just observe the effects and conclude that there must be something there that is making the universe behave the way it does.
  - BobbyJo 3y ago
    > Dark matter and dark energy are just placeholder names for something we don't understand and don't know what it is. Mostly, but they have a lot of behaviors attached to them at this point due to various measurements and accompanying assumptions. Not to mention that labeling the sets of interactions each exhibit with a single name creates the appearance to the public that they are created by a single source. Dark Matter could be several different things interacting, likewise for Dark Energy.
    - wongarsu 3y ago
      The names also suggest that Dark Matter is matter, and Dark Energy is energy, while there are still scientists that try to find other ways to explain the data (tweaking gravity etc). But you have to name them something to talk about them. There probably would have been better names, but physicists are no better at naming than programmers
    - mrguyorama 3y ago
      Maybe the public shouldn't expect to understand something that takes 8 years of rigorous study to work with, just by reading a news article from someone who also doesn't have 8 years of the necessary math study, and was explained by someone who spends all their time working with these concepts mathematically, and might not have a concrete interpretation at all.
psychphysic 3y ago
Lol dummy the photon is an irreducible representation in the SU(2)×U(1) symmetry group when you rotate it by about 30°. Hope I cleared that all up. Don't ask any follow up questions.
- parasti 3y ago
  This, to me, describes most Wikipedia articles.
  - wjessup 3y ago
    You forgot jumping right into the derivation first without any context of why it matters.
  - mrguyorama 3y ago
    What else could it possibly be? 90% of particle and high energy and quantum physics just doesn't have a real meaning beyond the extremely rigorous math. This isn't classical physics where you can talk about pendulums to twelve year olds, because physics in those domains simply works in more complicated manners. The tools we needed to develop to query that domain simply require more advanced math. IMO, this desire to "simplify" something that cannot really be simplified is why so much pop sci around quantum stuff is just nonsense. Even normal words mean entirely different things in the realm of quantum physics. The layman doesn't understand what quantum computing does because the layman doesn't even have a knowledge of calculus, and all the intuition about the behavior of mathematical systems that comes with it, let alone the kind of linear algebra, discrete math, and higher level math like fields. People need to stop pretending that the most advanced mathematical constructs humankind has conceived, standing on ten thousand years of the smartest minds we have ever birthed, is something that John Q Public can expect to understand. It's no different than me being unable to discuss influences on Picaso's work because I have never taken an art history class. Sure, I could parrot some dumbed down thought someone else feeds me, but I emphatically do not have the context and surrounding knowledge to extract any meaning from that.
kitd 3y ago
That's partly because we're doing it using a brain evolved to hunt prey, track herds or understand seasons, not the subatomic world. The way to deal with that is to use mathematics. Once you yield to its power and give up trying to "understand" particle physics, things are a lot simpler (for certain values of "simple" ofc!)
gsuuon 3y ago
I imagine a photon as being like a glider in the game of life, except the relevant rules are electromagnetism. https://conwaylife.com/wiki/Glider https://conwaylife.com/wiki/Glider
superposeur 3y ago
Actually, the terminology and ontology are astonishingly simple. Electromagnetic waves are ripples in the electromagnetic field, which is a collection of 4 real numbers attached to every point in space and time (the four components of the "4-vector potential"). Gravity waves are ripples in the metric tensor field, which is a collection of 10 real numbers attached to every point in space and time (the independent components of a symmetric 4x4 matrix). The laws of gravity and electromagnetism are a differential equation satisfied by these components governing how they fluctuate from place to place and time to time. Photons are merely quantized ripples in the electromagnetic field (according to quantum mechanics, the momentum and energy in these ripples come in discrete chunks). It's instructive to wonder what could possibly be a simpler ontology. Perhaps one imagines a "medium" like that of sound, consisting of little atoms of some sort spread throughout spacetime. But then immediately this would beg way more questions: what are the atoms themselves made out of? When neighboring "atoms" are displaced why and how do they affect a given "atom" in order to propagate disturbances? What other properties might these atoms have and what would such a word as "properties" even mean since they are supposed to be the elemental constituents of light/gravity itself? According to modern physics, none of this: just 4 + 10 = 14 numbers, no substructure whatsoever. (Of course, there are other fields too, like matter fields and gluon fields and one a necessary part of the whole story is a declaration of what these numbers look like according to different observers, but these features are just elaborations on the basic picture of a collection of numbers attached to events.)

tines 3y ago

The medium for gravity is spacetime, as gravity is not a force but instead just a deformation of spacetime. A photon is an excitation of the EM field.

