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Tuesday, January 30, 2018

During sperm production, what is the mechanism which guarantees that half of produced sperm have an X chromosome and half have a Y chromosome? In other words, why are 50% of us male and 50% of us female?

During sperm production, what is the mechanism which guarantees that half of produced sperm have an X chromosome and half have a Y chromosome? In other words, why are 50% of us male and 50% of us female?


During sperm production, what is the mechanism which guarantees that half of produced sperm have an X chromosome and half have a Y chromosome? In other words, why are 50% of us male and 50% of us female?

Posted: 29 Jan 2018 08:24 PM PST

Do deep sea ecosystems follow the normal seasons?

Posted: 29 Jan 2018 05:46 PM PST

Do ecosystems at say the bottom of ocean trenches feel the same changes as the surface or are they mostly constant being so far from the surface?

submitted by /u/Rockysmk
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Why does helium make voice higher pitched if source frequency remains the same?

Posted: 29 Jan 2018 07:15 PM PST

I know sound moves faster in helium, but I don't see why frequency should be any different if the source vibration is the same as it is in air.

(eg). Say in air, sound speed is R m/s, and there is a vibration at 1 Hz.

Vibration starts at t=0. Vibration just started, so distance moved is 0 meters.

After 1 second, t= 1, so vibration has moved R(1) = R meters.

When t=1, second vibration starts. This distance traveled is 0.

Well, because both vibrations move at the same speed, the distance between the first and second vibrations (and 3rd, 4th, etc) is always R meters. And since vibration travels at R m/s, there is a 1 second gap at the receiving end between each vibration.

So how does sound speed affect frequency?

submitted by /u/yosimba2000
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What’s the difference between clinical depression and regular unhappiness?

Posted: 29 Jan 2018 03:29 PM PST

Do rubber soles on our shoes actually protect us from lightning strikes?

Posted: 30 Jan 2018 01:53 AM PST

Why must therapeutic proteins be stored at 2-8°C to prevent them from degradation and denaturation when proteins in our body are in an environment that's 37°C and are perfectly fine?

Posted: 30 Jan 2018 02:29 AM PST

What happens exactly with the stability of therapeutic proteins when kept at room temperature?

submitted by /u/opulousss
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Why doesn't aluminium fuse directly to copper? What determines the kinds of metals that can be fused or amalgamated among each other?

Posted: 29 Jan 2018 05:53 PM PST

Hey there kind scholars!

My girlfriend and I have a strange habit of watching old episodes of that Discovery channel show, "How it's made", to relax and sleep. Last night we watched one episode on "Thermal machines" (such as air conditioning units and refrigerators). On a certain moment during the fabrication of the air conditioner, the narrator said that a certain piece of the aluminium "net" component had to be welded to copper using a zinc-aluminium alloy.

The question(s) then is (are):

Why can't the copper and aluminium be welded directly?

What characteristic on a metal determines it to be able to be welded or amalgamated to another?

Edit 1: a comma.

submitted by /u/lewdlou
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Why can’t you take a pulse with your thumb?

Posted: 29 Jan 2018 07:55 PM PST

I've been told that your thumb 'has its own pulse' but I don't understand how that would work could someone please explain?

submitted by /u/bbroomhead
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When you look at your reflection on the inside of a metal spoon it appears upside down, why is this so?

Posted: 29 Jan 2018 07:13 PM PST

If you are listening to music on your device on mute, does the device still process the sound files, or does it only keep track of the time?

Posted: 29 Jan 2018 02:59 PM PST

How are raw alpha particles and electrons collected for use in experiments?

Posted: 29 Jan 2018 10:26 PM PST

In a physics class, our class discussed famous experiments such as Rutherford's Scattering experiment, in which alpha particles were sent into gold foil, deflecting off. How did scientists back in the 1900s (or even now) collect these raw particles for usage?

submitted by /u/ShayminKeldeo421
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How do we solve problems that don't have constant acceleration?

Posted: 29 Jan 2018 10:58 AM PST

I understand basic physics and how we solve motion problems using kinematic equations, but these all rely on a constant acceleration. How do we solve problems where this isn't the case, such as a rocket leaving Earth's gravity(since acceleration due to gravity gets smaller the further away you are).

submitted by /u/zakerytclarke
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Why do people turn pale when they are frightened or see something shocking?

Posted: 29 Jan 2018 01:00 PM PST

[rocket engineering] Ice as rocket fuel ?

