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Questions tagged [biology]

Questions about biology are OFF TOPIC and should be asked on the Biology Stack Exchange. However, questions about biology in the context of physics (e.g., biophysics) can be on topic here if the primary concern is physics.

58
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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?...
3
votes
2answers
297 views

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

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 ...
3
votes
1answer
62 views

probability density distribution: From free diffusion to presence of a barrier

I am a biologist and I am not very comfortable with statistical mechanics. However, I want to learn and I am trying to understand. I just need some clues from people that handle these topics easily. ...
0
votes
2answers
27 views

What is the optimal light setting for human vision? In other words, is my vision better during the day or at night?

There seems to me to be two main effects that should be considered in answering this question. The first is that the iris dilates in low-light settings, which causes an increase in the numerical ...
2
votes
1answer
1k views

How many calories in a block of wood?

I was recently thinking about the human body and the energy we get from food. I understand we don't have the ability to properly digest certain things like stones and wood and grass, but if we did, I ...
0
votes
1answer
80 views

Why universe is so perfectly made for us? [duplicate]

I am very eager to learn that, "Why universe is so perfectly made for us?" Or our universe is just stable by chance?
-1
votes
1answer
43 views

Same amount of calories burned for half the reps and double the weight? [duplicate]

So I was looking at the work= force x distance equation and was just wondering if for example I normally do 100 dead lifts at 100 pounds. Would I get the same calories burned if I did 50 dead lifts ...
4
votes
0answers
65 views

Has anyone ever actually considered a spherical cow? [closed]

Yes, I'm aware this question is somewhat whimsical. I'm sure every physicist is familiar with "Consider a Spherical cow". Has a cow (or any animal for that matter) ever been assumed spherical for ...
-2
votes
2answers
51 views

What if the luminosity of Sunlight increased by 10% [closed]

If the luminosity of sunlight increased by 10%, would people be able to survive outside? Would such brightness of light be very harmful to them, for exemple as much as the Mercury Vapour Lamp without ...
41
votes
3answers
7k views

Can ants walk on liquid mercury? [closed]

I'm not a physicist, but I was wondering: Can ants walk on dense liquid like mercury and why?
-2
votes
1answer
137 views

Freeman Dyson: Advanced intelligences thinking in an expanding universe [closed]

I dont know if this is the correct place to ask this, because is highly speculative and maybe even hard scifi. But... I think is less speculative than the many worlds interpretation of QM or many ...
1
vote
2answers
328 views

Is the universe really “fine-tuned for life”?

I understand what is meant when we say the universe is "fine tuned", but I've seen it claimed it's is fine tuned "for life". Is it? When I look at known or even speculated life in our universe, I see ...
2
votes
3answers
82 views

What is the relationship between the amount of radioactive substance and the harm it does to the body?

This is probably a very simple question, but I wonder how the amount of radioactive substance is related to the radiation it emits and therefore the harm it does to the body. If I held 0.1g of barium-...
0
votes
0answers
99 views

How do hypermetropic people see objects beyond the focus of their convex corrective lenses?

The way I have developed intuition about optics suggests that humans can only see objects if two rays of light that originally emanated from the same point reach the eye in a way such that when ...
1
vote
0answers
103 views

Why are there limits on physics' applicability? [closed]

(Not sure if this is the right SE for this question). Physics is great at predicting what inanimate stuff do. Why can't it also predict what living things do? For example, if I throw a ball off a ...
0
votes
0answers
51 views

Why animal eyes see the spectrum from red to violet?

Maybe this would not be proper question on physics stack exchange, but it originated from physics book so I'll post it here anyway. I have much interest in color recognition evolution. I'm studying ...
1
vote
2answers
74 views

If you are ontop of a giant heavy object that is falling from the sky, is it possible to jump and roll at the perfect time to survive? [duplicate]

I don't know if gravity or the speed of the drop would prevent us from jumping, but would something like this be possible? If it's not possible on the ground, is it possible in the ocean? I'm sorry ...
14
votes
2answers
589 views

Implications of parity violation for molecular biology

In biology, the concept of parity emerges in the context of chiral molecules, where two molecules exist with the same structure but opposite parity. Interestingly, one enantiomer often strongly ...
3
votes
1answer
82 views

Internet - mobile phone vs wifi

wifi cost me like 30USD while mobile internet 10USD, I thought to save this monthly bill by purchasing a mobile-phone-router. The only thing that blocks me from that is radiation. I'm far fetched ...
1
vote
1answer
85 views

Why has it taken so long for people to talk about using Far-UVC light for disinfecting?

