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Tuesday, August 22, 2017

Is an X-ray essentially a camera that operates on a higher frequency of light?

Is an X-ray essentially a camera that operates on a higher frequency of light?

Is an X-ray essentially a camera that operates on a higher frequency of light?

Posted: 22 Aug 2017 03:11 AM PDT

Is an X-ray (the machine) essentially a camera that operates on a higher frequency of light? If so, could we hypothetically make a Gamma ray camera? an AM/FM camera?

submitted by /u/nattack
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Is all stainless steel manufactured in an electric arc furnace?

Posted: 21 Aug 2017 11:38 PM PDT

Do they ever use alternative processes to make stainless steel or is this particular type of steel always manufactured in an electric arc furnace?

submitted by /u/ygh552
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How does taking potassium iodide help with radiation?

Posted: 21 Aug 2017 09:39 PM PDT

Follow up question: whats the difference between iodide and iodine? Do they do different things or is the only difference in their composition

submitted by /u/lukes1230
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Can Radiation kill someone instantly?

Posted: 21 Aug 2017 05:20 PM PDT

Less assume, for arguments sake, that instantly here means 1 minute or less.

Also is there a correlation between the mass of an object and how much Radiation it can give out? A formula? does it change by type, like gamma, alpha, or neutron?

submitted by /u/141_1337
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How does the rotation of an Earth-like planet affect its weather?

Posted: 22 Aug 2017 07:22 AM PDT

I imagine that fast spinning planets would have very volatile weather and slow spinning planets have very strange weather at sunrise and sunset. Is this true? How does the planet's rotation affect the weather patterns?

Of course I'm assuming planets similar to earth that have atmosphere.

submitted by /u/photolouis
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Why is solubility of gases inversely proportional to tempreature?

Posted: 22 Aug 2017 07:20 AM PDT

This question came when talking with some friends about saunas after a scuba trip. Why does gases get less soluble when the temperature increases? For normal reagents, it is directly proportional. Why is it different?

BTW, could you explain why solubility of normal stuff increases as temperature increases? If it is an equilibrium process, and dissolution mean the formation of intermolecular bonds (exothermic), wouldn't an increased temp discourage dissolution by le chatelier's principle?

submitted by /u/LatitudeSurfer
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Where exactly would one look to find moths during the day and butterflies at night?

Posted: 21 Aug 2017 06:09 PM PDT

Google has failed me hard on this one, saying only things like "they find a hiding place" which really doesnt tell me anything about the kind of hiding place one could find moths. For some reason I'm really curious where one would find them. Do they look for dark places to hide? If so how do they know when to venture out at night? Then I thought about Butterflies at night and my mind fell deeper into this question. Do butterflies hide in moths spots and move out when the moths return from the night at sunrise? I need to know :(

submitted by /u/Shabakanoid
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How do felines know when they are fighting or just playing around?

Posted: 21 Aug 2017 02:06 PM PDT

Felines normally play with their siblings or "friends" by scratching and biting, how do they know they are not in danger and how do they know they don't need to fight for their lives?

submitted by /u/iagooliveira
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Are humans the only species that can get a tan?

Posted: 21 Aug 2017 01:32 PM PDT

What exactly causes wind/air flow and how does it work?

Posted: 21 Aug 2017 08:14 PM PDT

Is there a difference in nutrition between a cheese sandwich (bread, butter, cheese) and a grilled cheese sandwich (bread, butter, cheese + heat)? Is one more healthful than the other? Does cooking it affect things the same way it does certain vegetables etc?

Posted: 21 Aug 2017 01:20 PM PDT

Why is Plutonium considered to be so dangerous?

Posted: 21 Aug 2017 06:55 PM PDT

It has a very long half life so it's not throwing out a lot of radiation, yet it is still considered to be bad.

submitted by /u/General_Landry
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What causes neutron degeneracy to break down when a neutron star becomes a black hole?