Posted: 30 Jan 2018 02:06 AM PST

So, my knowledge of rocket science is basically on the level of "avid Kerbal Space Program player". I understand concepts like Delta-V and TWR. So onto my question. As ice defrosts it becomes liquid and then gas. Now water is a bit of a problem here since it actually gets less dense as a solid, but most things it's the other way around. So picture a tank full of some frozen substance, with a nozzle on the end. As it defrosts and evaporates it builds up pressure, expelling some of the gas out the nozzle - and you have a rocket engine. Since space is cold, you may want to use an electric heater to get it going - much like Ion engines are driven by electricity though I know that electric heating is rather more energy hungry. Of course if the substance in question has an evaporation point above the average temperature of space (to the extent that "temperature" makes sense in a near vaccuum) you may not even need that (at least, closer to the sun).

Would such a rocket be viable at all ? How would it compare to say - a xenon Ion engine like we already use ? What substances would make the best candidates for an ice fuel in terms of ISP, delta-V for the weight, energy required to melt it and viability of working with the substance ? Frozen CO2 [dry ice] has been proposed as a generator-driver for Martian colonies - would it be a good candidate ?

I'm under no illusions that I've stumbled onto a rocket design that the best engineers at NASA and SpaceX have somehow overlooked - I'm just curious about how the idea would work in practise as a hypothetical and what sort of difficulties you could expect ? I see no viability at all for lifting rockets - so think in terms of vaccuum engines to use to accelerate your probe on it's way after you are already in space (much like Ion engines are used).

submitted by /u/metalpoetza
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Would a rainbow differ depending on the type of star or atmosphere?

Posted: 29 Jan 2018 09:55 AM PST

For example could there be a rainbow without Red or Green? Or a Rainbow that is completely blue... etc

submitted by /u/MarriedIntoTrashyFam
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If sound is just the travel of energy through the movement of air molecules, does a louder sound make air molecules move faster and thus increase the speed of sound?

Posted: 29 Jan 2018 05:53 PM PST

Can you have a stable binary planet orbit?

Posted: 29 Jan 2018 01:36 PM PST

I.e. Can two planets of similar size/mass orbit around a point in space between each other while that point orbits around the star of that solar system?

submitted by /u/cwood92
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What's the current state of research for nuclear power regarding efficiency and nuclear waste production?

Posted: 29 Jan 2018 05:21 PM PST

(heads up: I'm not very well familiar with advanced chemistry and physics, so I am looking for more of a layman's explanation!)

I live in Germany, where nuclear power is commonly not considered clean energy. This is mostly due to the extremly longliving toxic waste it produces. Therefor we have big political movements in Germany pushing for shutting down the nuclear power production all together. Thus (as far as I know) there hasn't been that much modernization going on over the past few decades.

A few years ago I read somewhere that nuclear power production today is far below it's potential and that modern scientific research is quite promising regarding the effiency (I think it said that were at ~10% of the potential effiency due to our lack of modernization) and waste production (I remember something about ways to reduce the radioactive waste to minimum of what is currently done). I also remember reading something about ways to recycle spent fuel to bascially use it up until it's gone and power plants that are basically failsafe.

Sadly I have no idea where I read this and I don't remember it looking very 'scientific' (iirc it was one of these pseudo-scientific looking inforgraphics).

So I was wondering if you could tell me what acutally would be possible if mankind was to decide to heavily invest in modernizing nuclear power production and what could be expected from further research. Are there known ways to get rid of dangerous radioactive waste? Or is this just the propaganda of the nuclear lobby, trying to convince people that renewable energy sources are not the absolutly best option for the future?

submitted by /u/uberjack
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How do we estimate the number of people on Earth?

Posted: 29 Jan 2018 02:31 PM PST

Why do we find marine and land organisms buried together?

Posted: 29 Jan 2018 03:11 PM PST

I've been wondering this as I've heard this claim from numerous sources and I just wanted to know, why do we see this?

submitted by /u/123456fsssf
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How exactly does the immune system ward off external parasites?

Posted: 29 Jan 2018 12:57 PM PST

My curiosity was piqued by reading about mange in dogs, specifically quotes from this page about how a healthy immune system keeps mites under control:

Demodectic mange most often occurs when a dog has an immature immune system, allowing the number of skin mites to increase rapidly.

Source: https://vcahospitals.com/know-your-pet/mange-demodectic-in-dogs

Since mites are outside of the body and presumably too large for white blood cells or the typical immune system defense against e.g. bacteria anyway, by what mechanism exactly would it be affecting their reproduction?

submitted by /u/unthused
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Why is this year's flu vaccine so bad?

Posted: 29 Jan 2018 12:28 PM PST

How does your finger print grow back after you peel your skin away?

