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Tuesday, April 12, 2016

What is outside the observable universe? It it more stars and planets? Or nothing?

What is outside the observable universe? It it more stars and planets? Or nothing?


What is outside the observable universe? It it more stars and planets? Or nothing?

Posted: 11 Apr 2016 06:35 PM PDT

How well mapped is the inner solar system, resolution-wise? Like, it's safe to say we know about all objects bigger than ??? meters across? What organizations maintain lists of known objects in space?

Posted: 11 Apr 2016 09:59 PM PDT

How can black hole post-merger ringdowns occur if the No-hair Theorem is true?

Posted: 11 Apr 2016 02:39 PM PDT

From what I understand, the no-hair theorem, states that a black hole can be described by its mass, charge and angular momentum. However, a lot of simulations of merging black holes (such as this one, and this from Wikipedia) show a kind of "oscillatory" phase directly after the merger, where the event horizon is asymmetrical, non-spheroidal and warped from the merger. What properties inside, or of, the black hole would allow this asymmetry to exist? I always thought that singularities were just mathematical quirks - surely they don't appear distorted because there are two distinct singularities inside one event horizon? If this is the case, are the singularities continuing to orbit one another inside the event horizon? I suppose that could happen, but then surely they would need to move at a velocity greater than the speed of light inside the horizon.

Black hole physics are weird.

submitted by /u/Quackmatic
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If we could travel at the speed of light, would it ever be safe to travel through deep space?

Posted: 11 Apr 2016 04:13 PM PDT

Is there any theoretical way to know if you're going to collide with anything? My thinking is that in order to see something in deep space, where there is very little light and very little thermal energy to detect, it will need to be detected with energy emitted from the ship. Travelling at relativistic speed, will a pulse ever make it back to the ship in time for it to change course? Or do we need to fill space with vacuum tunnels and lighthouses to navigate it?

submitted by /u/KingOfMostWorms
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When does slang become a dialect?

Posted: 12 Apr 2016 06:35 AM PDT

When do phrases and conventions in common usage transition from being seen as slang to being part of a different dialect or a different language?

submitted by /u/whale_tamer
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How does the Doppler effect work at relativistic speeds?

Posted: 11 Apr 2016 08:13 PM PDT

e.g. If I am traveling at the speed of light towards a source of red light, to what extent is the red light blue shifted? Thank you!

submitted by /u/threeoneoh
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Why is Kepler's emergency mode fuel intensive? What is Kepler doing?

Posted: 11 Apr 2016 10:10 AM PDT

I can't find much. Does anyone know more? Do we have to wait for another announcement?

submitted by /u/MrDavidCrane
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Why wouldn't my friend's idea for "free energy" work?

Posted: 11 Apr 2016 12:02 PM PDT

This may sound like a /r/shittyaskscience question, but hear me out:

So my friend understands that virtual particle/antiparticle pairs are continuously being created and annihilated by "borrowing" energy from the future and the annihilation "repays" it back. And that when this happens on either side of a black hole's event horizon, the black hole has to "repay" the energy and loses mass while the other half escapes as Hawking Radiation.

He then reasons, that if he separates the particle/antiparticle pair with an extremely strong electric field, the energy "debt" never gets "repaid", and he has created free energy.

Obviously this wouldn't actually work, but I'm finding it difficult to argue exactly why. My reasoning is that either:

  • The antiparticle would anihalate with some of the machinery to repay the energy debt
  • The energy required to maintain such a strong field would create another particle/antiparticle pair that would annihilate with the original pair to get the energy back
  • or, the energy required would create a black hole.

Would any of these things be correct? If not, what would be the best way to explain why this system won't work?

submitted by /u/jfb1337
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Is the hearing protection with in-ear buds combined with over ear muffs simply the sum of each db value?

Posted: 11 Apr 2016 02:44 PM PDT

What sort of added noise reduction will I receive if I wear both in ear foam buds as well as over the ear protection. Can I simply add the db protection of each for a new rating?

submitted by /u/unintentional_pro
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How much do bodies/coffins move/settle within the ground if the cemetery is located on a hill. Do they move towards the bottom?

Posted: 11 Apr 2016 09:01 AM PDT

I always look at cemeteries located on large hills or mountains and wonder, are all of the bodies just sitting at the bottom of the hill on top of each other?

submitted by /u/Giraffecarafe11
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Photonic Laser Thruster - does photon energy diminish?

Posted: 11 Apr 2016 08:14 PM PDT

I understand that photons possess energy, which is related to its momentum. However, photonic laser thrusters, work by having a laser that is repeatedly reflected back and forth between the spacecraft (lightsail) and a source with mirrors. There are some things that I do not understand, though, and I would really appreciate it if someone could help me out.

