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Monday, October 25, 2021

How do we actually know the number of protons in a nucleus/atomic numbers?

How do we actually know the number of protons in a nucleus/atomic numbers?

How do we actually know the number of protons in a nucleus/atomic numbers?

Posted: 24 Oct 2021 08:24 PM PDT

I'm just curious as to the method by which atomic numbers for each element were discovered. We obviously don't have microscopes that can see down to that level, so it's clearly not known by direct visual means, but I've struggled to find a good answer through search engines.

submitted by /u/Aggravating_Judge_31
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What is the meaning when people say “99.99% the speed of light” instead of just speed of light?

Posted: 25 Oct 2021 01:15 AM PDT

I hear this phrase a lot and it doesn't make much sense to me.

Since the speed of light is a big number, I know a lot can change in that last 0.01%, does something else significant happen when that transition is made?

Also I know that in order to accelerate anything with mass to speed c, it would require infinite energy, but to accelerate to 0.9999c would that require finite energy?

submitted by /u/sssinc
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Are there any avian species that haven’t evolved significantly since the Cretaceous mass extinction event?

Posted: 25 Oct 2021 05:39 AM PDT

I know that the cassowary emerged around 60 M.y.a but do you know of any avian species that go back further, preferably pre Chicxulub?

submitted by /u/ReubFrFx
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How long does it typically take for a planet to form?

Posted: 24 Oct 2021 10:13 PM PDT

Are there any jet aircraft that carry their own oxidizer?

Posted: 24 Oct 2021 10:39 PM PDT

I know that during normal operation jet aircraft use air compressors to scavenge oxidizer from the atmosphere, but I'm wondering if there's ever a use case for carrying extra oxidizer on a jet aircraft.

For example, suppose you had a fuel system that could dump more fuel into the combustion chamber than the air compressor could manage, you could add extra oxidizer directly to the combustion maybe for a higher performance boost than would normally be possible with a purely air-breathing engine.

Or for another example, what if an aircraft at very high altitude wasn't able to scavenge enough oxygen to fully generate the thrust it wanted/needed.

submitted by /u/EZ-PEAS
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How Do Engineers Work Around Material Fatigue?

Posted: 24 Oct 2021 11:25 PM PDT

I've yet to see bridges, towers, or roller coasters taken apart to be replaced due to material fatigue, yet I've seen several machines taken apart and parts replaced when fatigue sets in. Even the shop i used to work at had the roof cross members replaced when they became fatigued (granted, these beams were over 100 years old). Even my machine's dies need replaced when you start having them flex more during bending due to fatigue. There doesn't seem to even be much information on fatigue and how it's calculated. So how is all of this stuff figured out, prevented, and compensated for?

If you have any book suggestions on this subject, I'd appreciate the recommendation as well.

submitted by /u/djinbu
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Does an allergic reaction to an ingredient in a vaccine make the vaccine less effective?

Posted: 24 Oct 2021 02:48 PM PDT

The electrostatic deflection of water, and Can a stream of water be deflected by a magnetic field?

Posted: 24 Oct 2021 12:20 PM PDT

A thin stream of water may be deflected or 'bent' by an electrostatic charge, and this can be demonstrated with a charged object such as a comb, and a thin stream from a faucet. Questions:

Would the deflection be larger if de-ionised water was used?

Given that water is affected both by electrostatic charge and by gravity, why is the water apparently not also deflected by a very strong magnetic field, say from a powerful electromagnet or neodymium permanent magnet?

submitted by /u/a-renrael
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How is it possible for a river to dry up completely then go back to normal without a mass extinction level event?

Posted: 24 Oct 2021 08:33 PM PDT

So I was just reading up on some doomsday news and came across an article regarding the salmon stock in the Yukon River collapsing.

I went and did some digging and came across another article saying it dried up within 4 days after glaciers retreated back in 2017. If thats the case shouldn't everything have died off?

Also how did the river return to normal if the glaciers haven't magically gained new ice?