Posted: 21 Aug 2017 09:33 AM PDT

From what I've read about how degeneracy works, it's not something that can 'fail', as such: it's absolutely forbidden for particles to share a quantum state, so they resist compression past the point where they would have to. When electron degeneracy 'fails' at the Chandrasekhar limit, that's not the electron degeneracy itself failing-- it's that it becomes energetically favourable for the protons and electrons to react to form neutrons. So what happens at the upper limits of pressure for a neutron star, when it becomes unable to resist gravitational collapse? Do the neutrons react into something else, do they just get dense enough that an event horizon forms, or do they somehow start violating degeneracy?

submitted by /u/ConcernedInScythe
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How much heat does the reflected sunlight off the moon give Earth?

Posted: 21 Aug 2017 09:46 PM PDT

What makes a material better or worse heat conductor on a molecular level?

Posted: 21 Aug 2017 07:31 PM PDT

I imagine there are a multitude of reasons for a material to be better at conducting heat then another, but I was wondering if there was a more "fundamental" characteristic of a material that could justify it all other factores ignored.

submitted by /u/lokedan
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Why are there so many craters on the moon but not on earth?

Posted: 21 Aug 2017 08:16 PM PDT

Why are humans more susceptible to allergies than animals?

Posted: 21 Aug 2017 02:13 PM PDT

I meet people all of the time who have allergies to different types of food and animals. But I rarely hear of animals being allergic to certain foods or humans/other animals. Why is this?

submitted by /u/BenjiManCan
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Is there a solution to the three body problem?

Posted: 21 Aug 2017 12:22 PM PDT
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Monday, August 21, 2017

Will we ever know if Pi is a "normal" or "non-normal" irrational number? Is it within the realm of possibility that we will ever find out?

Will we ever know if Pi is a "normal" or "non-normal" irrational number? Is it within the realm of possibility that we will ever find out?

Will we ever know if Pi is a "normal" or "non-normal" irrational number? Is it within the realm of possibility that we will ever find out?

Posted: 20 Aug 2017 02:02 PM PDT

According to what I've heard, a "normal" irrational number is one whose digits contain every conceivable combination of numbers (including, for example, the social security numbers of everyone who has ever had an SSID in alphabetical order), while a "non-normal" irrational number is one whose digits are infinite but do not contain every possible combination of numbers.

So I guess I have two questions:

1) Will we ever know which of these categories Pi falls under

and

2) How is it possible to have an infinite number of non-repeating numbers without any patterns that doesn't eventually run through every possible numeral combination?

Edit: thank you for all the awesome answers! I now totally understand question #2 and would like to propose another question for anyone who sees this after this edit:

What is an example of a normal irrational number and how can we prove that a number is normal? (Is a normal number defined as any irrational number that contains all the digits of its respective base an infinite number of times...or...?)

submitted by /u/starbounder333
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If Mars at some point had oceans that were filled with life similar to our own, would there still be oil there despite the harsh Marian conditions and what we know about the planet?

Posted: 21 Aug 2017 05:51 AM PDT

The liver breaks down alcohol, but what does it break it down into?

Posted: 20 Aug 2017 04:09 PM PDT

Basically the title

submitted by /u/GeorgieWashington
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Are there any noticeable differences in the behavior of pets raised in different cultures?

Posted: 20 Aug 2017 08:21 PM PDT

Why do most of the tall structures have a needle type thing on top of them?

Posted: 20 Aug 2017 07:15 PM PDT

Like in this picture - https://drive.google.com/file/d/0B5gYDDbu6LmQOXVMZEdDa21LZ0k/view?usp=drivesdk I am new to reddit, I didn't know where to ask, but hope you guys understand me.

submitted by /u/malivp3494
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Why are lightning bolts blue?

Posted: 20 Aug 2017 03:43 PM PDT

Please clear things up for me about the Great Barrier Reef. How much is gone, how much is bleached, can it be saved, what are the long term effects?

