If some elements have such a short half-life, why are they still here? |
- If some elements have such a short half-life, why are they still here?
- Chemistry - is it at all possible of accurately predicting properties of compounds?
- how do things exposed to radiation become radioactive?
- How could we get energy out of a fusion reactor?
- How exactly does soap wash you hands?
- What happens when you take a picture of a computer screen?
- How are the names of certain stars, galaxies, or other celestial objects given?
- Why are clouds white?
- Out of all alkali metals, why is it that Lithium used in batteries? What makes it supperior to use over other alkali metals which have properties alike.
- What are the sources of space radiation?
- My understanding is that a magnetic field only exerts a force on a charged particle when the particle moves. Why do bar magnets pull each other when held so that neither is moving?
- Does laminar flow occur more easily in a fluid with a higher viscosity?
- If Bees were not widely populated in the Americas until 1622, how did the flora survive?
- Could someone answer this question I have regarding telomeres?
- Where does dust come from?
- Approximately how many animals in total are found in the fossil record, i.e., the total number of actual animals not the number of species?
- Why is Hubble time the upper bound for the age of the universe?
- What happens to fields as they approach and reach the speed if light?
- Why does poor circulation cause swelling/edema?
- Where does our immune system store information about certain pathogens?
| If some elements have such a short half-life, why are they still here? Posted: 19 May 2019 09:26 PM PDT I'm not understanding something about radioactive decay, for example astatine has a half-life of between 5 and 10 hours depending on the specific isotope, yet it's naturally occurring. Why isn't all the Astatine in the world decayed into nothing? [link] [comments]  |
| Chemistry - is it at all possible of accurately predicting properties of compounds? Posted: 19 May 2019 10:10 PM PDT in my first chemistry class I asked the teacher "would the melting point of an alloy be the weighted average of its component elements?" and the answer was "no". is it absolutely impossible to calculate melting point, boiling point, density, conductivity, etc... without experimentation? what are the factors that change the properties of compound drastically from their components? [link] [comments]  |
| how do things exposed to radiation become radioactive? Posted: 19 May 2019 05:09 PM PDT Google just shows results for what radiation is, and why certain elements are radioactive. but apparently radiation can 'infect' normally non-radioactive things. How does that work? [link] [comments]  |
| How could we get energy out of a fusion reactor? Posted: 19 May 2019 08:40 PM PDT In something like a tokamak, the very high temperatures produced by the fusion reaction are kept carefully isolated from the walls of the device with magnetic fields. If we get to the point that we can use fusion to create electricity, how would we actually get that energy out? Presumably we need some sort of heat exchange medium and a way to get that into and out of the reactor - but I can't wrap my head around how that could work. It seems like anything that could interact with the plasma should be destroyed and/or break the containment and wreck the reaction. [link] [comments]  |
| How exactly does soap wash you hands? Posted: 19 May 2019 08:12 PM PDT |
| What happens when you take a picture of a computer screen? Posted: 19 May 2019 09:03 AM PDT Can anyone tell me how come, when you take a photo of a screen with your phone, the image is covered in waves that you can't see with the naked eye on the computer screen? [link] [comments]  |
| How are the names of certain stars, galaxies, or other celestial objects given? Posted: 19 May 2019 09:19 PM PDT I mean, some of these galaxies have weird names like NGC5128, ULAS J1342 + 0928, 3C48, and other odd combinations of numbers and letters. I understand that this is probably based off a classification system, but what do these names actually mean/represent? How is a galaxy (or any other celestial object) given a name? [link] [comments]  |
| Posted: 19 May 2019 09:58 AM PDT |
| Posted: 19 May 2019 07:58 AM PDT As the title says. I am trying to understand, but I can't find anything on the internet. I'd really appreciate if someone who knows the answer would explain to me. Lithium is supposedly the least reactive out of all the alkali metals. It has one valence electron, which is willing to release to another atom. But so are all of the other alkali metals. They all have one valence electron. I don't know why or even if lithium has any advantages over other alkali metals. If yes, what are they? Please help me out reddit! Have a good one [link] [comments]  |
| What are the sources of space radiation? Posted: 19 May 2019 11:33 AM PDT As far as I know one of the biggest problem for manned flights and communication satellites are space radiation. But what are the sources of it? [link] [comments]  |
| Posted: 19 May 2019 03:22 PM PDT I took a class and learned that the force on a charged particle moving through a magnetic field is: or the cross product of (charge * velocity) and the Magnetic Field. I don't understand why, then, if two magnets that are held so that they don't move relative to each other feel a push/pull. (or a magnet and any ferromagnetic object) [link] [comments]  |