I find this kind of stuff unfortunate but fascinating - any info is appreciated!

submitted by /u/bermudaliving
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Why are congenital brain deformities(i.e. Alobar Holoprosencephaly, Anencephaly, Syncephalus) so deadly and if physically possible can current medical technology keep these children alive beyond a few hours?

Posted: 24 Oct 2021 08:01 PM PDT

With Covid-19 boosters rolling out, are we seeing a drop in antibody titres in the months after the third shot just as we did after the second?

Posted: 24 Oct 2021 05:35 AM PDT

I keep reading that we might find the boosters fade and that we could need to do them regularly etc - but there's little out there about how they are actually performing. Have meaningful patterns cropped up in the data, or is it too early to tell?

submitted by /u/bnndforfatantagonism
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If tectonic plate elevation causes mountains to form, why are there valleys between mountain ranges?

Posted: 24 Oct 2021 10:26 AM PDT

I.e. why is it not a continuous line or 'spine' of mountain peaks? Is it because the tectonic plates are shattered beneath so collision causes more than one pieces to be elevated? Or is it that after they've formed a mountain, they move on and make another one a mile away, like a blunt knife pressing on dough?

submitted by /u/nickoskal024
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Lots of products claim to "boost" or "speed up" your metabolism. Is that actually a thing that can be done, and if so, what's the science behind it?

Posted: 23 Oct 2021 04:11 PM PDT

What is the general effect of exposing a plant to continuous illumination?

Posted: 23 Oct 2021 06:30 PM PDT

I've seen some mixed results- some implying negative, some positive on the effect of constant light exposure on plants.

Is the effect quite subjective to the species of plant, or can the trend be generalized?

Can plants get "stressed" like animals do under constant light exposure-in a plant's physiological manner of stress, ofc.

submitted by /u/parkeddingobrains
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What treatment(s) does the US do to its water that makes it safe to drink that other countries don't do?

Posted: 24 Oct 2021 09:55 AM PDT

How does sound travel after breaking the sound barrier?

Posted: 23 Oct 2021 04:03 PM PDT

As the title implies, how does the sound from a super sonic vehicle change after it's broken the barrier? Is there a significant difference in the way the waves travel/how the human ear perceives it? Does it change frequency?

submitted by /u/AndoftheSevenSeas
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Sunday, October 24, 2021

Can the current Covid Vaccines be improved or replaced with different vaccines that last longer?

Can the current Covid Vaccines be improved or replaced with different vaccines that last longer?

Can the current Covid Vaccines be improved or replaced with different vaccines that last longer?

Posted: 24 Oct 2021 05:14 AM PDT

What is the current accepted risk of Covid-19 infection through fomite transmission?

Posted: 24 Oct 2021 02:12 AM PDT

I apologize in advance because I know this has been asked before, but I would just like some clarification if someone is willing to give it. I have read the [CDC update that came out earlier this year which detailed how the virus is spread primarily through respiratory droplets and not surface transmission, which said the chance was around 1 in 10,000 for every infected touch](https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/surface-transmission.html). After doing a little more digging though, I saw that [some of the studies tested outside objects, like traffic light buttons](https://pubs.acs.org/doi/10.1021/acs.estlett.0c00966). I'm wondering then, is the risk really considered that much higher without accounting for environmental factors like wind? The reason I ask is because I work at a grocery store that has basically done away with some of the early Covid safety precautions of last year. I go about my day touching self checkout screens, money, and even produce likely hundreds of times a day. I wash my hands frequently and use hand sanitizer a lot as well, but am I still putting people at risk?

submitted by /u/Quirky_Analysis7336
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Why do slabs of crust submerged into the mantle have lower temperatures than its surroundings?

Posted: 24 Oct 2021 12:04 AM PDT

I was wondering exactly why we have "colder" slabs of rock submerged into the mantle. Creationists state that it is because of the fact that the rock was submerged recently and the time it has been there hasn't been enough to warm it like the rest of the mantle and if it were millions of years it would be warmer now. I remember reading something about the material of the rock being the case and I found something here standing it's the compression of the crust and its materials but I'd like your thoughts

submitted by /u/Hybrid_Momentts
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When will covid-19 vaccines be available for people under 12 years old?