Posted: 21 Aug 2017 05:50 AM PDT

Why do eyeglasses "work" even when held at arm's length?

Posted: 20 Aug 2017 04:45 PM PDT

My understanding is that myopia makes images focus in front of the retina. Let's say that in my case it's 1cm. If I pulled my glasses forward 1cm, shouldn't it be the same as having uncorrected vision? Instead, I can see things clearly (even if a little distorted) if I look through eyeglasses even if I hold them a metre away from my eyes. How does that work?

submitted by /u/awh
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If a planet is a gas giant, where does the sky start and the body of the planet begin? Is the entire planet just sky?

Posted: 21 Aug 2017 06:58 AM PDT

Is it possible for meteoroids carrying microorganisms from Earth to travel to another planet, such as Mars, and seed life onto them?

Posted: 21 Aug 2017 12:01 AM PDT

And if possible, how likely is a situation like this to occur successfully?

submitted by /u/Atomo500
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When a meteor impacts the moon, does the Earth feel any consequences?

Posted: 20 Aug 2017 08:24 PM PDT

I understand that very small meteors impact the moon somewhat frequently, but as indicated by the surface of the moon, much larger meteorites have struck it as well.

Assuming a reasonably sized meteor, at what point does a meteor destined to strike the moon pose a risk to Earth? And as a follow up, in what way(s)?

submitted by /u/Scuzzboots
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Are there different "invisible" inks that can only be seen from different UV wavelengths?

Posted: 20 Aug 2017 12:11 PM PDT

For example, could you have one of those hidden message pens sold in stores that couldn't be viewed by another different pen because it uses a different wavelength of light? Or are all the inks visible from any UV light?

And aside from theoretical, is this already a thing?

submitted by /u/Kymysto
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Would a jar that had an absolute vacuum float or sink in water or air?

Posted: 20 Aug 2017 11:23 PM PDT

How to visualise unpolarised light?

Posted: 21 Aug 2017 02:15 AM PDT

I initially thought that unpolarised light was just a single pair of electric and magnetic field waves changing rotations really quickly, giving it the effect of having "random" rotations.

Secondly, I thought of quantum effects being present, where the wave position and rotation would be in superposition until it was observed. But this doesn't make sense, as this would mean you could polarise light just by looking at it. (or the wave function collapses into a point photon, which has no polarisability)

I've read on several websites that unpolarised light is basically both the electric and magnetic fields of light, oscillating in random directions and at different phase differences.

So does it seem that the unpolarised light following the direction of the wave could be visualised as a cylinder? The radius of it being the amplitude of the waves, to be clear. In addition, the "volume" of this cylinder consists of fluctuations in both the electric and magnetic field.

submitted by /u/LECAGO
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Why is the lather of a soap always white, no matter it’s original colour?

Posted: 20 Aug 2017 11:35 AM PDT

Why is Pluto's argument of periapsis 113°?

Posted: 21 Aug 2017 04:52 AM PDT

Looking up the argument, it is quoted as 113.834° (Wikipedia).

This implies that Pluto is closest to the Sun when it is 113° from the first point of Aries, i.e. when it is in roughly the 24th point of Cancer.

However, Pluto was last at perihelion in 1989, when it was in mid-Scorpio. I would have expected its argument of perihelion to be more like 225° based on this knowledge...

Why doesn't the argument of perihelion point to the correct location?

NB: this is not an issue of axial precession and the drift of the constellations with respect to the tropical Zodiac co-ordinate system, that shift is less than 30°, and does not explain this large offset.

submitted by /u/SolFreer
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How are there different forms of ice and how do they work?

Posted: 20 Aug 2017 09:01 PM PDT

I've read that there can be all different types of ice. That don't necessarily have to be cold. Mainly on other planets and stuff, but how is this possible and how does this work? How can it have more than one solid form? Is "hot ice" a thing just held together by pressure and not temperature at all?

submitted by /u/a-blessed-soul
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Do people with artificial hearts burn less energy?

