Questions tagged [perception]

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32 views

Why does the wind close doors?

Assume you have two rooms, both with holes in the wall (more commonly known as open windows), which connect each room to the exterior. The two rooms are connected, but the connection can be closed by ...
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45 views

How to explain this thumb experiment?

Close your thumb to your eyes and align your eyes, thumb and moon. Then focus your eyes on your thumb and watch the moon behind your thumb. You will find that the moon becomes small! Remove your thumb ...
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5answers
5k views

Why don't humans perceive sound waves as twice the frequency they are?

I was reading about how at how acoustic beats work. If we combine two waves with frequencies $f_1$ and $f_2$ and unit amplitude, their combination is $$ \begin{align} A &= \cos\left(2\pi f_1x\...
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2answers
148 views

Why does the additive color model use red, green and blue instead of yellow, green and violet?

Long cone cells in the human eye are most sensitive to 570-nm wavelengths which are more like spectral "yellow" than spectral "red" and short cone cells are more to 440-nm wavelengths which are more ...
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28 views

Red and orange lights appear to be blinking [closed]

Why does the red and orange lights appear to be "blinking" and the blue and green lights appear to be still? The lights on this hula hoop are always stagnant, and in every picture this exact same ...
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2answers
52 views

Perception of time [duplicate]

A video I came across in youtube recently had mentioned how Einstein perceived time. It said he thought of all moments, the present, past and future to exist together and how it is not like one ...
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3answers
797 views

Why do we perceive time?

Since everything (at least what we observe) is travelling through the time in the same direction and speed why do we even perceive the time? Of course, there is the time dilatation, but it is ...
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180 views

Building the Penrose Unilluminable Room [closed]

As an architect with an interest in the natural sciences I was intrigued when I first learned of the illumination problem and its proposed solutions, specifically the one proposed by Roger Penrose in ...
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0answers
22 views

Visualizing higher dimension [duplicate]

Why can't we visualize Higher dimensions greater than 3? Is it just because the dimensions doesn't exist (Certainly I know that space-time is four dimensional) or any other physical reasons.
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3answers
111 views

What had Feynman meant when he told nobody understands Quantum mechanics? What do we mean by understanding Quantum mechanics?

What had Feynman meant when he told nobody understands Quantum mechanics? What do we mean by understanding Quantum mechanics?
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2answers
62 views

Why do we see things upside-down when we’re upside-down but not a camera?

If I do a handstand, everything looks upside down (which is originally what we see if we’re upright but the brain switches this). I assume this is because the change in how light rays enter our eye. ...
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3answers
72 views

Virtual images - Work of a brain or work of a lens?

I am just a high school student trying to self study, so please excuse me if this question sounds silly to you. Many people tell me that virtual images are formed when two rays that are diverging ...
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2answers
179 views

Human perception of temperature

I had the following thought experiment recently: Suppose we have a vibrating plate for which we can tune the amplitude and frequency of vibration, and imagine we hold a finger against the plate. For ...
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29 views

The rise of BCI

If EEG and MEG are measuring different aspects of neural oscillations, why can't we measure the combined signals as a whole, when we are doing the same for higher frequencies? Why did the us navy ...
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1answer
161 views

Why hot soup is tastier than cold soup? [closed]

My physics teacher recently asked me this question. Can anyone answer the question?
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1answer
93 views

What is this optical illusion in which airplane propellers appear to rotate backwards? How is it explained? [duplicate]

This airplane's propellers are both rotating anti-clockwise. But as you see, they are seem like rotating clockwise seen from front (nose) side. This phenomenon is known as optical illusion. My ...
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1answer
68 views

Does intuition really matter in the beginning of any new physics course? [closed]

Encountering some new courses like quantum mechanics, theoretical solid state physics and some other courses made me feel dumber than I ever felt.  Basically, I'm that kind of students who hate to ...
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1answer
27 views

Feeling sound; frequency and volume

How loud and "low" must a sound be in order for one to feel some physical sensation in response? I've read that below certain frequencies humans can be expected to "feel" sounds in their chests, and I ...
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1answer
36 views

How do we hear harmonics and how does it affect audio fidelity?

First and foremost, do we hear a sound wave as a sum of all the individual harmonics, at the fundamental frequency, or do we hear all the associated harmonics above the fundamental frequency and ...
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1answer
410 views

Why don't we see inverted image while wearing spectacles? [closed]

We know that the lens in our eyes forms an inverted image on retina and brain reverses it to give the correct image. But when one wears specs the image would get reversed twice so we should see things ...
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5answers
7k views

Why can we distinguish different pitches in a chord but not different hues of light?

In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together ...
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1answer
157 views

How does the Many-Worlds Interpretation of Quantum Physics relate to Consciousness? [closed]

According to the Many-Worlds Interpretation of Quantum Mechanics, each quantum event causes the world to "branch" into a superposition of outcomes. How come "my" consciousness only chooses one of ...
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2answers
161 views

Why does physics “make sense”? [closed]

I was wondering if anybody had an explanation for why physics makes so much sense to us humans. In physics, many concepts just seem to make sense to me, but I cannot explain why. You may say that this ...
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2answers
215 views

How many eyes are needed to see a four-dimensional world? [closed]

If a four-dimensional world were to exist, how many eyes would a creature minimally need to see it (in three dimensions)? Three? Four? (Bonus question: how should these eyes be spatially configured?)...
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1answer
42 views

EM spectrum and sense of sight

If we cant see all the spectrum does this mean that maybe exist objects we cant perceive? or it just the colors we cant perceive?
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2answers
54 views

Perception of curvature of human eye [closed]

How are human eyes able to detect the different curvatures of surface ? Basically how are the human eyes able to differentiate between a plane surface and a convex or a concave surface?
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6answers
9k views

How does light combine to make new colours?