Posted: 24 Oct 2021 05:47 AM PDT

How does glow in the dark stuff work?

Posted: 23 Oct 2021 12:26 PM PDT

As we aproach the spookiest part of the year, people wearing glowing skeleton costumes flock the streets and glowing skulls decorate windows throughout suburbs around the world, my question is: How do ''glow in the dark'' substances absorb UV light yet emit visible light?, Why don't they emit more UV light? & Why do they only emit light when in the dark?

submitted by /u/The_noseless_Ginge
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Why are planets so bright?

Posted: 23 Oct 2021 11:41 AM PDT

According to the inverse square law, light gets dimmer at an exponential rate the further the receiver is from the object, and since they are reflecting light instead of emitting it, I don't understand why something reflecting sunlight from millions of miles away would be so bright, regardless of how large it is.

submitted by /u/burntMYfingersONcat
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What is an amplituhedron and how is it useful?

Posted: 23 Oct 2021 11:12 AM PDT

Why aren't moths of families like Castniidae or Sphingidae considered butterflies?

Posted: 23 Oct 2021 07:14 AM PDT

They have clubbed antennae and are diurnal.
They basically look like butterflies, albeit a bit on the chubby side.
Is there a sensible explanation for that?
Thank you in advance for replies.

submitted by /u/Worekjarzyn
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How much protection does a single dose of the AstraZeneca vaccine provide against Covid-19 in comparison to getting both doses? Why are two doses even required?

Posted: 23 Oct 2021 11:52 PM PDT

Do Light Sails work in the Atmosphere?

Posted: 23 Oct 2021 05:27 AM PDT

I understand they've been designing light sails for a while now to catch the light from the sun in space, but I can't find a single thing about whether or not they work in an atmosphere.

If light Sails don't work in air, do heat sails exist and do they work in the atmosphere?

submitted by /u/AfricanToto
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Why do planets spin?

Posted: 23 Oct 2021 02:54 AM PDT

If copper does not react with water, why does water stored in a copper utensil taste like metal?

Posted: 22 Oct 2021 08:49 PM PDT

If antartica is the most dryest place on earth then why 99% of its land is water?

Posted: 22 Oct 2021 08:06 PM PDT

What would happen to the brightness ranking of stars in the night sky if we could see all wavelengths? Is Sirius still the brightest star in the night sky?

Posted: 22 Oct 2021 04:12 PM PDT

How impactful is a volcanic eruption on greenhouse effect gases?

Posted: 22 Oct 2021 05:08 PM PDT

Cumbre Vieja is spitting lava and smoke for a month now and it got me wondering how impactful it is on our goals on reducing emissions on a global scale. Those events can significantly worsen our global warming situation?

submitted by /u/chagin
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Does hot or cold water boil faster?

Posted: 22 Oct 2021 02:48 PM PDT

Not sure what the right type of science is for this question but yeah title explains it.

I heard that frozen things are best thawed with cold/room temp water because of blah blah blah science stuff.

So does it work the same way with water?

submitted by /u/Cosmic_W0lf
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Saturday, October 23, 2021

The extended warm period during the "boring billion" between 1.8 and 0.8 Gya is proposed to have been the result of atmospheric N2O being 10x higher than it is today. Where did all the N2O during that period come from?

The extended warm period during the "boring billion" between 1.8 and 0.8 Gya is proposed to have been the result of atmospheric N2O being 10x higher than it is today. Where did all the N2O during that period come from?

The extended warm period during the "boring billion" between 1.8 and 0.8 Gya is proposed to have been the result of atmospheric N2O being 10x higher than it is today. Where did all the N2O during that period come from?