Posted: 20 Aug 2017 01:09 PM PDT

edit: After doing some research it seems artificial heart tech is far less portable than i had thought

submitted by /u/strategosInfinitum
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When did different eye colors emerge in humans, and do we know anything about ancient ancestral eye color?

Posted: 20 Aug 2017 10:49 AM PDT

Why does the USS Indianapolis seem to be in much better condition than the Titanic when it was first found, when the amount of time between the sinking and discovery of each ship was about the same?

Posted: 20 Aug 2017 12:18 PM PDT

The rate of obesity has increased worldwide in recent years. What effect does genetics have on obesity, and are there any specific genes that have a larger impact than others in determining risk of obesity?

Posted: 20 Aug 2017 04:01 PM PDT

If the color white reflects all light and mirrors reflect all light, why don't they look the same?

Posted: 20 Aug 2017 01:37 PM PDT

How are flu vaccines made every year before flu season?

Posted: 20 Aug 2017 06:35 PM PDT

AFAIK, the flu changes and adapts every year requiring us to get the shots every year but how are they made before the new flu strain is even out?

submitted by /u/DangerousViews
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Sunday, August 20, 2017

Do all organisms perceive the passage of time at the same rate?

Do all organisms perceive the passage of time at the same rate?

Do all organisms perceive the passage of time at the same rate?

Posted: 19 Aug 2017 09:18 PM PDT

Or would a minute seem longer for a frog than a ferret, for example?

submitted by /u/perimason
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Is it possible to have a "reverse" Placebo effect?

Posted: 19 Aug 2017 02:47 PM PDT

Which means even after you take a functional pill, it just won't have any affects, just because you think it is a Placebo pill. Thanks in advance

submitted by /u/RafikiTheWiseBaboon
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Why did the radiation from Hiroshima not last as long as the chernobyl disaster?

Posted: 20 Aug 2017 05:35 AM PDT

Was it the power of the explosion blowing the radiation away or was the bomb designed in such a way as to avoid long lasting fallout?

submitted by /u/the_wild_skunk
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Would a helium filled drumset sound higher in pitch or just not work?

Posted: 20 Aug 2017 02:47 AM PDT

In case you're wondering, no, I didn't find anything on Google

I do have a drumset, just not the helium

And sorry for the stupid question :')

submitted by /u/Chouras56
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[LONG][CONFUSION]Violation of Lenz's law in magnetic interaction between a conducting ring and a moving magnet?

Posted: 20 Aug 2017 07:11 AM PDT

This post is going to be a bit long, but mostly because I am going to explain all the math behind my confusion. Feel free to skip the math to reach the conclusion. I have marked different sections in the post for your convenience. Please go through the effort of reading this, as this is really nagging my mind and I have gone through some effort to type this out too ;)!

THE PROBLEM

In our physics class we were posed this question: Suppose a magnet whose dipole moment is M is located on the axis of a conducting ring of radius a and resistance R, at a distance x from it's centre. The magnet is moving with a velocity of v towards the ring. This is the figure. What will be the force on magnet? It is given that a may not be very small compared to x.

THE SOLUTION

Since a is not very small compared to x, we cannot use the inverse cube laws for field due to a dipole. So what we did was, we replaced the magnet with a ring with radius b very small compared a, with a current of i2 through it. Now we calculate the mutual inductance between the two rings. Since b is very small in comparison to a, mutual inductance comes out to be

uoa2πb2/(2(a2+x2)3/2)

(We get this by calculating flux due to field of ring with current i1, linked with the ring which replaces the magnet, then dividing this flux by i1.)