1) Why is beam interference an issue, i.e. why are the mirrors designed to avoid beam interference?

2) According to the article, photons transfer energy to the spacecraft via redshift; does this mean that photons gradually loses energy? In other words, how is photon energy transferred?

3) The returning laser would also lose energy to the source, thereby exerting a force. Is the higher mass of the source preventing a significant acceleration?

submitted by /u/Ideas123_HS
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What does it mean in physics when something is said to have an "energy level"?

Posted: 11 Apr 2016 06:09 AM PDT

I've read many times that atoms have "electron shells" that have different "energy levels", with only so many electrons occupying a particular shell. And that these are regions of space that take the forms which are referred to as electron orbitals, and in each of those particular shapes, there is a 90% chance that one will "observe" an electron.

Why do they take those particular shapes? Why is it that an electron can be measured to be in one particular region of space more often than a completely different region of space?

In addition, what is to be said about the behaviour of the electron when it isn't being measured? I've heard that asking the question of what the behaviour of the electron is like when it's not being observed, is making a categorical error. That is, it doesn't make sense to ask about the behaviour of the electron, when it's not being "measured" (source: https://www.youtube.com/watch?v=UNpLfXOfzZ8). But what does that mean? Does that mean that the electron is still 'behaving' but we lack the cognitive ability to understand how it is doing so? Or does it mean that that particular electron doesn't even exist unless it is measured?

submitted by /u/Laughing_Chipmunk
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Does gravity affect the speed of gravity?

Posted: 11 Apr 2016 06:20 AM PDT

I recently learned that gravity has gravity even if it is very little. So, now I wonder if the speed of gravity is less in high gravity?

submitted by /u/creperobot
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Can acceleration change instantaniously, or is it continuous?

Posted: 11 Apr 2016 04:54 AM PDT

In the same way position cannot suddenly change (that would be teleportation), and neither can speed (that would require an infinite acceleration, and therefore infinite force), can acceleration change in zero time?

If it cannot, can da/dt? If not, what about d2 a / dt2 ? How far does it go until one of them doesn't have to be continuous?

submitted by /u/PM-ME-YOUR-DELTA-V
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Monday, April 11, 2016

What would the horizon look like if you were standing on an infinitely stretching and perfectly flat plane?

What would the horizon look like if you were standing on an infinitely stretching and perfectly flat plane?


What would the horizon look like if you were standing on an infinitely stretching and perfectly flat plane?

Posted: 11 Apr 2016 03:52 AM PDT

My understanding is that the horizon is where it appears to be because of the curvature of the Earth, and if the Earth was smaller the horizon would be closer/lower. Obviously on an infinitely-stretching plane the horizon couldn't keep going up, but where is the limit?

submitted by /u/AhrmiintheUnseen
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Can an accretion disk around a black hole become so dense that fusion begins and generates a toroidal star?

Posted: 10 Apr 2016 05:31 PM PDT

How genuine are Dr. Mehran Keshe's claims that the Earth will soon be hit by mega earthquakes which will claim around 40 million lives and will divide the continents?

Posted: 11 Apr 2016 12:06 AM PDT

Can you represent PI in a finite number of digits in any number system?

Posted: 10 Apr 2016 07:29 AM PDT

From a computer science course I know that you cannot represent the number 1/10 in a binary number system. But you can do it in a decimal number system. Is there a system where you can represent PI in a finite amount of digits?

submitted by /u/xlogic87
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How does voyager organize the data it sends us?

Posted: 10 Apr 2016 11:16 PM PDT

I just came across http://eyes.nasa.gov/dsn/dsn.html, a website that will show the deep space network activity when the DSS 63 antenna started receiving a signal from voyager 1. It got me thinking, does the data transmitted have any resemblance to a modern networking packet? If I could get a hold of that raw stream of data what would I need to do get it into something human readable? I guess the crux of the question is how does voyager structure the data it sends our way? If there are resources can you point me to where I could read? Does NASA or whoever have some sort of source code repository I could look over?

submitted by /u/hairahcaz
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How do we know we have to sleep eight hours per day? Why not six or ten?

Posted: 10 Apr 2016 11:52 PM PDT

The human hearing range goes from 20 Hz to 200 kHz, but it's wider when we are young. Is it a case of degradation or does the extra ability serve a purpose for infant and children?

Posted: 10 Apr 2016 09:48 PM PDT

I can assume that we see at our best when we are young and over time, our sight gets worse as our eyes wear out. Is it the same for hearing? Or is there a purposeful reason as to why our hearing is better when we are young (maybe something to do with language acquisition), and then we shed that ability when it is no longer necessary + casual wear out?

submitted by /u/ads8888
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Can you increase how long something glows in the dark for?