Posted: 22 Oct 2021 09:39 AM PDT

During the boring billion global temperatures were about 4 ºC higher than today due to higher concentrations of greenhouse gases. Scientists have ruled out CO2 as the culprit due to the lack of evidence of ocean acidification. Methane has also been ruled out as it is only biogenic and methanogens are unlikely to have produced enough methane. So scientists seem to have settled on N2O as the offending greenhouse gas, with Proterozoic levels proposed to be elevated 10x over modern levels.

Today, most N2O is either anthropogenic or biogenic, with only a small fraction being formed abiotically. If methanogens were unlikely to produce enough methane to significantly affect the climate, how would denitrifiers be able to produce enough N2O? If the elevated levels were abiogenic, why don't those processes continue today?

submitted by /u/ghostoftheuniverse
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Have there been any attempts to build a solid rocket motor that can be throttled or turned off?

Posted: 23 Oct 2021 07:43 AM PDT

It seems like there would be a lot of applications for a small solid rocket motor that can go from ~0% to 100% or possibly greater.

I'm imagining something like a JATO rocket in terms of size and the creative ways it has been implemented.

It could be something simple such as a mechanism to destroy sections of the propellent and spit out the chunks. It couldn't throttle back up and will spike thrust briefly but it still sounds useful.

submitted by /u/Ott621
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Why do some people who've recovered from covid-19 not develop anti-bodies?

Posted: 23 Oct 2021 12:36 AM PDT

My basic understanding of immunity is that the first time you get a virus, your immune system makes anti-bodies, which then neutralise the virus, and the anti-bodies remain in your blood stream afterwards. Then if the virus re-infects you, the anti-bodies are already there, ready to neutralise it again.

But there's a study which shows a third of people who've recovered from covid do not develop anti-bodies. Why/how does this occur?

submitted by /u/Ok_Professional9769
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What is the difference between the original sars cov 2 and its variants?

Posted: 23 Oct 2021 08:22 AM PDT

I'm basically asking about differences in spread/transmition and severity (hospitalization and deaths). Are there any data on that? Im more interested in the Delta Variant, but any data is welcome.

submitted by /u/th4tsmyus3rn4me
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Is there a scientific consensus on optimal learning sessions and study time management?

Posted: 22 Oct 2021 08:17 AM PDT

Hello there,

I've been having a hard time finding data regarding this side of psychology. While I've found actual papers regarding the usefulness of note-taking under the form of mind maps rather than usual note-taking methods, I can't find enough papers regarding focus time.

We hear advices here and there - I've had high school teachers saying "we can't focus more than 1 hour at a time", I've seen the pomodoro (25 minutes of work / 5 minutes of rest + other arbitrary rules) technique, but it doesn't seem to be a strong research field.

I'm mainly using google scholar for my researches, so maybe my method for searching papers isn't as good, which is why I'm asking for some guidance : does science say anything about how we should focus in order to maximise learning and optimize our time?

Thanks!

submitted by /u/Meljin
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Are July and August borns disadvantaged in school and life?

Posted: 22 Oct 2021 11:13 AM PDT

There is research suggesting that children born in July / August struggle more in school, struggle with reading and writing, more likely to drop out, and be diagnosed with ADHD.

Here in England, a child born in September will turn five shortly after the start of term. A child born in July could will be four for the entire school year.

How true is this and is your child doomed if born in July / August? Here is just one article talking about it.

here

Apparently parents are holding their children back a year to offset this problem but is this a good idea? link

submitted by /u/crystalxuk
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What happens EXACTLY at the triple point of a pure substance?

Posted: 22 Oct 2021 09:15 AM PDT

I'm working on a problem for a binary mixture which is equivalent to the triple point of a single-component system, and that is this: What are the relative amounts of each phase EXACTLY at the triple point? Most descriptions you find say something along the lines of "all three phases can exist simultaneously," but "can" implies that they don't always. And if that is just bad wording, how do you calculate how much of each phase is present, i.e., the phase fractions?

I know that both realistically and numerically speaking, this is not a meaningful question as you can never be exactly at any given point. My question is, then, a purely mathematical one, assuming that the equations used to model a system have an exact solution.

