Hacker News new | past | comments | ask | show | jobs | submit | jungturk's comments login

Not "same" as in unifying EM and GR, but rather "same" both can be described as geometric regimes in spacetime (though GR be metric compatible and EM in this formulation requiring a relaxation to semi-metricity.

From the conclusion: >Charge is therefore to be understood as a local compression of the metric in the spacetime, which relates to longitudinal waves as described in [12]. This provides some aesthetical features into the model, as electromagnetism seems to be orthogonal to gravity in the sense that current theory of gravity is a theory based on metric compatible connections.


> From the conclusion

From what I can see, this is just a particularly obfuscatory way of saying the same thing I said in response to philipov upthread, where I described how there are different tensors in GR to model gravity and EM. It's not in any way a theory that derives EM from properties of the metric tensor. It adds additional degrees of freedom that aren't in the metric tensor, and then tries to obfuscate what it's doing.


The president appoints new bosses at all the executive branch agencies, and those bosses approve the access.

Several recent news stories have described situations where the agency head resisted and was removed.


This video w/ Dr Iva Fuentes, from two weeks ago, spends a few segments on the breakdown of the equivalence principle w/ quantum clocks.

https://youtu.be/cUj2TcZSlZc?t=4006&si=Ykt0JDqEKk1ObMp3

Video notes have lots of references to relevant papers (and the video itself surveys a few aspects of these issues).


For at least some of the investors, a successful exit doesn't require building a profitable business.


I guess if they can get in early and then sell their stake to the next sucker then they’ll make back their investment plus some multiple. Seems like a Ponzi scheme of sorts. But oh well — looking forward to the HN post about what SSI inc puts out.


Perhaps "outside" means "resident on the boundary of", a la holograms and Maldecena's AdS/CFT work, and so still within reach of experiment?


How is AdS/CFT (as it pertains to describing spacetime & the Standard Model) within reach of experiment? We're not even in an AdS universe.


I was going to write something up but honestly the top two answers in this physics stack exchange do it more competently and comprehensively than I'm able

https://physics.stackexchange.com/questions/122540/why-are-a...

My takeaway/summary is 'AdS/CFT let's you temporarily change your space/model to make the math easier and then map it back into the original model. Although we don't currently have such a model specified for our particular observed universe, it still allows us to study functionality equivalent behavior and make some determinations over what is/isn't/could be possible'


From the link you posted:

> Ok, so if I understand correctly, AdS spaces aren't meant to directly model the universe, but rather are used as a tool to make certain calculations in CFT easier?

GP's comment was modelling the universe as AdS/CFT, though, which is why my question addressed precisely that part:

> How is AdS/CFT (as it pertains to describing spacetime & the Standard Model)


Sorry, my point was to (almost facetiously) interject the topological concept of "boundary/bulk" correspondence (as also exists with holograms & AdS/CFT) rather than suggesting the correctness of AdS/CFT.

The idea that "outside" becomes available via a change in perspective from boundary to bulk.


For those who, like me, are not familiar with AdS/CFT, it's "anti-de Sitter/conformal field theory correspondence" which is "a conjectured relationship between two kinds of physical theories", allowing quantum field theories to be made more mathematically tractable.

https://en.m.wikipedia.org/wiki/AdS/CFT_correspondence


Right - in that story that requisite process has slunk into the background - that "everything is chopping wood" means something quite different to someone who has read all the scrolls, and counseled all the kings, and attained the role of Abbot.

The fact about wood-chopping is the product of enlightenment, not the cause of it.


PTSD and generalized anxiety disorder are very different scenarios, so it wouldn't be surprising that treatments for one wouldn't be effective for the other.

The initial data looks promising in this case, so it'll be interesting to see how the studies develop.


> now wondering...if there's some conserved quantity in the neural network that is _directly analagous_ to conserved quantities in physics

Isn't the model attempting to conserve information during training? And isn't information a physical quantity?


https://www.budgetrewards.com/

Free for a couple months, run by a husband/wife duo as a small business, lots of budgeting in addition to the basic account dashboard and transaction syncing you expect.


_Will be_ available. Rollout is happening slowly.

Tesla's supercharger map shows which stations are open to non-Teslas so far: https://www.tesla.com/findus?v=2&bounds=66.26595543136888%2C...


Consider applying for YC's Summer 2025 batch! Applications are open till May 13

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: