Dec 5, 2024 01:35 AM
5 Mathematical Formulas from Ancient Times
https://www.discovermagazine.com/the-sci...ient-times
INTRO: Learn why the achievements of Egypt, Babylon and Greece, though child’s play today, still stand as remarkable feats of intellect.
Most waves need a medium to travel through. But the way that light and gravitational waves travel shows that space can’t be a medium at all.
https://bigthink.com/starts-with-a-bang/...shire-cat/
EXCERPT: . . . Here in the 21st century, our best picture of the Universe is based on quantum fields. In addition to the gravitational field (for which a quantum description has proven elusive so far) and the electromagnetic field, there’s also the weak nuclear field, the strong nuclear field, and the Higgs field, all of which appear to have this same Cheshire Cat-like property: a field without a medium, just like the Cheshire Cat gives a grin without a cat. Interestingly, Einstein — who first gave us this Cheshire Cat for light, whether we liked it or not — grew to hate it. After putting forth general relativity, Einstein instead began to view spacetime itself as a fabric, or in different terms, as a medium.
Was he correct?
We still don’t know. Empty space (or spacetime) is certainly “real” in the sense that it exists; it’s where everything in the Universe lives! We’re certain that a medium isn’t necessary, and that if space itself is such a medium, it doesn’t have any of the traditional properties that we associate with any other known medium. All massless waves — light waves, gravitational waves, even gluon waves — travel at the same speed, as the speed of light and the speed of gravity are equal, but whether this is a hint of an underlying medium or just a fact of reality remains undetermined.
There’s a huge hint against the notion that there is an underlying medium for these waves to propagate through, however: attempts at unifying fields and forces. Back in the early 1920s, Theodr Kaluza and Oskar Klein attempted to unify gravitation and electromagnetism by adding an extra dimension of space. Lo and behold: Einstein’s general relativity and Maxwell’s equation for electromagnetism both popped out! But they were linked together by a new field: the radion. But none of the predicted properties of the radion are borne out by experiment or observation; they must all be removed, somehow, in order to recover the Universe we see.
Other extensions to theoretical physics — Brans-Dicke gravity, grand unification theories, supersymmetry, extra dimensions, string theory — suffer from the same problem. Despite how appealing the idea of a medium is for waves to travel through, the evidence for it not only doesn’t exist, but the evidence we have collected tightly constrains all of these scenarios. There are no scalars in gravity; there is no proton decay; there is only one Higgs boson; there are no relics of extra dimensions; there’s no “bleeding” of electromagnetic phenomena into gravity.
It still may be the case that there is a medium, or some type of unknown aether, that truly does underlie all of reality, but if it does, we have no evidence for it. Nature is telling us that we have waves propagating in our Universe without the need for a medium at all: the most mysterious Cheshire Cat we’ve ever encountered... (MORE - missing details)
https://www.discovermagazine.com/the-sci...ient-times
INTRO: Learn why the achievements of Egypt, Babylon and Greece, though child’s play today, still stand as remarkable feats of intellect.
Most waves need a medium to travel through. But the way that light and gravitational waves travel shows that space can’t be a medium at all.
https://bigthink.com/starts-with-a-bang/...shire-cat/
EXCERPT: . . . Here in the 21st century, our best picture of the Universe is based on quantum fields. In addition to the gravitational field (for which a quantum description has proven elusive so far) and the electromagnetic field, there’s also the weak nuclear field, the strong nuclear field, and the Higgs field, all of which appear to have this same Cheshire Cat-like property: a field without a medium, just like the Cheshire Cat gives a grin without a cat. Interestingly, Einstein — who first gave us this Cheshire Cat for light, whether we liked it or not — grew to hate it. After putting forth general relativity, Einstein instead began to view spacetime itself as a fabric, or in different terms, as a medium.
Was he correct?
We still don’t know. Empty space (or spacetime) is certainly “real” in the sense that it exists; it’s where everything in the Universe lives! We’re certain that a medium isn’t necessary, and that if space itself is such a medium, it doesn’t have any of the traditional properties that we associate with any other known medium. All massless waves — light waves, gravitational waves, even gluon waves — travel at the same speed, as the speed of light and the speed of gravity are equal, but whether this is a hint of an underlying medium or just a fact of reality remains undetermined.
There’s a huge hint against the notion that there is an underlying medium for these waves to propagate through, however: attempts at unifying fields and forces. Back in the early 1920s, Theodr Kaluza and Oskar Klein attempted to unify gravitation and electromagnetism by adding an extra dimension of space. Lo and behold: Einstein’s general relativity and Maxwell’s equation for electromagnetism both popped out! But they were linked together by a new field: the radion. But none of the predicted properties of the radion are borne out by experiment or observation; they must all be removed, somehow, in order to recover the Universe we see.
Other extensions to theoretical physics — Brans-Dicke gravity, grand unification theories, supersymmetry, extra dimensions, string theory — suffer from the same problem. Despite how appealing the idea of a medium is for waves to travel through, the evidence for it not only doesn’t exist, but the evidence we have collected tightly constrains all of these scenarios. There are no scalars in gravity; there is no proton decay; there is only one Higgs boson; there are no relics of extra dimensions; there’s no “bleeding” of electromagnetic phenomena into gravity.
It still may be the case that there is a medium, or some type of unknown aether, that truly does underlie all of reality, but if it does, we have no evidence for it. Nature is telling us that we have waves propagating in our Universe without the need for a medium at all: the most mysterious Cheshire Cat we’ve ever encountered... (MORE - missing details)
![[Image: cyUKpMr.jpeg]](https://i.imgur.com/cyUKpMr.jpeg)
