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Saturday, April 29, 2017

Why are car antennas so small now, when 10 years ago they were 2-3 feet tall?

Why are car antennas so small now, when 10 years ago they were 2-3 feet tall?

Why are car antennas so small now, when 10 years ago they were 2-3 feet tall?

Posted: 28 Apr 2017 07:05 PM PDT

What happens to your muscle when you sprain it?

Posted: 28 Apr 2017 06:49 PM PDT

Why do slugs/snails dislike plants such as California Poppies?

Posted: 28 Apr 2017 01:10 PM PDT

From my own gardening experience, I know that slugs and snail don't like California poppies (and some gardening sites say the same) along with some other plants, but was wondering what is it that they dislike? Do they the plants contain a chemical that the slugs/snails don't like?

submitted by /u/bluemuffin78
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When someone dies of exposure, what exactly kills them? Do other animals die from exposure?

Posted: 28 Apr 2017 06:12 PM PDT

What are the advantages/disadvantages to using LN instead of co2 in supercritical extractions?

Posted: 28 Apr 2017 02:17 PM PDT

What is the difference in their extraction profile?

submitted by /u/PorkChopXpresss
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Are ergodic processes always stationary?

Posted: 29 Apr 2017 02:57 AM PDT

If a process is ergodic does that necessarily entail that it cannot change over time?

Asking in relation to Friston's Free Energy framework that assumes living systems are ergodic, but a question has been raised that ergodic processes are necessarily stationary, and living systems are not stationary, so they cannot be ergodic. However I have read about specifically 'stationary ergodic processes', which implies that not all ergodic processes are stationary.

Any clarification greatly appreciated. Thank you.

submitted by /u/Paranoid4ndroid
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Besides the radioactive element, are superheavy elements just like normal elements?

Posted: 29 Apr 2017 06:30 AM PDT

[Physics] Do light particles ever bounce off of each other?

Posted: 28 Apr 2017 02:10 PM PDT

I bought pollen free sunflowers seeds by accident. But how did the seller create these seeds in the first place?

Posted: 28 Apr 2017 02:30 PM PDT

My Google fu has failed me!

Quote from a seller of pollen-free sunflowers:

" We actually develop all of the sunflower varieties that we sell by conventional plant breeding. No genetic engineering, no GMO. It's a long process that takes at least 7 years from start to finish before we can produce the seeds."

Okay, cool.

"The fact that our varieties are pollen free means that they cannot pollinate themselves and therefore will not breed true from any seeds that you might find in heads after flowering."

So how can they get pure-bred sunflower seeds when the breed cannot create pollen, thus cannot be fertile, thus cannot create seeds?

Even if it was GMO, how do you get the engineered plant, how do you get that one to produce fertile, non-hybrid seeds?

submitted by /u/IrisHopp
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The 'Oh My God Particle' was estimated to have a kinetic energy of about 48 Joules. What would it feel like to be hit by this atomic nuclei?

Posted: 28 Apr 2017 09:42 AM PDT

Here is the link to to the PBS Spacetime video on youtube explaining the 'Oh My God Particle' and other cosmic rays: The Oh My God Particle Quoted energy is at about 1 minute.

 

In the video he equates it to a "good size stone thrown at your head at 50 miles per hour." I assume the particle would pass through me 99.9% of the time unobstructed. But if my body were to stop it, would I even feel it? What would it feel like? Could it damage internal organs?

 

Thanks for any insight!

submitted by /u/idontknowdogs
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How were mathematical models fit from experimental data before computers?

Posted: 28 Apr 2017 09:52 AM PDT

In other words, how was curve fitting performed? Particularly for more complicated models.

submitted by /u/njm37
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Since things like neutron stars and black holes can bend light, can light orbit around them? What would we see if we looked at the orbiting light?

Posted: 28 Apr 2017 12:29 PM PDT

Do portable magnet detectors exist?

