Could it be possible for multiple (2 or more) Super Continents to exist on one planet? How big would a planet have to be to be able to hold multiple of such large landmass?

Polytetrafluoroethylene is used in myriad products from dental floss to lubricant, and it is a fluoropolymer that can be manufactured from perfluorooctanoic acid—a known carcinogen.

Why and how is polytetrafluoroethylene safe for human use and consumption?

I understand that scientists can use methods like spectroscopy to learn what's on a planet atmosphere or in its surface. But the other day I saw a diagram of Mercury's inner core, which I found quite fascinating. How do astronomers even know something like that?

What is the precise reason that cells lose their ability to regenerate over time? And which genes primarily control the process of cellular regeneration? Are these genes present in each cell individually? If so, why do cells in the body not vary in their regenerative capacity with age according to the nature of each cell and the conditions it is exposed to? In fact, we observe that cells age at nearly the same rate, with little variation between them in this regard. Or is it that the genes driving aging in different cells of the body act synchronously and share the same nature, which is why we see a simultaneous aging process across cells? Alternatively, is cellular regeneration directed by a central mechanism that guides all body cells toward this process? If so, where is this central system located? Is it in the brain, or is it in another organ?

Imagine you take a really deep breath and exhale all the air from your lungs. Then, you are relaxing and only take casual breaths. Is the old air still in your lungs?

I feel like this is a dumb question, but I genuinely want to know. How do scientists find out how many organisms or just tiny things in large quantities in general are there? If you look up “how many organisms are in the human body?” It’ll say 39 trillion. If you look up “why do cats have a good sense of smell?” It’ll tell you they have 200 million olfactory receptors.

How did they count that? How did they round it to that? I’ve asked google this questions in multiple different ways but I don’t get the exact answer. I’m sorry if this seems like a dumb question ! I hope it doesn’t.

This might be slightly political, I live in Iran and as you might've heard Iran's been claiming to "develop their nuclear program" for a few years now

From what I've seen/heard, nuclear weapons use the depleted resources of a nuclear reactor which is supposed to produce insane amounts of power, but meanwhile Iran is really struggling with their power production and there seems to be no trace of any nuclear power production anywhere (Could be wrong)

Now ofc a lot of stuff could be happening that we don't know but my question basically is: Is it possible to efficiently develop nuclear weapons without going after nuclear reactors? Does it make sense in terms of economics? Because we've at least been expecting the energy crisis to end after this whole nuclear deal

For example, what would hurricanes have been like when all the land was congregated into Pangea? Would they just raged across the ocean uninhibited by any land masses? Would dinosaurs and giant arthropods have experienced tornadoes? And how strong would these natural disasters have been compared to modern times?

I mean if we follow the evolution theory, we all evolved from the same ancestors.

Is that partly why genetic defects can still happen at smaller risk even if the offspring in question was not made between two closely related (by blood) individuals?

Side question: Does the entire asteroid belt have the same orbital year, or is it different for smaller asteroids versus bigger asteroids?

This is probably a kind of dumb question, and i’ve kind of seen it answered before, but wanted more clarity. I have always wondered how we know radiometric dating and other methods like carbon dating to be accurate? I have already read answers such as it follows a “rate of decay” and it’s like a “clock that was fully wound up at the start, but has now run down half way. If you watch how much time it takes per turn and how many turns the spring can take, you can figure out how long ago it was fully wound.” But I don’t find this answer very sufficient (i could be dumb). How do we know the rate of decay follows a particular pattern? How do we know it decays linearly or exponentially or in any set way at all if we have not observed the entire decaying process of the elements we are tracing? (or even a fraction of it since isotopes like uranium-235 have a half-life of 700 million years). In other words, is it possible that our dating methods could be completely wrong since we evidently assume a set pattern for decay? Are we just giving a guess? I am probably missing something huge, and I am incredibly ignorant in this topic, but i’ve just had that question nagging me recently and am looking for an answer.

Dingoes have been in Australia for over 4000 years and have embedded themselves into the ecosystem playing the important role of predator. Additionally, horses evolved in North America and went extinct over 11000 years ago and were re introduced by Europeans a few centuries ago.

Unsure what I should tag this as.

We know that animals can suffer from depression for example due to abuse or other reasons. Are there autistic dogs or schizophrenic cats out there, or are some disorders human specific?