Posted: 10 Apr 2016 09:39 AM PDT

I was wondering if the brightness/intensity of light absorbed by something glow in the dark just contributes to the brightness, or also the amount of time it stays luminous for. Do different colours of light make the glow more intense?

submitted by /u/Rouge_Danno
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Is there a maximum temperature my microwave oven can heat something up to?

Posted: 10 Apr 2016 11:54 PM PDT

How can a computer program can prevent the computer from "knowing" its code? (like closed source programs)

Posted: 10 Apr 2016 06:48 PM PDT

In non open-source programs, you can't check the source code from the program, but it still executes and runs on the computer. Shouldn't there be a way to know what that code is?

From what I understand it works like a blackbox, you feed it input and it gives outputs acording to the code. But how can it prevent me from checking the code?

submitted by /u/lemonaplepie
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[Mathematics] When you type the symbol for Pi into an equation on your calculator, how many decimal places does it take into account when finding an answer?

Posted: 10 Apr 2016 09:33 PM PDT

Are new vs old tires (treadwear difference) enough to affect speedometer calibrarion?

Posted: 10 Apr 2016 07:26 AM PDT

How does a flamethrower prevent the back flow of combustion as it shoots a stream of ignited fuel?

Posted: 10 Apr 2016 01:34 PM PDT

In a flamethrower like this as the fuel gets shot out of the barrel, it gets ignited creating stream of fire.

I'm assuming the fuel gets ignited after it exits the barrel, cause in the gif, theres no visible flame at the tip of the barrel. But how does the flamethrower prevent the flame from spreading into the barrel and ignite the fuel that's being constantly spewed out? Or if not that, how is combustion of the fumes prevented?

submitted by /u/jayf95
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Is there any substantial evidence that chiropractic care is effective?

Posted: 10 Apr 2016 03:47 PM PDT

How do babies get prescriptions without being able to communicate with their optometrist?

Posted: 10 Apr 2016 04:24 PM PDT

Why do people never forget how to ride a bike once they've learned?

Posted: 10 Apr 2016 03:23 PM PDT

Why do our noses get runny when we cry?

Posted: 10 Apr 2016 11:59 PM PDT

It happens to me all the time and I have no idea why it does. Is it similar to our noses getting runny when we eat spicy food?

submitted by /u/RVD420smokedurass
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With nothing but hydrogen and oxygen, how come water isn't flammable?

Posted: 10 Apr 2016 10:09 PM PDT

It sounds like the ingredients of a bomb!

submitted by /u/refwdfwdrepost
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Is there an altitude above which the atmosphere is effectively sterile?

Posted: 10 Apr 2016 05:24 PM PDT

How long do clouds last?

Posted: 10 Apr 2016 07:11 PM PDT

There are various types of clouds (stratus, cumulo-nimbus, etc.) Are these more or less perpetual, do they merge, or do they eventually dissipate?

submitted by /u/blue_shadow_
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Can the electromagnetic absorption characteristics of carbon dioxide be accurately modeled?

Posted: 10 Apr 2016 10:24 AM PDT

Do we know how colliding black holes impart momentum?

Posted: 11 Apr 2016 12:41 AM PDT

When two stellar bodies collide with one another, we know that momentum is imparted to the newly combined body. What do we know about black holes colliding with one another?

submitted by /u/somtwo
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Did the nuclear testing during the Cold War have any effect on the climate?

Posted: 10 Apr 2016 05:28 PM PDT

I mean...how hot does an H bomb get/make its surrounding environment? Something like the Sun? If only for a moment, we set off some 2050 or so bombs between all of the countries.

We've probably all seen this time lapse of testing done...

submitted by /u/Wisdom_from_the_Ages
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Sunday, April 10, 2016

What is the meaning and cause of T-symmetry violation in the weak interaction?

What is the meaning and cause of T-symmetry violation in the weak interaction?


What is the meaning and cause of T-symmetry violation in the weak interaction?

Posted: 10 Apr 2016 04:23 AM PDT

From what I understand, the weak interaction violates time reversal symmetry, but the other forces don't. Given that T-symmetry is violated by the arrow of time, why don't the other interactions exhibit this violation? Also, what are examples of it?

I have a basic understanding that the source of C and P violation in the weak interaction is due to the weak force only acting on left-handed particles and right-handed antiparticles. Is there a similar reason for the T violation observed in the weak interaction (and only the weak)?

submitted by /u/mrwho995
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What would an atom "look" like if you were small enough to see it?

Posted: 09 Apr 2016 06:25 PM PDT

The main thing that I want to know is, would the atom look like the traditional sphere shape or something different, any additional information is welcome though!

submitted by /u/theMushypotato
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I heated up water in a food can by a heat lamp and got a strange temperature graph. Why did the temperature rise in this pattern?