RajT88 3y ago
This was what I was taught in high school.
svachalek 3y ago
This is the definition in relativity. They haven't been able to make that idea work in quantum physics, despite it explaining practically everything else, so one theory or the other needs an adjustment.
- contravariant 3y ago
  My hot take is that they haven't quite been able to make it work for quantum physics either, they just got lucky that their makeshift solution works provided things don't couple together too tightly. Also quantum field theory seems be just plain bad at explaining classical phenomena, which dominate general relativity. To me at least it seems quite difficult to describe a basic electromagnetic from the QFT, other than pointing at the Lagrangian in the path integral and saying something about how contributions outside its extremum will cancel out. Though perhaps I'm simply missing some trick here.

tux3 3y ago

>what actually is a photon It depends what answer you're looking for! We can tell you how photons behave, how to recognize them, and how to predict what they do. For hard philosophy questions, that's more under sections 100-119 of the Dewey Decimal than something physics aims to answer >what medium is present in a vacuum that allows things like gravity to propagate That's a little like asking who is in charge of pushing the sun around the Earth. There's a presupposition in that question, you should first ask why you expect there to be a medium, besides nondescript vacuum

lacy_tinpot 3y ago
Isn't a "medium" necessary to establish some kind of causality? Medium just means the means by which objects interact with each other.
- BobbyJo 3y ago
  Not to mention that there is vacuum energy, which to me (total layman) would indicate that not only is there a medium, but it also has its own influences on the objects within it (like generating Hawking radiation from black hole horizons).
- tux3 3y ago
  There's different ways to interpret what people expect there to be by an extra medium on top of the vacuum. We can observe and describe stuff interacting. The stuff is positioned in space. We can see that some stuff takes up space, and it can move to take up some other space. What we describe interacting is the stuff itself, the space around it is where it is. Throw an apple through the air, and you can watch it sail through that medium. Remove the air, put it in vacuum, the apple is still able to move around despite the lack of anything meta or extra besides the apple and where the apple is. The story is similar with light, gravity, other phenomenon. Things have some particular location in space, and that location can evolve with time. You can still try to define the word, pick something within that description and call it a medium if you like, but it's not fundamentally necessary. And it won't be something "present in a vacuum that allows things like gravity to propagate". Things propagates on their own, their location within space simply evolves.

CuriouslyC 3y ago

This is because physicists have mathematical models, then try to generate conceptual models based on those which is like trying to describe language to someone by describing the architecture and weights of a LLM.

piyh 3y ago
Except for Hawking
- wongarsu 3y ago
  Not sure if Hawking's method was so different, but he indeed was a great science communicator, on top of being a great scientist.

unsupp0rted 3y ago

The ideas of dark matter and dark energy seems obviously made-up. If a junior dev came to you with that sort of theory for a weird effect they encountered in a system, you'd tell them to look harder instead of making up new fundamental interactions. They may turn out to be right, but you have to admit they sound arbitrarily made-up for lack of a better understanding.