So Chernobyl was spreading nuclear radiation (like it was dust or smoke) before it was contained.

But what's stopping a filtering process to capture those toxic fumes? Can radiation be captured?

Could the elephants foot just be continually filtered air around it?

Is it because the rotation of the outer core is influenced by Earth's rotation? Is is physically dragged around by the rotation of the upper layers?

If they are Chemically the same how can a machine tell the difference?

Hello, I was genuinely curious about this because it seems a little confusing to me. One problem in militaries using radar, specifically Air-to-Air defenses and aircraft, is that things like the ground, trees, mountains, and clouds or adverse weather can interfere with the radar, so they have to try to filter it out.

Meanwhile Radio Telescopes used for astronomy seem to not have a problem working under bad weather and even rain.

Is it a difference between frequencies of how the two are used or is there some other at play here?

I've tried searching around and others asking similar questions of aging whiskey in barrels, but all the answers only talk about the flavors added by the aging process. What is happening at the molecular level that changes clear liquor brown? Wine does not impart color from oak and neither does beer, but a fortified wine can change color. Does it have to do with the percentage of alcohol or viscosity, or something else?

We are scientists with the Center for Western Weather and Water Extremes (CW3E) at UC San Diego's Scripps Institution of Oceanography. CW3E provides innovative water cycle science, technology and outreach to support effective policies and practices that address the impacts of extreme weather and water events on the environment, people and the economy of western North America.

Our work studying atmospheric rivers is instrumental in supporting water management decisions and flood forecasting. But what exactly is an atmospheric river? Great question. They're massive ribbons of water vapor in the sky that can deliver large amounts of precipitation (rain and snowfall). Accurate forecasts of these phenomena are essential to both water managers and public safety officials.

You can visit our website to dive deeper into our forecast tools, read our latest AR outlooks and storm summaries and learn more about how our tools can be used.

One of the atmospheric river forecasting products CW3E created with partners is the atmospheric river scale (AR Scale). You can sign up to receive AR scale alerts when ARs are forecast along the US West Coast.

The team will be starting around 9 AM PT. Ask us anything!

List of participants:

• Sam Bartlett - Researcher & Meteorologist
• Chris Castellano - Meteorology Research Analyst
• Julie Kalansky - Deputy Director of CW3E
• Shawn Roj - Forecast Verification Analyst

Username: /u/CW3E_Scripps

I have been a weather fanatic for about as long as I can remember. For around 20 years I've been reading weather models and analyses. However, when trying to understand what caused the weather phenomenon in Spain recently, I can't really get my head around it.

The general explanation that I'm reading is "The rains came from a high-altitude low-pressure weather system that became isolated from the jet stream, according to AEMET. These storm systems are known locally by the Spanish acronym DANA or more generally as cut-off lows.".

Ok, clear. But why does this had such a dramatic effect? What makes cut-off lows so intense? " A closed upper-level low which has become completely displaced (cut off) from basic westerly current, and moves independently of that current. Cutoff lows may remain nearly stationary for days, or on occasion may move westward opposite to the prevailing flow aloft (i.e., retrogression).".

As far as I am aware, this is not a uncommon occurrence in Europe. Can someone maybe dumb this down for me? Or maybe have a synopsis about the situation?

I have no official meteorological education or background. However my theory is that this low was stationary, unreasonably cold and drew in tons of moisture because the balearic sea was still so warm(?). This caused all this moisture to condense in a short amount of time in the same place(?).

Can someone dumb this down for me?

I was reading that the Jovian moon of Europa has potentially 40-100kms of liquid water under its 10-15km ice crust, and I was wondering; assuming you could magically get through the ice, how would the pressure work? Europa's smaller than Earth, so the water would weigh less, but also you could go a lot deeper - as the deepest part of Earth's oceans is only 11km. Could we use a 21st century submarine on Europa, if it somehow got teleported there?

i've already spent a few hours looking up probably the wrong things and i'm already tired. are there any special effects that make the trajectory of light deviate from the normal conic sections in classical physics, specifically in extreme gravity such as near black holes?

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Physics, Astronomy, Earth and Planetary Science

Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...".

Asking Questions:

Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists.

Answering Questions:

Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience.

If you would like to become a member of the AskScience panel, please refer to the information provided here.

Past AskAnythingWednesday posts can be found here. Ask away!