| Does laminar flow occur more easily in a fluid with a higher viscosity? Posted: 19 May 2019 03:58 AM PDT |
| If Bees were not widely populated in the Americas until 1622, how did the flora survive? Posted: 19 May 2019 10:19 AM PDT |
| Could someone answer this question I have regarding telomeres? Posted: 19 May 2019 02:04 AM PDT Question Since cellular replication (one cell dividing into two which divide into four and so on) and gametogenesis at least both start out with cell division and this has been shown to generally decrease telomere length how do we continue to trend towards a longer lifespan? Extra information regarding why I ask The way I understand it is that even in the most healthy person most cells eventually have such short telomeres that the chromosomes stick together and the cells are no longer able to replicate. Cancer cells and certain hormones that promote telomere growth can slow down this telomere shortening and even make telomeres grow longer but generally by the time a human undergoes puberty there have been trillions of cell divisions even in a single organism not counting all of the cells in our evolutionary history and based on this trend, at least in humans you'd expect a trend towards extinction unless there is some mechanism in gametogenesis or a process related to it that would increase telomere length significantly enough that generation after generation people continue to exist basically. I've tried looking into this with little to no avail so could someone explain this process for me better? Is there some biological process that sets the telomere length or adds a certain amount to them during gametogenesis or embryonic development that gets shut off at a certain point or is there something I'm not considering here if it all just sounds like descendents of people who are 25 years old will have significantly less chance of living a longer life if we just consider telomere related aging than someone born to 16 year old parents? Obviously I'm not promoting childhood pregnancy or anything but I'm genuinely curious about this - modern humans have existed for between 350,000 and 70,000 years (depending on if we go with anatomically modern or behaviorally modern) and they're the result of a process of more than 3.5 billion years of evolution representing more than 7 trillion ancestors if we account for single celled precursors (though some were prokaryotic lacking telomeres and having a single chromosome). Somehow we continue to have adequate telomeres for the most part until we get old or get some telomere related disease. At significantly old ages children are less likely to develop properly but this usually isn't a problem for parents between 20 and 35 years of age. There's a lot of telomere shortening in that time and while there are ways telomeres do grow longer I haven't really found the adequate explanation for our continued existence simply based on the problems associated with cell division and telomere shortening and how we overcome this with cell division leading to gametogenesis or if telomeres grow longer earlier in life and shrink after a certain point. If anyone could explain this in detail that would be appreciated - even a simple answer would help but a detailed one down to the biochemistry on the molecular or quantum level would be preferred. If nobody knows that would be okay as well so that perhaps this will give us something more as a species to investigate. Note: I saw something in another post about stem cells having a large amount of telomerase in them but also drugs that increase telomere length in other cells might lead to cancer. Is it really as simple as stem cells that answer the basics of what I'm asking or is it something more I may have overlooked? [link] [comments]  |
| Posted: 19 May 2019 09:04 AM PDT Why does dust exist? Where does it come from? What is it made from? [link] [comments]  |
| Posted: 18 May 2019 11:01 PM PDT |
| Why is Hubble time the upper bound for the age of the universe? Posted: 18 May 2019 11:00 PM PDT Isn't this proposition based on the idea that expansion rate of the universe is slowing down? After the de-acceleration parameter was found to be negative, doesn't that imply the universe would be older than 14 billion years? [link] [comments]  |
| What happens to fields as they approach and reach the speed if light? Posted: 18 May 2019 08:44 PM PDT I am curious what physically happens to a field as it approaches and then hits the speed of light. Like say a magnetic field, does it change? Or electromagnetic? Or are there any fields that behave strangely as they speed up and hit C? I asked this question once in a FB group and got a smartass remark about "Maxwell's equation tells you, duh." Sadly, I am not well versed enough in math or physics to be able to understand his equations and what they mean "in the real world." I'm not exactly a layperson, but I am by no means well-versed. [link] [comments]  |
| Why does poor circulation cause swelling/edema? Posted: 18 May 2019 06:29 PM PDT |
| Where does our immune system store information about certain pathogens? Posted: 18 May 2019 04:47 PM PDT If a person is infect with a disease the immune system can save information about the pathogen, so that it can be fought off more easily the next time the person infected with that disease. This also helps our immune system build a stronger protection against a certain type of pathogen. Where does the immune system store this information, what and how is it "read" and "evaluated"? [link] [comments]  |
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