In computer science, we reference colours using the RGB system and TVs have pixels which consist of groups of red, green and blue lines which turn on and off to create colours. But how does this work?...
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2answers
419 views

Why might Roger Penrose argue that Godel's incompleteness theorem(s) suggest that consciousness is non-algorithmic? [closed]

This past March, when I called Penrose in Oxford, he explained that his interest in consciousness goes back to his discovery of Gödel’s incompleteness theorem while he was a graduate student at ...
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1answer
64 views

Why can't our cognitive sense or five senses sense or fathom hyper-dimensional spaces? [duplicate]

Why can't our cognitive sense or five senses sense hyper-dimensional spaces? Is it because of the way our human body is built?
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1answer
130 views

Why do I see discrete images when moving an object in front of a screen? [closed]

I observed this while doing my homework. I have a habit of shaking my pen between my fingers vigorously while thinking something. My PC's screen is right in front of me (on my study table itself). ...
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2answers
102 views

Tiny blue and red paint close to each other result in black or magenta? [closed]

Now, if I draw two tiny spots with red and blue paint on paper and they are so close (but they do not cover each other) to each other that human eyes cannot identify there are two spots. To the color ...
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1answer
150 views

How is the subjective loudness of sound computed?

The intensity of a sound is a measure of the energy that the sound waves carries through space per unit time per unit area (since energy is conserved along the wave unless work is done on/by it and ...
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1answer
81 views

Why are the active noise cancellation headphones subjectively better in reducing “periodic” noise?

According to experience of mine and of my friends using active noise cancellation headphones, the technology is much more efficient in reducing "periodic" noise, such as humming of jet engine, fridge ...
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1answer
69 views

Why we see a static picture of the sea when we are traveling by plane?

This question may look stupid but it's something that came to my mind months ago when I was on a plane. When one looks through the window on a plane, there are light and dark parts of the ocean (it's ...
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0answers
36 views

How can we determine time flows in one direction? [duplicate]

Suppose that time could flow in either direction, forward or reverse, similar to a movie. How could our brain possibly record that time had moved backwards? Would there be any way to tell if time had ...
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1answer
567 views

Do we hear anything special when the beat frequency is in audible range, but the sounds producing the beats are not? [duplicate]

When the beat frequency is very low, we hear periodic maxima and minima. Our ear cannot perceive a on-off like sound when its frequency is more than 10 Hz. So, beat frequency in audible range will not ...
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0answers
57 views

What causes observed color differences in white LED's for near and far fields?

While running towards traffic early morning before sunrise I recently noticed that the new automobile LED (white) lights when viewed at a distance appear blueish, but when the light is viewed much ...
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1answer
232 views

Why do we experience a slice of time, but not a slice of space? [closed]

I (and every one I guess) perceive space as an extended region where things happen. In contrast, time is perceived as a lucky of slice. Also in space I can choose in which direction I want to move, ...
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1answer
93 views

Why doesn't the brain flip retinal image horizontally as well?

I was reading about the Camera Obscura and the physics of apertures, and I read that "The camera obscura produces a flipped (horizontally) image as well as an inverted (vertically) one." I understand ...
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3answers
102 views

What is Fourth Dimension?

Before people get pissed at me for asking a question that has likely been asked more than a few times, I just want to know a simple answer, if first dimension is that an object exists, (collision) ...
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2answers
84 views

Defocusing the eye and computer monitors

Im not sure whether this is the right site to post this on, but here goes : We are often told to relax our eyes when using computer/tv screens for extended periods of time. I often find that I forget ...
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2answers
143 views

How to define white color scientifically? [duplicate]

I'm sorry some of you may mark this question as duplicate, but even though I searched over about this I couldn't get satisfacory answer. Also I think this question is more related to biology, but I ...
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2answers
504 views

Why does the moon appear fairly flat to a naked eye?

When I look at the regular ball picture the "edges" appear somewhat darker. Here's a random image I just found on image search :) Image source and that's how I can tell it's "round". Or so I assume. ...
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1answer
112 views

Is visible light really visible? [closed]

As we know, colors only exist in the brain. How can we see light if it has no color? Our eyes detect light, but seeing occurs in the visual cortex. Is visible light really visible?
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1answer
404 views

How can a loud sound's perceived pitch differ from its predicted value from only its frequency?

Sparknotes $\qquad $ Quora answer by Mr. Kennan Hye BS (Engineering), MEng. (Acoustics): Pitch is sometimes defined as the fundamental frequency of a sound wave (i.e. generally, the lowest ...
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1answer
72 views

What limits the electromagnetic radiation we can see? wavelength or frequency?

Can we only see electromagnetic radiation that has certain range of frequencies and a certain range of wavelengths?
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3answers
119 views

Travelling at a speed faster than light [closed]

Imagine yourself to be bat. You cant see anything. You don't have eyes. All you can do is echolocate, using ultrasound. Now imagine something is moving away from you faster than the speed of sound. ...
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3answers
313 views

How does the human ear guess the source of the sound?

Suppose a sound is produced behind you. You can easily tell that the sound came from behind. Our ear lobes face towards the front and hence traps the sound waves which come from the front. Yet, we ...
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2answers
51 views

If someone were to put really small objects 10x spaced on a background, would they see the objects or the background?

If someone were to put a sheet full of 1 micron x 1 micron black squares as a grid on a white piece of paper, and spaced them 10 microns apart (up-down, left-right, obviously diagonal doesn't count), ...
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3answers
4k views

Why does the Sun appear larger during the sunrise and sunset?

Why does the Sun appear larger during sunrise and sunset compared to its size during midday even though its distance from the Earth remains fixed all the day? It is only during the Winter when the Sun ...