So to get the flux due to field of magnet on the original ring, we simply multiply this mutual inductance by i2 (current through the ring which replaces the magnet). So we get flux as

uoi2a2πb2/(2(a2+x2)3/2)

But i2πb2 = current x area = magnetic dipole moment of magnet = M

So flux due to magnet through the ring is

uoMa2/(2(a2+x2)3/2)

Since x is changing (the magnet is moving), this changing flux through the ring produces a current due to induced emf in the ring.

This current will be emf/R = time derivative of flux / R.

So differentiating the value of flux which we calculated, we get the current in the ring as

i = 3uoMa2xv/(2R(a2+x2)5/2)

Now, this current produces a magnetic field B = uoia2/(2(a2+x2)3/2 at x distance from it's centre on its axis.

So we put in the value of i to get magnetic field due to ring on the magnet M.

B = 3uo2Ma4xv/(4R(a2+x2)4)

Potential energy of magnet M is U = -M.B = MB. And force on the magnet is F = -dU/dx

So putting in value of B in MB, and differentiating with respect to x, we get

THE CONCLUSION

F = 3uo2M2a4v(7x2-a2)/(4R(a2+x2)5)

So this is the force due to ring on magnet.

THE CONFUSION

Now here in lies my confusion. This formula should work for all values of x. So when we plug in values of x smaller than a/sqrt(7), we get the force on the magnet to be attractive! But lenz's law says it should be repulsive. Now our physics teacher explained the reason behind it:

The magnetic field lines when the magnet is close to the ring looks like this. Notice the some of the field lines cross back into the ring plane. So the magnetic field lines is a mixture of "dots" and "crosses" through the ring. So at some point, the rate of increase of dots counters the rate of increase of crosses, and thus the ring develops a south pole when looked from the magnet, and thus the ring attracts the magnet.

Now this seems a perfectly legit explanation, and the math checks out, but I have a huge question regarding this.

Suppose the magnet is given a velocity v towards the ring at a distance of a/sqrt(7) from the centre of the ring. The ring will attract the magnet, as proved above. When the magnet crosses the centre of the ring, there is a current flowing through the ring AND the velocity of the magnet is more than v. So obviously the energy of the system has increased, with no source of energy input, rather, there is dissipation of energy due to current. Where does the extra energy come from? Is this a violation of law of conservation of energy?

submitted by /u/rusty_ballsack_42
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How do spiders survive in dark isolated areas?

Posted: 19 Aug 2017 05:40 PM PDT

Everyone is familiar with basement spiders or abandoned building cobwebs. My question is: How do these arachnids survive (and seemingly thrive) indoors in the dark away from any abundant food source (bugs)?

submitted by /u/pawsibility
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Does a Faraday Cage needs to be grounded to effectively work?

Posted: 19 Aug 2017 06:23 PM PDT

My concern on this question is especially in the case of microwave oven. Does it matter for signal leak if the microwave is grounded or not?

submitted by /u/Finnthebroken
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Do any wild organisms have a symbiotic relationship with another to babysit their young?

Posted: 20 Aug 2017 02:02 AM PDT

Is there some species that plays host to effectively keep vulnerable young animals together and away from predators until the parents vocalize a call and the offspring retreats to them? Like a hollow plant nursery that wants fertilizer or sharing a kill with something that has its own young that can occupy the other's young's time?

Earth is amazing, I refuse to believe no organisms have cashed in on this small stretch in behavior or morphology.

submitted by /u/pimpmastahanhduece
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Why do we get eye gunk?

Posted: 19 Aug 2017 06:21 PM PDT

I was wondering specifically why we get eye gunk while sleeping or at least why it's there when we wake up.

I'm confused as to how it's produced, what it really is, and the purpose behind it - is it just to keep eyes shut? If so can eye gunk be produced with prolonged periods of shut-eye whilst still mentally awake?

submitted by /u/ury17
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How long does a beam in the Large Hadron Collider last before they have to dump it?