Posted: 29 Jan 2018 10:15 AM PST

Just curious because I peeled it too far and it's kinda growing back

submitted by /u/kylethe_techguy
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Monday, January 29, 2018

How do we know what Ancient Egyptian (or any ancient language) sounded like? How accurate are names like “Osiris” and “Tutankhamen” to what they actually sounded like when spoken by Ancient Egyptians?

How do we know what Ancient Egyptian (or any ancient language) sounded like? How accurate are names like “Osiris” and “Tutankhamen” to what they actually sounded like when spoken by Ancient Egyptians?


How do we know what Ancient Egyptian (or any ancient language) sounded like? How accurate are names like “Osiris” and “Tutankhamen” to what they actually sounded like when spoken by Ancient Egyptians?

Posted: 29 Jan 2018 03:21 AM PST

Egyptian is just an example in this question, and this can apply to Ancient Mayan mythology, or pretty much any ancient religion/society

This has always confused me. Where do our anglicanized names like these come from and how confident are we that this is what these historical and mythological figures were called by ancient peoples?

submitted by /u/okteej
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Why do we have a depression in our skin above our upper lip? Does this have any significant purpose?

Posted: 28 Jan 2018 06:45 PM PST

Is Current Audio Amplification Technology at the Limits of Physics?

Posted: 29 Jan 2018 02:55 AM PST

I'm a full-time busker and have been wondering about the physics behind audio amplification and speakers lately. I currently carry about 15kg (20 if you count the guitar) worth of battery-powered PA equipment around and even with that weight, the amplification reaches to about only 50 people in an open venue.

I am wondering if speaker/amplification technology has hit a ceiling when it comes to efficiency and weight relative to dispersion and volume? Should we be looking forward to a future when we can use 5kg worth of amplifying equipment to reach a crowd of hundreds or is that just plain physically impossible?

Thanks!

submitted by /u/emorcen
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Why light doesn't lose speed when affected by gravity?

Posted: 29 Jan 2018 04:43 AM PST

I know it changes frecuency, but it sounds like an exception to the rule.

submitted by /u/Makaan1992
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When you wash your skin with lukewarm or hot water after you’ve been in freezing temperatures, why does it feel like the skin is burning? Is your body actually in danger or are the nerves misinterpreting what is happening? Are there other examples of this situation?

Posted: 28 Jan 2018 05:39 PM PST

Have scientists found any meteorites with a substantial concentration of precious metals?

Posted: 28 Jan 2018 10:55 PM PST

I've read that in the distant future asteroid mining will be a big deal. I'm wondering that if there is lots of gold and other precious metals to be found in the asteroids then have people already found meteorites that have gold in them?

submitted by /u/LolaAbbot
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Do birth control pills affect attraction/mate-choice?

Posted: 28 Jan 2018 05:52 PM PST

I read something that said that birth control pills affect a womens attraction. Specifically that women will choose lower testosterone males who are more genetically similar to them on the pill.

If they come off the pill they will become more attracted to higher testosterone and more masculine men.

Im wondering about how reliable these studies are? Is it enough to conclude that there is a definite link? Are the sample sizes large enough?

If its true it could have a large impact on long term relationships or marriages

submitted by /u/bcserver
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Why does the human brain contain folds? Are they indicative of something else?

Posted: 29 Jan 2018 03:59 AM PST

Does the earth take up less space during an ice-age due to thermal expansion?

Posted: 28 Jan 2018 08:21 PM PST

What does the body do with all that extra keratin protein when someone goes bald?

Posted: 28 Jan 2018 02:02 PM PST

Why don't anti body's protect you from flu season?

Posted: 29 Jan 2018 06:19 AM PST

Why is it itchy on the elastic part of the socks, bra etc.?

Posted: 28 Jan 2018 03:52 PM PST

How does an animal with static camoflauge know where to hide?

Posted: 28 Jan 2018 11:56 PM PST

For example: how does a leaf-tail gecko know that it is hiding on the correct tree bark?

submitted by /u/Jellyjellybean01
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How often do the planets of our solar system have the same exact alignment?

Posted: 28 Jan 2018 11:34 PM PST

For example, when was the last time all the planets were in the exact same position that they are in today?

submitted by /u/JuanElGhoul
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Why is the milkyway galaxy depicted as having a bright center, if we really have a huge blackhole?