At the triple point of a pure substance (or a three-phase point of a binary mixture with one state variable fixed), there are zero degrees of freedom which can be verified using the Gibbs Phase Rule: DOF = C - P + 2

For a pure component, you get DOF = 1 - 3 + 2 = 0, and the binary mixture with one parameter fixed, you get (DOF) - 1 = (2 - 3 + 2) - 1 = (1) - 1 = 0. This means that the thermodynamic state of the system is completely fixed and that all other state variables can (theoretically) be determined from those conditions.

However, in practice, most systems that I'm familiar with which have more than one phase present have at least 1 DOF, and varying that DOF changes your phase fraction(s). For example, a binary mixture with two phases has 2 DOF. Specifying, for example, temperature and avg. composition fixes the system state and allows you to calculate the individual phase compositions and thereafter the phase fractions from a mass balance/lever rule. You can also do the same with a ternary mixture and three phases using two independent equations to calculate the two independent phase fractions (all three sum to 1, so two are independent).

You can't, however, do that here because there is not enough information available to calculate two independent phase fractions. There couldn't possibly be; not with state variables anyway. If you try (and I have), you get infinitely many solutions/a line in the space of the phase fractions.

Plot of mass balances for 3C/3P system (axes are the independent phase fractions).

Plot of the same for 2C/3P.

All this is leading me to one of the following conclusions:

  1. Phase fractions have no meaning at such invariant points.
  2. Under these conditions, phase fractions are path-dependent quantities.

The first of these makes a sort of logical sense to me but doesn't really make physically sense, because this would imply that either phases don't exist (which seems ridiculous) or the whole system is at all three phases simultaneously (equally ridiculous).

The second is more likely in my mind, and I can find some analogues in systems with fewer phases, e. g., a single component at two phases has 1 DOF (e.g. pressure) yet still needs a value for work/enthalpy supplied to determine a phase fraction.

That said, I haven't found any evidence to support this nor have I found any discussion of it online or in the scientific literature. Any thoughts would be greatly appreciated!

submitted by /u/Imagine_Baggins
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Do other force particles have a spectrum like photons?

Posted: 22 Oct 2021 09:04 AM PDT

Photons carry the electro-magnetic force and operate on a spectrum based on their energy, giving us things like heat and x-rays. Do the force particles that carry the other natural forces also behave differently at different energy levels? Is there (or could there be) a spectrum of the nuclear forces, or of gravity?

submitted by /u/docbob84
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How many, and which viruses are the cause of cold? And why is cold more likely to happen in cold environments?

Posted: 22 Oct 2021 12:50 PM PDT

What new, ground-breaking technologies were first used in the creating of the first satellite (Sputnik 1)?

Posted: 22 Oct 2021 08:46 AM PDT

creation* made a typo in the title. Sorry!

What technologies made Sputnik 1 so special?

submitted by /u/Student-Somewhere
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Which oak species are most likely to successfully take during a graft? (Unfamiliar with cladistics)

Posted: 22 Oct 2021 08:10 AM PDT

https://imgur.com/gallery/7W0fZxD

Marked is the species that I want to work with.

I imagine that the oaks between and including Quercus lyrata to Quercus Muehlenbergii would successfully take.

But how far up, and how far down, do you suspect that the trees are similar enough to successfully graft?

submitted by /u/TaxMan_East
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What was on the opposite side of the Earth when Pangea existed?

Posted: 22 Oct 2021 08:01 AM PDT
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Friday, October 22, 2021

How are inactivated vaccines produced?

How are inactivated vaccines produced?

How are inactivated vaccines produced?

Posted: 22 Oct 2021 01:37 AM PDT

Did Theia actually smash into the Earth or is Earth a combination of Theia and some other pre existing body?

Posted: 22 Oct 2021 12:47 AM PDT

The main theory for how the Moon, Luna, formed, is that a Mars-sized protoplanet named Theia collided with another protoplanet, and the ejecta coalesced into the Moon. But not all of Theia could have become the Moon, Mars has the mass of 6.39e23 and the Moon has a mass more than ten times that, and so it must have radically changed the protoplanet too, becoming more than 10% of the thing. Wouldn´t Theia hitting it have actually formed Earth as we know it and we are just a merger of the two?

submitted by /u/Awesomeuser90
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If you catch a cold, is there an easy way to know or guess which virus is causing it?