Posted: 28 Apr 2017 09:58 PM PDT

I'm looking for an instrument that could help me detect when I'm within 1-2 meters (6 ft) of a small neodymium magnet while being outside in the city, and could perhaps even help me pinpoint its location. Sorry if this goes against the rules, but I'm having one hell of a time finding an answer to this.

submitted by /u/cliffdiv3r
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How did people isolate charge(s) to study it before they knew what it was/that it was discrete?

Posted: 28 Apr 2017 08:43 PM PDT

How do processors (Qualcom) have an effect on charging speeds? (Quickcharge)

Posted: 28 Apr 2017 03:32 PM PDT

I cannot wrap my head around this. How does a processor dictate how fast a charger can charge?

For example, Quickcharge 4.0 needs a Snapdragon 835 processor or higher.

From a novice Computer Engineer standpoint, I can understand circuits and battery dictating charge speed but not the processor.

submitted by /u/DefinitelyNotHomeles
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Could dropping a hairdryer in a bathtub really kill a person?

Posted: 28 Apr 2017 11:33 PM PDT

From a non gfci source of course. Wouldn't the rush of current cause the overcurrent protection to trip regardless? In a larger volume of water would more of the current dissipate?

submitted by /u/bermysander
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Why do handheld glass magnifiers get smaller as the strength of the magnification increases?

Posted: 28 Apr 2017 11:32 PM PDT

I work with seniors and individuals with low vision. We show them various types of magnifiers and how to use them to be independent. I have the hardest time explaining to them that getting a larger strength handheld glass magnifier means that the circumference will be smaller not larger. I would like to understand this better so I am clear and correct when explaining to others.

I say handheld glass to differentiate between a glass magnifier set in plastic and video magnifiers that can magnify multiple times using video imaging.

submitted by /u/WanderDrift
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What is the speed of quantum tunneling?

Posted: 28 Apr 2017 12:15 PM PDT

as in how many times faster then the speed of light would it be

submitted by /u/joaosturza
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How did stone-aged people fell trees?

Posted: 28 Apr 2017 10:36 AM PDT

I've seen videos of stone tools felling smaller trees and shrubs, how did people without access to metal tools chop down something like a large oak tree? Was it ever even done?

submitted by /u/Kombaticus
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How does sublimation work on a molecular level? Is there really no period of time between solid and gas or is the transition instant?

Posted: 28 Apr 2017 11:40 AM PDT

I'm thinking is terms of planck time or quantum time.

submitted by /u/on_those_1960s
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What makes water so significant for searching for potential life?

Posted: 28 Apr 2017 09:32 AM PDT

I've been watching a lot of videos on YouTube about the Drake equation, potentially habitable planets, planets with potential life, etc. and I got to wondering why is water so significant to a planet potentially having life? Is it just because of our observations of biological life on earth? Is it not plausible that there could be life forms that can live off of other elements or gasses like CO2? I'm not super familiar with this kind of science, as I am a software engineer, so I apologize if this question is redundant.

submitted by /u/chrisrod369
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Friday, April 28, 2017

Are there any poisons/toxins which, if taken separately, are fatal, but if taken simultaneously, are not?

Are there any poisons/toxins which, if taken separately, are fatal, but if taken simultaneously, are not?

Are there any poisons/toxins which, if taken separately, are fatal, but if taken simultaneously, are not?

Posted: 27 Apr 2017 06:31 PM PDT

What's reference point for the speed of light?

Posted: 28 Apr 2017 02:42 AM PDT

Is there such a thing? Furthermore, if we get two objects moving towards each other 60% speed of light can they exceed the speed of light relative to one another?

submitted by /u/IwishImadeSense
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Do x-rays have depth of field like regular cameras do? How do things look in an out of focus X-ray shot?

Posted: 27 Apr 2017 09:03 AM PDT

Do our brains process faces differently as we age?