Posted: 29 Jan 2018 05:20 AM PST

I know there's a huge blackhole in the center of the milkyway, but was wondering why the milkyway Galaxy is frequently depicted as having a bright white center. Thanks!

submitted by /u/DerpTheKing
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Why are Ramsey Numbers so difficult to find and would finding an efficient algorithm for finding Ramsey Numbers have any benefit for mathematics in general?

Posted: 28 Jan 2018 11:19 PM PST

I was looking at Ramsey's Theorem (from which the party problem was created) and was surprised to realize that the Ramsey Number for (5,5) is still currently unknown. This problem at first seems deceptively simple.

1) Is an efficient algorithm possible to find Ramsey numbers?

2) Would finding such an algorithm be a "big deal" for mathematics?

3) Would a quantum computer be more useful than a classical one for this type of problem?

submitted by /u/Stuck_In_the_Matrix
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In Planet Earth, the Okavango Plains are flooded from rains that happened 5 months ago in the Angoland highlands. How much water fell in order to still be able to create a water-based paradise? How did it not all evaporate/get used by animals, plants, etc?

Posted: 28 Jan 2018 06:17 PM PST

If a flu shot has a certain percentage of effectiveness, does that mean it is more effective against some of the strains than others?

Posted: 28 Jan 2018 04:17 PM PST

So in the current epidemic, if the flu shot is 40% effective, what is the actual effectiveness against the worst strain? And how does that effectiveness play out? More effective against a smaller exposure to the virus, or having more to do with the health and age of the infected?

submitted by /u/texlorax
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Psychedelic drugs are now in the spotlight due to their therapeutic uses. Alcohol is often eschewed for its negative effects. Are there any known therapeutic uses for alcohol that can result in positive psychological changes over time?

Posted: 28 Jan 2018 04:32 PM PST

If I was floating in space and only needed to maintain my body temperature to survive, how far from the sun would I need to be to maintain a stable safe bodily temperature?

Posted: 28 Jan 2018 09:33 AM PST

Why are alkane gases like propane so flammable considering that they are non-polar compounds?

Posted: 28 Jan 2018 02:09 PM PST

Does the body actually absorb all of the vitamins in a supplement?

Posted: 28 Jan 2018 10:37 PM PST

I started taking a multivitamin. The label has more than the daily recommended values for most of the vitamins in it. If we did absorb and purpose the whole amount, wouldn't we have a toxicity risk?

submitted by /u/KReese6
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What is the biological purpose of having an allergy? I don't see how it can possibly benefit an organism.

Posted: 28 Jan 2018 10:30 PM PST

Sunday, January 28, 2018

How did early chemists isolate the earliest identified elements and determine that they were in fact elements?

How did early chemists isolate the earliest identified elements and determine that they were in fact elements?


How did early chemists isolate the earliest identified elements and determine that they were in fact elements?

Posted: 27 Jan 2018 07:55 PM PST

I've been trying to read as much about this as I can on Wikipedia but I haven't seen on there yet an answer to this question. In the article on the History of Chemistry, it mentions that Jabir ibn Hayyan identified mercury and sulfur as chemical elements but doesn't indicate how he actually figured this out. Whatever he did, it didn't seem to convince the scientific community of Europe (if they even knew about it) because in the article on sulfur it mentions that Antoine Lavoisier helped convince them that sulfur was in fact an element and not a compound. What did Lavoisier do to convince the scientific community of Europe that sulfur was an element and not a compound? What experiments did he run (if any) to do this? Both mercury and sulfur have been known since ancient times but other elements were only identified later, like nitrogen. How did people like Daniel Rutherford isolate nitrogen and how was it determined by scientists at the time that it was an element? I'm curious about this for all the elements, especially the ones discovered before the nucleus of the atom itself was discovered.

submitted by /u/DeutscherLerner
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Is extra muscle as hard on the heart as extra fat?

Posted: 28 Jan 2018 05:46 AM PST

Reading around I have seen suggestions that extra muscle can be as tough on the heart as carrying extra fat. This seems very unintuitive, I think of muscle as the good stuff and fat as bad (to an extent of course). But the logic is that muscle needs oxygen and nutrients and more of it strains the body. Is this true or just a myth?

submitted by /u/PunchTornado
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Why did scientists estimate the Opportunity Rover to only last for 90 days, and why did it last for that much longer (14 years)?

Posted: 27 Jan 2018 07:48 AM PST

Was it a miscalculation? Or a worse case scenario? What parameters are there for estimating the life span of a Rover?

Edit: Thanks to every single one of you who commented to get this question some traction :) And a big thanks to those who had an answer to it!

submitted by /u/Lenoxx97
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Does physical trauma (shaking/vibration/dropping) have an influence on batteries and how long they hold their charge?

