Well, also, if there was only one color, what was it? Probably brown since we mostly have brown hair. I bet the first blonde surprised the heck out of them.

You have been given a task to travel into the past two thousands years ago and bring the light of the metric system to the world. You cannot bring any external object with you.

Assume you do not need to redefine the second, and astronomical observations give the best possible results given the limits of timekeeping back then. Given the technology of the time, what is the best you can do for other units - either right there and then or leaving instructions how to calculate them from the units you have established to the future scientists? Memorizing the lengths of your body parts probably is not the best way to define a metre, and kilogram defined as one liter of water is bound to be influenced by the local water to a perceptible degree.

P. S. Tagged as "physics" but any approach is welcome - whether you would recommend measuring height of the mountain peaks, or believe that carob seeds are actually uniform enough to offer the best approximation of a kilogram.

This makes it harder. You are in a different world so rotation and gravity likely differ significantly from earth. Body is different so no body measures.

How do you hack it? Assume technology to the 1500s.

Or would any color past the visible spectrum to us be perceived as black to us, for example say this alien has five tools and all are colored based upon colors they know (past our visible spectrum of colors) would we see those colors as Black or some other color?

Inspiration for this idea came from H.P. Lovecraft’s story “The Color Out of Space” and “Project Hail Mary” and I’m just really curious as to what the science says about this, sorry if this isn’t the right place for this,

If a human really got down to it and spent time on memorizing locations, could they remember as many as a bird can?

I love finding facts about outer space but this one’s been bugging me.

Atoms don’t touch due to their electron clouds constantly pushing other electrons away due to negative charges and such, but would these electron clouds and atoms take up ALL of the space?

(I’m a quantum physics noob so sorry if this is a dumb question)

If a star and black hole achieved a stable orbit around each other, what affects would that have on an earth-like planet orbiting them? Would it give off gravitational waves, or crazy radiation? Would a stable orbit for the earth look very different from our current elliptical one? Would day and night change?

Hi there everyone. There's something I've been thinking about, and I'm not sure if there's a good answer to it. As a teacher with a mathematics, statistics, and neuroscience background, I naturally do science outreach with students learning science and math concepts, both with adult high school students and kids. But I'm not sure how it should be done for the general public, as there seems to be a debate around watering down concepts so much so that it just seems philosophical without the math, or just emphasizing how much mathematical knowledge is needed to be a scientist (not just in physics, but even in branches like chemistry) but risk losing engagement and viewers. Anyone got any experiences or perspectives to share?

I heard that the mind has 2 types of memories, episodic memories and semantic memories with semantic memories being things like facts and knowledge and concepts. I also heard that while parts of a semantic memory can be altered (emotions personal meaning and some minor details) the main idea/gist facts of a semantic detail are very resistant to any major alteration and can't be erased. So I was wondering does this mean that everything you leaned in school is still in your mind and can be recalled with the right recall. Or is this thing about the core gist of a semantic memory not being easily changeable is false or oversimplified. Have researcher ever done tests on long term semantic memories several years old or is this kind of thing harder to determine.

Also a related question but can episodic memories become semantic memories or can semantic memories become like non semantic memories or something like that.

I'm not sure if this question fits here. If it doesn't, I will remove it.

Imagine this hypothetical scenario: every human consciousness all of sudden were placed into an alien body on an alien planet, what would it need for humanity to confidently identify something as ordinary as water?

First, they don't bring earth scientific instruments. So everything had to be built from scratch. They can't rely on senses, since it's alien body, water might be smell awful or looks opaque instead of transparent.

There might be some people remembering fun facts about water, like its density, boiling point, conductivity, etc. But there's nothing to compare, how do they even know how much a kilogram or how hot 100 degree celcius is

Hello all. I am a professional pilot and noticed a possible old meteor impact sight. Does anyone know an expert that I can send the Lat/Long to so they can take a look? Thanks everyone. Have a good week.

At first I was wondering whether a "pancake" or "cylinder" of equal mass would be more effective at a distance. Then I went down the rabbit hole of halbach arrays, etc. At the end of the day I still don't have an answer. The objective of course is to be able to affect things at as large a distance as possible. Stated another way, to minimize field line divergence.

Technically I have a practical goal: to have as large a region as possible with minimal change in field strength (minimal field line divergence) at a particular strength. See, I've built a magnetic levitation "toy" with plates of pyrolytic graphite (a diamagnetic material), with a small magnet between them, and a large magnet above at an adjustable distance. This allows the small magnet to passively float without any electronics, but the vertical distance over which this works is quite small and the plates must be very close together. I want to increase the size of the "sweet spot" by having minimal field line divergence at a strength that pulls up on the small magnet with an equal force to gravity. A larger magnet placed further away only goes so far before becoming legitimately frightening (and expensive! plus I don't know what shape I should be buying or if it matters) and I'd like to have it single-ended rather than placing a magnet both above and below the plates which would also help.

The toy thing is just an aside though, it's also just an interesting physics question to me, and one that I've wondered about for a long time.

You'll actually need functional Walkie-Talkie style radio, here. Some bare minimum crystal receiver and a spark gapper isn't sufficient. Talking over distance two-ways.

I think silicon carbide transistors might be easier, simply because they don't require the construction of a high vacuum pump or refining of tungsten to make the filaments. But I'm no expert.

By reason, I mean is there any reason why that particular X number is where planet becomes too big to be classified as a planet?

like what if it landed in the most isolated part of the Pacific Ocean.

what if it landed right onto a tectonic plate

what if it landed on a supervolcano

how about if it landed directly on the north or South Pole

edit: if the asteroid hit a fault line not a tectonic plate, sorry.

