I ask this question because of this comment chain (and totally not because I got down voted and my ego is too fragile, it is most definitvely absolutely positevly me asking for the science. I swear)

https://lemmings.world/post/23635250/14708515

If you can go through it, please do, there are some references for some claims, if not you can go through the following ai generated summary (if it helps, it is a local llama)

The original poster (sga) expressed concerns about the practice of trimming cat nails, comparing it to declawing and suggesting that it may cause trauma for the cat. Other users (Bamboodpanda and Chairman Meow) responded that trimming cat nails is a normal and necessary practice, especially for indoor cats, to prevent overgrown nails and damage to furniture. sga argued that cat claws are an essential part of a cat’s predatory nature and that trimming them may impair their ability to hunt and defend themselves. Chairman Meow countered that cat nails are not as robust as sga suggested and that trimming them does not impair their usability. sga provided several sources suggesting that indoor cats often engage in predatory behavior outdoors, despite being fed at home. SupremeDonut responded that the sources sga provided referred to free-range and feral cats, rather than indoor house cats. sga provided additional sources to support the claim that indoor cats also engage in predatory behavior outdoors. sga also mentioned the hypothesis that some amount of injuries or exposure to allergens can be beneficial for children’s immune systems, and provided a source to support this claim.

Lately SciAm has been running and re-running an article on social media, focusing on plastic cooking utensils, storage etc. as sources of microplastic accumulation in humans.

I'm not disputing that plastics in food prep do contribute to microplastic bio-accumulation - my question is, are these actually dominant sources?

Comparative numbers haven't risen to the forefront of my web searching.

If say 75% of our microplastic uptake is via water and food that was already contaminated (by landfill seepage and wind-borne urban dust) before it entered our homes, then telling consumers to replace all their plastic spatulas and storageware with wood, glass and metal ... is just Big Plastic shuffling off responsibility onto consumers, just like it did with the lie of plastics recycling.

https://phys.org/news/2025-03-dark-energy-rattling-view-universe.html

Hello, I'm not sure if this is the best place to post something like this, but here we go. The above link is of new findings from DESI (the Dark Energy Spectroscopic Instrument) that's been written about by a handful of news outlets this week, and the TL;DR is that the expansion of the universe might not be as consistent as previously thought.

My question is: Could it be possible for the overall universe to only look like it's expanding because the expansion is currently happening within our visible universe? And that in other portions of the universe, far outside of our visible universe, it might be stationary, or even contracting?

To put it another way, could it be possible that the universe as a whole is rippling or oscillating, maybe due to the effects of the big bang, and that our visible universe is such a tiny spec, that from our perspective it only appears that the entire universe is expanding?

I've watched a number of talks where astrophysicists have said that the big bang didn't start from a single point and expand outward like it's usually depicted, but that it happened everywhere all at once. So, from my limited understanding, it doesn't seem like that would contradict what we see from the cosmic microwave background (CMB).

Am I way off base here? Or is this one of those questions that simply can't be currently answered?

Thanks in advance.

Hi, I was wondering if polyphasic sleep is dangerous? What kinds of long term health effects could it have? Did anyone try it?

Hi scientists of lemmy, I'm a computer scientist with basic college level physics and an interest in physics.

I was reading Cosmos by Carl Sagan yesterday and he mentions that if you use a Geiger counter next to an uranium ingot you will detect the uranium's spontaneous decay as a stream of helium nucleei.

Does helium nucleei mean 2 protons and some number of neutrons? What happened to the respective electrons? Does this mean that each uranium atom, with 92 protons, entirely splits into 46 helium nucleei or does it release some number of helium nucleei leaving another element behind? How does the concept of half life play into this? Does it mean that in a uranium half life, half of my ingot would've become helium? Finally, how is this stream of helium nucleei so dangerous to living beings?

Thanks for your attention

Wolfram alpha has a sunburn calculator:

https://www.wolframalpha.com/input?i=time+to+sunburn

I'm out in the sun much longer then the calculator suggests, but I dont get burned.

How do scientists predict the future climate? Do they just calculate the current trends of temperature growth and take the causes of it into account? Or is there some other way. Is it basically some model y = a1*x1 + a2*x2 + ... or something more complex?

You can look at certain structures in one animal and show how they're made from repurposed parts of an earlier animal (like fish gills becoming human ears). Can that be done with humans and those animals with Xenomorph double-mouths? Can you say "in humans, this particular piece of tendon in the neck is what eels reused for an additional mouth" or something along those lines?

Thanks for your time!

If the answer is YES, a related follow-up question: if each visible color of the spectrum were to measure a centimeter in width, how far would I have to move the sensor from the red to detect the change from infrared to microwave, then to radio?

In the knowledge that Sir William Herschel discovered infrared by repeating Newton's experiment, but with a thermometer to measure the temperature of each component of the spectrum, and after placing the thermometer a bit to the side of the red light, in darkness, noticed quite by accident that the device would still register heat, therefore an invisible yet very real component of light was there, warming the thermometer.

Energy in physics feels analogous to money in economics. Is a manmade medium of exchange used for convenience. It is the exchange medium between measureable physical states/things.

Is energy is real in the same way money is? An incredibly useful accounting trick that is used so frequently it feels fundamental, but really it's just a mathmatical convenience?

Small aside: From this perspective 'conservatipn of energy' is a redundant statement. Of course energy must be conserved or else the equations are wrong. The definition of energy is it's conservation.

Now I'm just being the curious layman here, but a Google/YouTube search proved fruitless.

I keep seeing commercials for Gross Pointe Garden Society it made me wonder.

Cells divide and make new cells, is all life on Earth rooted in one super ancestor cell? Or are there parallel paths to cell creation?

Since I haven't found a sub for sociology I decided to post this question here looking for a scientific answer. I'm looking for a more empirical answer rather than opinion based since I think this is critical in understanding such a complex and nuanced topic.

So I noticed that in the USA people are often strongly divided based on whether they identify as being "black" or "white". Basically many people there make this a big part about their identity and separate communities based on it to the point where they developed different cultures and even different ways of talking and behavior solely based on whether they identify as "black" or "white".

As far as I understand it's based on the brightness of their skin color because of slavery but it's not quite clear to me who is considered "black" or "white" since I've seen many people who for example have very bright skin and seem to have almost no African ethnicity but they still identify and talk/behave as "being black".

I wonder why they still have this culture and separation since segregation ended in 1964.

Because in other regions like South America such as Brazil for example this culture doesn't seem to exist that much and people just identify as people and they talk, behave and connect the exact same way no matter the skin brightness. People such in South America seem way more mixed and seem to not have this type of separation like in the USA based on external features like skin, hair or eye color.

To me it kind of feels like this is a political and economic reason in the US that they purposefully want to divide people for their gains. Because the extent to which this seems to have been normalized in Americas every day conversation both in private and in public/commercial spaces feels like brainwashing. And I wonder if this will ever improve since it seems to go as far as people being proud about these racist stereotypes and think this is completely normal. But considering the broader global context and America's historical background it doesn't seem normal. Especially with America's context of slavery you would expect there to be strong efforts of fighting these stereotypes and having a political leadership that doesn't see "color" and only judges based on an individual's personality.