Posted: 27 Apr 2017 02:39 PM PDT

For example, a five year old looks at a picture of the face of a ten year old and thinks they look old and mature, whereas if the child looks at that same picture ten years later, he'll probably think the ten year old looks childish. Can this be explained in the brain?

submitted by /u/JoeCool888
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How is linearity of quantum mechanics compatible with non-linear systems higher up?

Posted: 28 Apr 2017 06:20 AM PDT

One striking property of the Shrodinger's Equation is that it's linear - if I want to compute the evolution of a sum of waves, I can just compute for each wave and add the results up.

However, if you compose linear functions, aren't you always suposed to get linear functions? How can complicated systems (macro objects) exhibit non-linear behaviour if they are composed of linear parts? Especially confusing is the squared modulus rule for probabilities of measurement - where the hell does that come from? Squaring is pretty obviously nonlinear. How come?

submitted by /u/thetimujin
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Why does the tricuspid valve have 3 cusps and the mitral valve have 2 cusps? Why is there a difference?

Posted: 27 Apr 2017 05:52 PM PDT

When something exceeds its half-life, what does it become?

Posted: 28 Apr 2017 07:28 AM PDT

More directly, a muon has a half-life of 2.2 seconds. What happens after those 2.2 seconds? What does it become?

submitted by /u/Solmeaus
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What does the colour of gas giant planets, like Jupiter's Red Spot come from?

Posted: 27 Apr 2017 01:50 PM PDT

Why does Ice behind the ear mitigate a Vasovagal response?

Posted: 27 Apr 2017 06:08 PM PDT

There are many things that can trigger a Vasovagal response. One of the most common is having blood drawn. The affected may feel dizzy, nauseous, or may even faint. A lesser known treatment is to hold ice behind the ear (corresponding to the arm giving blood) for about a minute before and throughout the drawing of blood.

Physiologically, why does this help mitigate a Vasovagal response?

submitted by /u/thegreatroe
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Gravitons, Where do they come from? Are they a field like the Higgs Boson?

Posted: 27 Apr 2017 07:15 PM PDT

Hey guys, Im reading Steven Hawkins "The Universe in a Nutshell" and I'm confused on gravitons. I get photons being a release of energy as an electron moves down an orbit and I understand the particles that have to do with the weak nuclear force, I just don't understand the origin of gravitons. Are they emitted from interactions of particles or are they a field? Thanks!

submitted by /u/TheBoulder101
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Why does going from 20 or 30 frames per second to something like 60 cause an image to appear smoother (faster?), but going from 60 fps to 120 fps cause video to appear in slow motion?

Posted: 27 Apr 2017 01:35 PM PDT

Is it theoretically possible to reach space in a hot air balloon?

Posted: 27 Apr 2017 04:57 AM PDT

How do we determine an accurate half life of an isotope?

Posted: 27 Apr 2017 06:30 AM PDT

I have a general understanding of what half lives are and how we date things using them. My question is this -- how do we determine the actual rate of a half life for something beyond our immediate observable timeline?

For example, for potassium-40 the half life is considered to be about 1.3 billion years. Since we cannot directly observe that amount of time, how do we arrive that that is the correct half life? Is there a constant decay of the isotope that we can then project how long it would be for a half life? And if this is the case, how can we accurately factor in cases where exponential decay may occur?

Thanks for your time in answering my question. I apologize if this has been answered before and I was unable to find it -- still new to reddit.

submitted by /u/The_Nameless_Deity
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Are there any negative effects to long-term exposure to high-frequency/ultrasonic sounds like in animal repellent devices?

Posted: 27 Apr 2017 11:07 AM PDT

Looking for information related to mental and physical effects on children and young people specifically, but also in general.

The reason for this post is to find reputable sources that relate to the topic. Answers are fantastic, but appreciate citable resources as well.

submitted by /u/Cianistarle
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[Physics] How are electrons in an atom distributed?

