pglpm

joined 2 years ago
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[–] pglpm@lemmy.ca 1 points 7 months ago* (last edited 7 months ago)

Completely agree, which I think is very interesting. In Newtonian mechanics, some scalar and vector quantities such as mass, internal energy, contact forces (stress), heat flux are frame-indifferent. Others, such as velocity and acceleration, are frame-dependent but we do have transformation rules for them. Some quantities – and quite important ones – such as momentum, are in a sort of limbo: they are frame-dependent, but there's no clear transformation rule for them.

From the point of view of relativity theory, it's interesting to note that for this particular case of coordinate transformation – note that it is not a Lorentz boost – we can actually calculate the spatial components of momentum in the new coordinate system, if the reported momentum is expressed as a covariant vector (p_µ). This is because its unknown temporal component (energy) gets multiplied by zero in this transformation. But the text is ambiguous on whether the reported components are covariant or contravariant.

[–] pglpm@lemmy.ca 0 points 7 months ago

Regarding the third body, consider the case where its mass is, say, 2 kg, and the case where it's 1 kg instead (the momentum being the same).

[–] pglpm@lemmy.ca 0 points 7 months ago

Yes we're considering Newtonian mechanics in any case. What I'm especially curious about is what physical principles people use to motivate their answers.

[–] pglpm@lemmy.ca 3 points 7 months ago

With one of those spectacular yet "no big deal" moments we were waiting for... 🤣

[–] pglpm@lemmy.ca 6 points 7 months ago

"Science of the Total Environment" journal? 🤣🤣🤣🤣🤣 Too silly even for a 3rd-rate sci-fi film...

[–] pglpm@lemmy.ca 2 points 7 months ago

Cheers! Looks like a great fediverse platform. So sad that the choice of English-speaking servers seems somewhat limited - for now.

[–] pglpm@lemmy.ca 8 points 7 months ago (2 children)

What's Misskey? Never heard of! Time to check.

[–] pglpm@lemmy.ca 11 points 8 months ago* (last edited 8 months ago) (4 children)

these autonomous agents represent the next step in the evolution of large language models (LLMs), seamlessly integrating into business processes to handle functions such as responding to customer inquiries, identifying sales leads, and managing inventory.

I really want to see what happens. It seems to me these "agents" are still useless in handling tasks like customer inquiries. Hopefully customers will get tired and switch to companies that employ competent humans instead...

[–] pglpm@lemmy.ca 5 points 8 months ago

Cheers! Got a bit clearer now.

[–] pglpm@lemmy.ca 20 points 8 months ago (2 children)

Appreciated if someone can explain what is the problem and its context in simple terms 🙏

I understand the GNU "framework" is built on free, open source software. So I don't understand how one can "discover" that there were pieces of non-free software there... They were put there by mistake?

 

cross-posted from: https://lemmy.ca/post/1916423

This insightful blog post seems to refer to this article. I hope the article is an isolated case. Although it's undeniable that scientific illiteracy is spreading.

 

cross-posted from: https://lemmy.ca/post/1916492

cross-posted from: https://lemmy.ca/post/1916423

This insightful blog post seems to refer to this article. I hope the article is an isolated case. Although it's undeniable that scientific illiteracy is spreading.

 

cross-posted from: https://lemmy.ca/post/1916423

This insightful blog post seems to refer to this article. I hope the article is an isolated case. Although it's undeniable that scientific illiteracy is spreading.

 

cross-posted from: https://lemmy.ca/post/1916423

This insightful blog post seems to refer to this article. I hope the article is an isolated case. Although it's undeniable that scientific illiteracy is spreading.

 

This insightful blog post seems to refer to this article. I hope the article is an isolated case. Although it's undeniable that scientific illiteracy is spreading.

1
submitted 2 years ago* (last edited 2 years ago) by pglpm@lemmy.ca to c/busterkeaton@lemmy.ca
 

There's an old youtube channel by "Avamogal" (apparently "a mom to 7 boys. 10 grandkids 8 boys, 2 girls") which is full of great collages of Buster clips, with interesting music backgrounds. Recommended.

Sadly it seems the channel hasn't been active for 6 years or so...

 

I have read the FAQ of KDE Neon: it is well made and answers ground questions like "Is it a distro?" or "Can I turn Kubuntu into KDE Neon?"

...And yet I'm confused, because I'm just a newbie in the Linux world. For instance, when they say "on top of a stable base" I don't know what's meant as a "base".

I think I understand that it isn't a distro, but it fascinates me that it's meant to be installed from an ISO or similar, just like a distro.

I wonder if any of you can explain:

  • What is it, in different words?
  • Why is it "implemented" as it is?
  • Are there any other "quasi-distros" like KDE Neon out there?
  • Do you use it? how has your experience with it been?

Cheers!

 

If I want to link to a community X on a Lemmy instance Y.zzz, I know I should use the link /c/X@Y.zzz, which will redirect to the copy of the instance on the server where the user has the account.

What is the analogous way to link to a post? For example this post has address lemmy.ca/post/1866360 but what link should I give to users on another instance, so that they can see the post in their instance?

 

cross-posted from: https://lemmy.ca/post/1721793

The article introduces a dynamic cosmological constant in the current ΛCDM cosmological model to account for some data from the James Webb telescope. The new model would have the age of the universe at ~27 billion years.

This is interesting. Unfortunately some popular science magazines are already presenting it as a fact...

 

cross-posted from: https://lemmy.ca/post/1721793

The article introduces a dynamic cosmological constant in the current ΛCDM cosmological model to account for some data from the James Webb telescope. The new model would have the age of the universe at ~27 billion years.

This is interesting. Unfortunately some popular science magazines are already presenting it as a fact...

 

The article introduces a dynamic cosmological constant in the current ΛCDM cosmological model to account for some data from the James Webb telescope. The new model would have the age of the universe at ~27 billion years.

This is interesting. Unfortunately some popular science magazines are already presenting it as a fact...

https://doi.org/10.1093/mnras/stad2032

 

Some large datasets are pushing memory and some functions I'm writing to the limit. I wanted to ask some questions about subsetting, of matrices and arrays in particular:

  1. Does defining a variable as a subset of another lead to copy? For instance
x <- matrix(rnorm(20*30), nrow=20, ncol=30)
y <- x[, 1:10]

Some exploration with object_size from pryr seems to indicate that a copy is made when y is created, but I'd like to be sure.

  1. If I enter a subset of a matrix/array as argument to a function, does it get copied before the function is started? For instance in
x <- matrix(rnorm(20*30), nrow=20, ncol=30)
y <- dnorm(0, mean=x[,1:10], sd=1)

I wonder if the data in x[,1:10] are copied and then given as input to dnorm.

I've heard that data.table allows one to work with subsets without copies being made (unless necessary), but it seems that one is constrained to two dimensions only – no arrays – that way.

Cheers!

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