Posted: 27 Jan 2018 04:01 PM PST

If I'm tossing my AA batteries around the house before I actually use them in something could I at all be shortening how long/well they can hold their charge?

submitted by /u/Ganja_Gorilla
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Thinking about the umbilical cord, at what point is it the mother's DNA and at what point is it the baby's DNA? Is there a point where they're mixed?

Posted: 28 Jan 2018 03:30 AM PST

Do the good bacteria in probiotic drinks and yogurts multiply as time passes? If so, does that mean we should wait as soo as possible before consuming them to get the most of it?

Posted: 28 Jan 2018 06:24 AM PST

Does the law of optics apply to non visable light?

Posted: 28 Jan 2018 06:36 AM PST

Question from the armchair here. Do higher wavelength telescopes have different resolution equations?

submitted by /u/Monoraffe
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How many dinosaur fossils are there compared to the original populations?

Posted: 28 Jan 2018 02:25 AM PST

When measuring the missing mass in the universe, how do we distinguish between black holes and dark matter since we can see neither?

Posted: 28 Jan 2018 07:15 AM PST

Is it true that the frontal cortex is not fully formed until age 25 in 100% of humans?

Posted: 27 Jan 2018 12:58 PM PST

I always hear the argument that people under 25 are not fully in control of themselves because "Their frontal cortex is not fully developed", as if they have an utter lack of executive control. I'm always wary of absolutes, and I have known plenty of people under the age of 25 who were far more mature than many adults. Is it an exaggeration, and/or do some people develop faster than others, or are there other factors at play other than frontal cortex development that has a hand in executive control and maturity? What's the story? I'd love some studies that prove this one way or the other.

submitted by /u/kuuzo
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If i do some heavy calculation on a CPU, producing a lot of heat, would the same amount of electrical energy produce the same amount of thermal energy as, say, a resistor?

Posted: 27 Jan 2018 11:27 PM PST

How do Scientists find out the molecular structure of a Substance?

Posted: 27 Jan 2018 09:45 PM PST

What’s the life cycle of a snail? Are they born with shells? Are their shells part of them that grows, like our fingernails?

Posted: 27 Jan 2018 01:52 PM PST

What determines the strength of a light?

Posted: 28 Jan 2018 04:52 AM PST

Are there any theories explaining why the northern hemisphere of Mars is uniformly lower in elevation than the southern hemisphere?

Posted: 27 Jan 2018 08:46 AM PST

For a map courtesy of NASA.

submitted by /u/Veritas-VosLiberabit
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What is the name for the 'average' spherical correction of an eyeglass if it has a cylindrical correction as well?

Posted: 28 Jan 2018 03:44 AM PST

I suppose SPH -5.00 CYL -1.00 on eyeglass prescriptions is equivalent to SPH -6.00 CYL +1.00, depending on using a plus or minus cylinder notation. 1 I would like to express the 'average' spherical correction as a single number, 5.50, to compare the spherical correction of a few friends. Does this 'average' value have an official name?

submitted by /u/Egmond
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How big does a body of water need to be to have noticeable tides?

Posted: 27 Jan 2018 01:16 PM PST

Does a planet create any kind of wake as it orbits it's star?

Posted: 27 Jan 2018 08:22 AM PST

What is the difference between Standard Model gauge coupling unification and the Supersymmetric one?

Posted: 27 Jan 2018 04:21 PM PST

Is the only difference in the GUT gauge coupling value or is the Weinberg mixing angle different as well?

P.S. I know there are vast differences even between the MSSM and the SM, I'm just asking for the gauge coupling unification.

submitted by /u/LabLadYT
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How do immune cells know not to attack beneficial bacteria in the body?

Posted: 27 Jan 2018 10:00 AM PST

How does a Seagull survive the winter without migration?

Posted: 27 Jan 2018 04:19 PM PST

Lately I've been seeing seagulls flying in the sky, despite being the dead cold of winter, with ice and snow everywhere.

What are the techniques do they use to survive the cold?

submitted by /u/Lishy1_5
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Does the repetition of a thought, out loud or internally, give rise to belief in that thought, regardless of whether it's true or not?

Posted: 27 Jan 2018 12:17 PM PST

For example, if I repeat "I'm the smartest man who ever lived," "It is raining in Prague right now," or "My girlfriend is at the store right now," is it possible that that thought gets embedded into your psyche and you end up believing it as a fact? This goes sort of along the vein of self help seminars that tell you to repeat "I am good," etc in a mirror everyday.

submitted by /u/lazylazy99
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