Posted: 27 Apr 2017 04:59 AM PDT

So I'm fresh out of high school and what they taught us about the atomic model was niels bohrs model(I think) , with the definite locations of electrons arranged in shells around the nucleus. Thing is I recently stumbled across it online that this was extremely outdated and apparently what's now used is the electronic cloud model, can someone explain to me how this works? I tried reading about it but could only grasp about 50% of it. Some parts of it were just too complicated like, "an electron exists everywhere in the atomic at the same time" I can't seem to understand this part perfectly.

How do electrons in an atom exist? As waves or as particles? How are they spaced out, can they be pinpointed at a particular point?

submitted by /u/Temilitary
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Are there any examples of sexual reproduction that involves more than 2 gametes?

Posted: 27 Apr 2017 01:56 AM PDT

Excluding asexual reproduction, are there any examples that involve three or more gametes? If not why is there this limit throughout all taxa on earth?

Thanks!

submitted by /u/Qontinent
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Thursday, April 27, 2017

If an electric motor is supplied power but restricted in turning (like holding back a ceiling fan) what is happening which would cause it to 'burn up'?

If an electric motor is supplied power but restricted in turning (like holding back a ceiling fan) what is happening which would cause it to 'burn up'?

If an electric motor is supplied power but restricted in turning (like holding back a ceiling fan) what is happening which would cause it to 'burn up'?

Posted: 26 Apr 2017 10:31 PM PDT

If a redwood or pine tree were to live in the perfect conditions, with enough nutrients and without pests or disease or deforestation. Could the tree live forever?

Posted: 26 Apr 2017 09:41 PM PDT

Why is greenhouse gas one way?

Posted: 26 Apr 2017 07:48 PM PDT

So green house gas like CO2 supposedly keeps heat inside the atmosphere, but if it doesn't let heat back outside the atmosphere, why can heat get inside in the first place?

submitted by /u/scottymooney
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Why do things seem to start spinning the other way after reaching a certain speed?

Posted: 26 Apr 2017 07:45 PM PDT

If, instead of electromagnetic force, Magneto had control over the weak nuclear force, what would be the things he could do?

Posted: 26 Apr 2017 02:30 PM PDT

assuming he can control as well as he does magnetism(even though probably it does not correlate a 1 to 1 mach)

submitted by /u/joaosturza
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130000 year old mastadon in California. There aren't signs of meat removal on the bones. How do they know WHEN the tools were used to process the bones?

Posted: 26 Apr 2017 07:59 PM PDT

How feasible is it that 13000 years ago like current science believes whatever evolution of humans found the bones and processed them for the bone 117000 years ago? The tools can't be dated, right? They are stone and could have been in the area; there's reasonable doubt unless we can tell when a rock was broken to form it with dating and I am unaware? The lack of meat removal from the bones suggests the meat was unusable for whatever reason.

Or am I just waaay left field?

submitted by /u/aftersexhigh5s
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What sort of negative consequences could result from a desert ecosystem suddenly receiving an exorbitantly large increase in rainfall?

Posted: 26 Apr 2017 07:31 PM PDT

How do fins stabilize a rocket (or any other projectile)?

Posted: 26 Apr 2017 07:07 PM PDT

Why are severe allergic reactions to peanuts and other nuts so common compared to other foods and potential allergens?

Posted: 26 Apr 2017 03:04 PM PDT

Why do we take consider a zero point at r = infinity for Gravitational Potential Energy?

Posted: 26 Apr 2017 06:07 PM PDT

I have two questions, a main one (title) and a side question I added.

1) The first one has to do with the formula for deriving Gravitational Potential Energy. I learned that, for the derivation of Gravitational Potential Energy given large distances, we have to use the mathematical analytic way to derive an expression for it at a given distance.

To do so, you need integrate F dot dr from r to infinity. However, what I don't understand are as follows:

  • Why do we need to take the zero point at r = infinity? Why can't I take it from any arbitrary point to get a general expression for its GPE when I integrate?