Posted: 19 Aug 2017 03:50 PM PDT

I read online 10-20 hours but I'm not sure if that's outdated information.

submitted by /u/TheIncorporeal
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Why is wind louder when you face it and quieter when it goes directly into your ear?

Posted: 19 Aug 2017 07:45 PM PDT

Is it possible for an object in space to be stationary?

Posted: 19 Aug 2017 07:26 PM PDT

To clarify, is it possible for an object that is beyond the gravitational pull of a planet or other large object to remain stationary, relative to everything else that is orbiting or otherwise traveling? Thank you for indulging the ranks of the ignorant.

submitted by /u/GustavoShine
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Understanding Energy from Lagrangian mechanics?

Posted: 20 Aug 2017 03:59 AM PDT

For a long time, I've tried to understand what energy is, and why it's conserved, given that force could be created and destroyed, why is it that certain systems would have a quantity that defines it's ability to transfer work and it's always conserved. Besides Noether's theorem, how does Lagrangian mechanics explain why energy is always conserved? To me, analyzing various systems would give me great detail of the topic, if certain forces are applied there usually is another force(s) that opposes it(mechanics: friction, electrodynamics: Lorentz), how does this fit into Lagrangian mechanics?

submitted by /u/BRP106
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What is happening on a cellular/tissue level when someone loses their voice?

Posted: 19 Aug 2017 05:04 PM PDT

Why is there a post-storm haze?

Posted: 19 Aug 2017 06:14 PM PDT

After the thunderstorm and tornado warning today, the general outdoors seemed brighter than normal and had a green hue to it. I only remember seeing this once before, also after a storm. Is the storm the cause, and if so what is happening? (flair added tentatively, not sure where this fits but it needed one)

submitted by /u/TechnoEnder
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Because of gravity's constant effects, is there infinite energy in the universe?

Posted: 19 Aug 2017 11:31 AM PDT

So it's been a while since i've taken a physics course, but the last one I did take was grade 11 physics. One of the major units we learned about there was energy, and a big part of that was the kinetic vs potential energy balance. Now we also learned that energy is always conserved so it cannot be created or destroyed, but this never sat quite well with me.

Say we have two apple trees. One at the top of a hill, and one at the bottom of the hill. The trees grow their apples, and when they are ripe enough they fall to the ground. Now the apples at the bottom of the hill just fall straight down to the ground and stop, but the apples at the top of the hill fall straight down, and then roll down the hill. This means that for the apples on the top of the hill, they have a greater potential energy before they fall, and greater kinetic energy during the fall and subsequent roll.

Now normally you have to lift something up against the force of gravity, for it to gain potential energy, but in this case, there is no extra energy expended to put the apples in a higher location gaining that extra potential and kinetic energy. In other words, both apple trees are expending the same amounts of energy to grow the apples, but the ones of the top of the hill will generate more energy when falling, purely because of their location.

So it seems like in this scenario, we have a situation where two of the same objects have differing levels of energy based off location in space, but no energy input was required to create that difference in location. And because energy cannot be created, my only explanation for this is because of gravity's constant force on everything with mass, there is infinite energy.

Sorry for the long post, but I hope this can be answered as it's really bugging me. Thanks.

submitted by /u/Warriorjrd
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Why dont all polar liquids act the way ferrofluid does?

Posted: 19 Aug 2017 03:15 PM PDT

Ive been told that ferrofluid works because in a magnetic field, tge magnetic poles of the suspended magnet line up, attracting in the direction of the field and repelling orthogonally. In that case, why dont electrically polar liquids like water have the same reaction in an electric field?

submitted by /u/chunkylubber54
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Why does rifling help bullet accuracy?

Posted: 19 Aug 2017 09:18 AM PDT

How are closed-loop steel cables used in e.g. ski lifts made?

Posted: 19 Aug 2017 12:56 PM PDT

Is it first made as a long cable that is then closed in a single place, is it woven in a more continuous way, or is it made in a different way?

submitted by /u/MrShortcut
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