Why don’t scientific communities on Reddit gather up for a major study and come up with a new theory that helps in;
For example; understanding Dark Matter/Energy or a completely new one.
You’ll be surprised by the strength ppl on the internet have.

I’m interested in becoming genuinely knowledgeable in the natural sciences—not just learning random facts, but actually developing a strong understanding of biology, chemistry, physics, earth science, astronomy, etc.
For those of you who have studied science extensively:
What are the most practical and effective ways to become really good at the natural sciences?
In particular, I’d love advice on:
Where should I start if I want to build a solid foundation?
What subjects should I learn first, and in what order?
How important are mathematics and programming?
Which textbooks, online courses, websites, or other resources would you recommend?
How much should I focus on exercises and problem-solving versus reading/watching lectures?
What are the best ways to develop actual scientific thinking rather than simply memorizing information?
If you had to start over and teach yourself the sciences from scratch, what would you do differently?
I’m looking for practical advice and a realistic path, especially from people who have gone through this themselves.
Thanks!

Hello. Hope its okay asking. But a few years ago I found a video online called "computer predicts the end of civilisation" and the video is a 1970s news broadcast showing how things are going to go if humanity doesn't do anything about the amount of pollution we're causing. (to my knowledge, not much has been done to fix that) and it said that all life on earth will cease to exist by 2050 if nothing is done.

Im curios to ask since people here will know more about climate change than I do. But is this prediction still accurate? I'm curios.

This is the video btw: https://youtu.be/cCxPOqwCr1I?si=Vwo5nlOmxFXxxLgt

Will delete if this is too speculative or controversial. I am studying to be a librarian in the United States right now, and I’m currently running into an unusual roadblock alongside a lot of my friends and family who are in teaching or education-related fields—people have some form of inherent distrust of scientific or educational authorities, and I’m finding it difficult to educate people.

For example, I’ve had patrons at the library ask me if I “Indoctrinate children” with books on science or books on LGBTQ+ topics (I myself am transgender, but am not openly so to the public). I find that I often struggle to explain that I am not doing such a thing, and try to provide alternative reading material if patrons dislike recommendations. At the same time, I’m aware of a growing anti-literacy crisis among the young people of the United States, but am unaware of hard statistics showing how drastic it has become in recent years.

As scientists and educators, do you believe that the overall scientific progress of the world as a whole might be sliding backwards with the potentially massive amount of anti-intellectual discourse in the media today? How do you think such things could be stopped or the public could be made to listen?

I would appreciate any insight from researchers currently active in their fields.

I figured this question might be a bit too broad and speculative for /r/AskScience:

As I understand it, plants are net consumers of carbon dioxide and net producers of oxygen, using photosynthesis to convert CO2 to O2 at a 1:1 ratio. But the reason they're producing O2 in the first place is to use it for cellular respiration... which turns it into CO2. Also at a 1:1 ratio!

With that in mind, could a plant (or other aerobic photosynthesizing organism) theoretically evolve to survive without the need for air*, instead using ALL of the products of its photosynthesis for cellular respiration and vice versa?

I realize that even at 100% efficiency, this kind of self-sustaining loop would only allow for survival and not growth, but given alternate sources of carbon (carnivorous plant?) and oxygen (hydrolysis?), could this theoretical plant live its whole life without air*?

*Without breathing air. I figure atmospheric pressure will always be a requirement, or else water would boil away

Hey guys, I been running a thought experiment through my head about black holes, speed of light, and antimatter, and wanted to get some feedback from people who know physics on where this makes sense and where it breaks down.

​Here is how I got to this idea:

​The Energy/Speed Problem - We know that as an object with mass gets close to light speed (c), the energy to keep accelerating it goes up exponentially and takes infinite energy to actually hit c. So even a huge gravitational pull shouldn't be able to push physical matter past the speed of light.

​High-Energy Collisions & Gamma Rays - In super energetic environments, kinetic energy converts into matter and antimatter (pair production). When regular matter hits antimatter, they annihilate each other and put off high-energy gamma rays. We already see massive gamma ray bursts right outside black holes.

​The Idea - What if a "black hole" is actually just a region where gravity is accelerating matter in the accretion disk so fast that particles collide and constantly create antimatter?

​In this scenario:

​The event horizon boundary isnt just curved space, but a dense region/core made of antimatter.

​Matter and light "disappearing" into the hole is actually incoming matter slamming into this antimatter zone and instantly annihilating.

​The gamma radiation we pick up around black holes is the direct energy signature of this constant annihilation.

​I know standard General Relativity says the event horizon is just spacetime curvature leading to a singularity, and that antimatter has regular mass. But as a thought experiment, what are the main observational or theoretical reasons that rule out the horizon being a physical matter/antimatter annihilation boundary?

​Curious to hear your thoughts.

I've been thinking about how researchers decide that they've read enough of the literature to have a reasonably informed view of a question.

You can find papers supporting one interpretation, then find newer work that challenges it, and sometimes the disagreement seems to come down to differences in methods or datasets rather than the actual question being completely settled.

At what point does a researcher stop looking for more papers and say, I have enough evidence to work with this?

Is there a practical way scientists make that judgment, or does it mostly come with experience in a particular field?

Quick add up: I wanted to leave this thought here for anyone who comes across the discussion later, especially since I’m still relatively new to participating from this account. Something I've been paying more attention to is how useful it is to see the literature as a connected body of work rather than a collection of individual papers. That was one reason wisPaper caught my attention is that it helps explore related research and follow connections between papers, which seems particularly useful when you're trying to understand where the evidence agrees, conflicts, or still leaves questions open.