Posted: 22 Oct 2021 04:26 AM PDT

Assuming reaching absolute zero was possible, how much pressure would H2O at 0K need to be under to be a liquid?

Posted: 21 Oct 2021 09:22 AM PDT

Why can't adenovirus-vectored vaccines be aerosolized so they don't require needles?

Posted: 21 Oct 2021 09:01 PM PDT

Whether through a nasal spray or inhalation, it seems like there would be less vaccine hesitancy if there was a route of administration that didn't require needles.

submitted by /u/AlkaliActivated
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Why do people only have 10 seconds of useful consciousness at high altitudes when most can hold their breath for at least 30 seconds?

Posted: 21 Oct 2021 10:28 PM PDT

On average people are able to hold their breath for 30 seconds, but in the event of rapid decompression at high altitudes (40,000ft) they will become useless after just a few seconds.

Why is this?

submitted by /u/sucction
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Is the conversion efficiency from fuel to electricity better in gas/oil power plants compared to car engine?

Posted: 21 Oct 2021 01:30 PM PDT

Conversation that I had with a friend. With electric/hybrid cars being more common, we talked about why should we switch to electric cars when the electricity needed to power the car would still need to be obtained from gas or oil power plants?

As I type this, I realised that electricity for the cars can also be obtained from renewable energy sources. But the question still stands. Does the amount of energy obtained from burning gas/oil in a power plant have a higher yield than if we were to use the fuel directly in a car.

Also, I saw a reddit post/news that said that a state in the US is banning gas powered lawn mower. The same question but this time the comparison between a gas powered lawn mower and gas/oil power plant.

P.S If there is another post that had already answered this, I would love to read it. Just didn't know how to word it succinctly to search on reddit.

Thanks in advance!

submitted by /u/maniacalboy
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In North America there are often invasive species from Asia, such as The Spotted Lantern Fly. Are there invasive and pesky species from North America on other continents?

Posted: 21 Oct 2021 08:16 AM PDT

Can anyone explain this phenomenon?

Posted: 21 Oct 2021 09:00 PM PDT

This bottle of Croatian rajika keeps opening back up whenever I put the stopper in. I have never seen this before with something that's not carbonated. Genuinely curios if it's yeast or some other sort of gas being released from the fermentation process.

​

Thanks for the help!

submitted by /u/JCiraolo
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What is the physics behind compound bows and compound crossbows?

Posted: 21 Oct 2021 04:25 PM PDT

I get that it uses a pulley system to transfer the force to the arms of the bow, but I can't find anything that goes in depth into the physics behind it (ideally with figures). Does anyone know or have a link to how the actual physics/engineering works? Like with numbers and equations to go along with the explanations and all that jazz

submitted by /u/_ChestHair_
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When determining vaccine efficacy/effectiveness, is there a point made to distinguish the prevention of infection vs prevention of serious illness?

Posted: 21 Oct 2021 10:26 AM PDT

For example, Pfizer recently stated that a 3rd shot of their vaccine would restore a 95.6% efficacy against COVID. I assume that means that it is extremely unlikely for me to ever catch COVID to begin with.

But I wonder, is there another number associated with the efficacy against serious illness? Like say Pfizer is 95.6% against initial infection but 99% against serious illness?

submitted by /u/Alipoet
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Is a "well exercised" immune system better at fighting off an unknown pathogen? Or, conversely, can an immune system be too well exercised?

Posted: 20 Oct 2021 06:22 PM PDT

By "exercised" I mean exposure to many different pathogens, although not necessarily ones closely related to a new pathogen.

By "too well exercised" I don't mean in the short term, while actively fighting off an infection, but could there be such a thing as too many different kinds of T-cells or anything?

submitted by /u/pelican_chorus
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