  • Why is the work required to push an object to that height equal to the force due to gravity times the distance? Don't I need to apply a force that overcomes the force due to gravity to even raise it to begin with? Fg * h is definitely greater in magnitude than fg, but if I'm applying work to an object equal to Fg * h in the opposite direction of where it wants to move (towards the dominant object's COM) how do I know the magnitude of that work is sufficient to do so?

If I was trying to figure out how much energy I need to give an object to raise it from one point in space to another relative to, say the Earth, I could take the change in energy from the two points. If its energy at its initial point is 2 and the energy at the point I want it to be at is 8, I need to supply 6 joules to it. But how do I reconcile that with the derivation from the above paragraph?

2) The second question has to do with zero points for potential energy. Is this allowed because, as long as the distance from each object relative to another is the same no matter where I place a zero point, everything resolves? If at point A, object 1 is 2 units from point A and object 2 is 5 units from point A (all in, say, the x axis), then I'm not cheating by taking point B to be at object 1's position and saying object 2 is now 3 units from point B, right? Wouldn't its potential energy then change here though? That's okay because it's all relative, right? But the magnitude changes.. that's okay?

submitted by /u/sangstar
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Why are Magnetars extremely magnetic?

Posted: 26 Apr 2017 12:35 PM PDT

From my knowledge of magnetism, extreme heat would remove magnetic properties from substances by messing with the spin of electrons in orbit. So why are magnetars, which reach such extreme levels of heat, still so powerfully magnetic.

submitted by /u/SuperKalkorat
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Are men more likely to part with resources in the presence of attractive women?

Posted: 26 Apr 2017 01:27 PM PDT

I recall reading studies of this nature and I'm currently writing a piece on related issues. Any help appreciated.

submitted by /u/eradicati0nx
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Why does a ray of beta particles curve more than a ray of alpha particles in an electric field?

Posted: 26 Apr 2017 01:51 PM PDT

So I know the an alpha particle consists of 2 protons and 2 neutrons and that a beta particle consists of just one electron

How is it that a ray of beta particles will curve more in an electric field than a ray of alpha particles?

submitted by /u/DiamondxCrafting
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Why does boundary flow stay attached to an airfoil?

Posted: 26 Apr 2017 12:31 PM PDT

I'm a pilot studying to be a flight instructor, and I'm really trying to brush up on my aerodynamics. I have a background in the natural sciences, but never took physics, so a lot of it is kind of "learn as I go."

From what I've come to understand, the Coanda effect really doesn't apply because we're not dealing with a fluid jet.

The explanation I've heard is that the curvature of an airfoil creates a centripetal acceleration, which creates a pressure gradient where lower pressure exists closer to the airfoil.

But there's some relationship I'm missing, because to me that seems dependent on a tendency to stay attached to the surface. As I understand it, in order for there to be centripetal force acting on the fluid, some additional force must be acting on it to keep the boundary flow attached. Otherwise, when the air diverts over the top of the wing, it would just continue unaccelerated past the upper camber of the airfoil.

So what keeps the boundary flow "attached" to the airfoil? Is it something as simple as friction?

Any help to understand all of the various forces affecting curved boundary flows would be much appreciated!

submitted by /u/Longhornmaniac8
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Why do second and third gen stars contain heavier elements that the first gen stars?

Posted: 26 Apr 2017 05:02 PM PDT

Thanks

*than

submitted by /u/Litllerain123
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Could you be struck by lightning inside a storm cloud?

Posted: 26 Apr 2017 04:58 PM PDT

If I were somehow able to suspend myself inside a storm cloud, or stood on top of a blimp or some type or airship, would I be struck by lightning? Or would the lightning ignore me and go for the tallest object attached to the ground?

submitted by /u/FourSquareRedHead
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Why is it that early human remains are so rare to find in the Americas?

Posted: 26 Apr 2017 06:21 PM PDT

I just read through an article detailing the find of a mastodon skeleton that seems to show evidence of early human tool-making and use from ~130,000 years ago. In the article they mention that early human remains are notoriously difficult to find. Why is that?

Edit: original thread

submitted by /u/Clevercapybara
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