Posted: 10 Apr 2016 01:32 AM PDT

A few weeks ago I was doing an experiment for my physics assignment. I had 2 cups of water that was refrigerated to near 0 degrees inside a food can with no labels and had aluminum foil over the top. I then had aluminum foil in a concave shape around the can of water and over the top. I also had white paper on the floor and next to the heat lamp so most of the light would stay in the little 'cave'. I currently don't have photos so I roughly recreated the experiment design on paint:

Birds eye view of the experiment

Side view

Obviously its not to scale but if it helps the measurements of the cans are:

  • Height: 11.5 centimeters

  • Circumference: .4 centimeters

The aluminum foil wall had white A4 paper on the outside to help it stand.

I started tracking the temperature over 20 minutes when the heat lamp was turned on when the water was ~2.4 C degrees. I tracked 5 different cans and they all similar rising temperature rates. Here's a graph of the temperature of all five cans.

Can someone explain why the water had a strange temperature rate? I initially thought that the graph would be displaying a exponential graph but instead it showed that instead.

submitted by /u/NeutralGreed
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Why does Saturn have rings?

Posted: 10 Apr 2016 02:37 AM PDT

Is it because of a property of Saturn or an event that caused it to have rings?

Also, why doesn't the matter in the rings clump together to form moons?

submitted by /u/Ptyalin
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What's the fastest moving visible star, in relation to other visible stars?

Posted: 09 Apr 2016 07:00 PM PDT

Inspired by this big dipper gif: https://www.reddit.com/r/educationalgifs/comments/4e1gch/the_big_dipper_100000_bc_10000_ad/

Which star/point of light, visible to the naked eye, is moving fastest in relation to the other stars? Are there any that will noticeably shift in the sky during the next 50 years?

submitted by /u/EatingCake
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Why doesn't dark matter collapse together to form black holes?

Posted: 09 Apr 2016 10:07 AM PDT

If they aren't really interacting what force is stopping their collapse?

submitted by /u/SYLOH
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If you travel at next to near the speed of light in space, would there be any resistance? (and you are made of matter)

Posted: 10 Apr 2016 05:42 AM PDT

If it ever got cold enough for our atmosphere to condense, how deep would the sea of liquid nitrogen, oxygen and other gases be on Earth's surface, given its current terrain?

Posted: 09 Apr 2016 09:08 AM PDT

Would you be able to see a nuclear explosion on the moon with the naked eye from earth?

Posted: 09 Apr 2016 06:57 AM PDT

Considering the nuclear bomb is 50 Megaton, and there's no clouds during night time.

submitted by /u/PatientlyWaitingfy
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How can solar sails work? Where does the momentum come from?

Posted: 09 Apr 2016 02:17 PM PDT

Solar sails work by using the momentum from photons to "push" the sail, but my understanding is that photons can only travel at c. If the photon is traveling at c, then it bounces off of the sail, still moving at c. Where did the momentum to move the sail come from?

submitted by /u/Partsofspeech87
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What happens to matter at the center of a nuclear explosion?

Posted: 10 Apr 2016 01:42 AM PDT

Civil Engg:How tuned mass damper works to resist earthquake vibrations? How it is tuned to the building?

Posted: 09 Apr 2016 11:20 AM PDT

As tuned mass damper is usually light weight ball compared to building which is attached on top of building and move out of phase relative to it.

submitted by /u/Khurram_mehdi
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Why does electricity form and cause lightning in a volcanic eruption?

Posted: 09 Apr 2016 09:56 AM PDT

Is there ever any variation between the individual Gs, As, Ts, and Cs of a single DNA strain?

Posted: 10 Apr 2016 01:16 AM PDT

Clarification because I really know very little about DNA so my question might sound like gibberish: Can two separate G "connectors" be slightly different when compared or all they all identical?

submitted by /u/clymo
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Do high energy electrons interact chemically with conpounds?

Posted: 09 Apr 2016 06:45 PM PDT

I want to know if free electrons such as in a cathode ray tube interact chemically and if do how?

If they do could you use them to cause a reduction half reaction without an associated oxydation?

submitted by /u/browncoat_girl
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What are + and x modes of gravitational waves?

Posted: 09 Apr 2016 01:55 PM PDT

I am currently reading a publication of Tomimatsu Tomimatsu . In his introduction he mentioned x and + modes of waves and i have no idea what that is. My search tourned out some x and o modes, is this the same? I study physics in a different language so the confusion may be caused by that.

submitted by /u/maxdero
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How is the concept of Transfer of Training helpful in Psychology?

Posted: 09 Apr 2016 09:48 AM PDT