senttoschool 3y ago
That's the totally wrong analogy. Dark matter and dark energy are just placeholder names for something we don't understand and don't know what it is. We didn't make them up. We just observe the effects and conclude that there must be something there that is making the universe behave the way it does.
- BobbyJo 3y ago
  > Dark matter and dark energy are just placeholder names for something we don't understand and don't know what it is. Mostly, but they have a lot of behaviors attached to them at this point due to various measurements and accompanying assumptions. Not to mention that labeling the sets of interactions each exhibit with a single name creates the appearance to the public that they are created by a single source. Dark Matter could be several different things interacting, likewise for Dark Energy.
  - wongarsu 3y ago
    The names also suggest that Dark Matter is matter, and Dark Energy is energy, while there are still scientists that try to find other ways to explain the data (tweaking gravity etc). But you have to name them something to talk about them. There probably would have been better names, but physicists are no better at naming than programmers
  - mrguyorama 3y ago
    Maybe the public shouldn't expect to understand something that takes 8 years of rigorous study to work with, just by reading a news article from someone who also doesn't have 8 years of the necessary math study, and was explained by someone who spends all their time working with these concepts mathematically, and might not have a concrete interpretation at all.

psychphysic 3y ago

Lol dummy the photon is an irreducible representation in the SU(2)×U(1) symmetry group when you rotate it by about 30°. Hope I cleared that all up. Don't ask any follow up questions.

parasti 3y ago
This, to me, describes most Wikipedia articles.
- wjessup 3y ago
  You forgot jumping right into the derivation first without any context of why it matters.
- mrguyorama 3y ago
  What else could it possibly be? 90% of particle and high energy and quantum physics just doesn't have a real meaning beyond the extremely rigorous math. This isn't classical physics where you can talk about pendulums to twelve year olds, because physics in those domains simply works in more complicated manners. The tools we needed to develop to query that domain simply require more advanced math. IMO, this desire to "simplify" something that cannot really be simplified is why so much pop sci around quantum stuff is just nonsense. Even normal words mean entirely different things in the realm of quantum physics. The layman doesn't understand what quantum computing does because the layman doesn't even have a knowledge of calculus, and all the intuition about the behavior of mathematical systems that comes with it, let alone the kind of linear algebra, discrete math, and higher level math like fields. People need to stop pretending that the most advanced mathematical constructs humankind has conceived, standing on ten thousand years of the smartest minds we have ever birthed, is something that John Q Public can expect to understand. It's no different than me being unable to discuss influences on Picaso's work because I have never taken an art history class. Sure, I could parrot some dumbed down thought someone else feeds me, but I emphatically do not have the context and surrounding knowledge to extract any meaning from that.

kitd 3y ago

That's partly because we're doing it using a brain evolved to hunt prey, track herds or understand seasons, not the subatomic world. The way to deal with that is to use mathematics. Once you yield to its power and give up trying to "understand" particle physics, things are a lot simpler (for certain values of "simple" ofc!)

gsuuon 3y ago

I imagine a photon as being like a glider in the game of life, except the relevant rules are electromagnetism. https://conwaylife.com/wiki/Glider https://conwaylife.com/wiki/Glider

superposeur 3y ago

Actually, the terminology and ontology are astonishingly simple. Electromagnetic waves are ripples in the electromagnetic field, which is a collection of 4 real numbers attached to every point in space and time (the four components of the "4-vector potential"). Gravity waves are ripples in the metric tensor field, which is a collection of 10 real numbers attached to every point in space and time (the independent components of a symmetric 4x4 matrix). The laws of gravity and electromagnetism are a differential equation satisfied by these components governing how they fluctuate from place to place and time to time. Photons are merely quantized ripples in the electromagnetic field (according to quantum mechanics, the momentum and energy in these ripples come in discrete chunks). It's instructive to wonder what could possibly be a simpler ontology. Perhaps one imagines a "medium" like that of sound, consisting of little atoms of some sort spread throughout spacetime. But then immediately this would beg way more questions: what are the atoms themselves made out of? When neighboring "atoms" are displaced why and how do they affect a given "atom" in order to propagate disturbances? What other properties might these atoms have and what would such a word as "properties" even mean since they are supposed to be the elemental constituents of light/gravity itself? According to modern physics, none of this: just 4 + 10 = 14 numbers, no substructure whatsoever. (Of course, there are other fields too, like matter fields and gluon fields and one a necessary part of the whole story is a declaration of what these numbers look like according to different observers, but these features are just elaborations on the basic picture of a collection of numbers attached to events.)