If you don't know what I am referring to you can see this simple TED talk https://www.youtube.com/watch?v=YATYsgi3e5A. There are also many articles online about it. After watching that TED talk, all ...
1
vote
3answers
168 views

Why can I see the glow from my TV remote's LED if it is supposed to emit in the infrared?

The TV remote light emissions being >700nm are supposed to be invisible right? Same goes for proximity sensor on phone and laser focus on phone's back camera. But how could, me and 3 more people I ...
1
vote
2answers
319 views

Thermal Radiation of human body

I've read that all bodies emit electromagnetic radiation of all wavelengths. Does this mean that humans emit gamma rays too (excluding the radiation from radionuclides present in humans)?
2
votes
2answers
43 views

What is the enviroment in which water will come out of an ice fishing hole?

I have watched some videos on YouTube of people cutting holes in ice and water not just finding equilibrium in the hole, but water actually coming out of the hole along with many fish. There has to be ...
0
votes
1answer
120 views

How dangerous is a neutrino experiment near human habitation? [duplicate]

I just read about people trying to capture neutrinos and study them. America has a lab in Antarctica and France deep under the ocean. Is it dangerous to conduct such an experiment where people live or ...
-1
votes
1answer
353 views

Does Square Cube Law always hold? [closed]

There is a video that has been doing the round for a few years of an MIT lecture that has become a topic of debate in another forum I am a member of. The lecture by Prof Walter HG Lewin discusses ...
1
vote
1answer
73 views

How much energy burned during human walking exercise? [closed]

Let's assume that a person walks on a flat surface. Work performed by a human can be calculated by this equation: $W=F*s(1)$, where $F$ is a force and $s$ is a distance. I am curious how mobile ...
1
vote
1answer
88 views

Understanding the color of fluorescent and non-fluorescent objects

I am trying to read up and understand a lot about how normal looking objects like chairs are visible to us as compared to fluorescent substances. This question says that - "It is often said that ...
1
vote
2answers
129 views

Neutrino project in Tamil-Nadu India [closed]

In Tamil-Nadu, the Indian government is going to start a neutrino project. Questions: Is it harmful for people who stay there? Will this project affect any living beings? Does it cause any ...
0
votes
2answers
84 views

Why does yawning distort headphone music?

During deep and prolonged yawning, I noticed the music tonality is distorted: the pitch becomes slightly lower. Why?
4
votes
1answer
88 views

Are there examples of history dependent quantum dynamics that evolve like biological life?

There are examples of time evolution of quantum dynamics with history dependence, such as these quantum random walk examples which make use of a memory parameter to influence the distribution of the ...
1
vote
0answers
317 views

Is it possible to prove that an elephant and a human could jump to the same height? [duplicate]

Is there a physics argument, based on scaling, that leads to the conclusion that an elephant and a human could jump about same height? Could this be extended to any two creatures with different ...
0
votes
0answers
28 views

When we push a wall, we get tired Why? [duplicate]

When we push a wall the wall does not move so, no work is done but still we get tired Why? What energy changes occur in this process.
0
votes
1answer
128 views

How long could someone survive in free fall? [closed]

If there was hypothetically a bottomless pit (no ground), then approximately how far down could you possibly survive without being killed by the speed? (there is no vacuum so air resistance matters.)
0
votes
2answers
75 views

Is 220 V, 50 A equally dangerous for a person as 1A, 11000 V? [duplicate]

The question is self-explanatory. I'm a high school student so feel free to use scientific terms.
0
votes
2answers
61 views

What do we call these energy forms?

First of all I apologize for the basic question. When we throw a ball upwards, energy gets converted from us to kinetic energy which becomes potential energy and as the ball falls back down it ...
6
votes
2answers
568 views

Is my tritium keychain emitting significant amounts of radiation?

I recently purchased a tritium keychain, composed of a small glass vial of tritium gas partially enclosed in a stainless steel fob. Here are the Amazon links so you can see a specific example: Link ...
0
votes
1answer
36 views

Getting a positively charged magnet close to the brain [closed]

Simple and weird question that keeps going around my mind: If I put a positively charged magnet close to my head, shouldn't it interfere with the electric charges going through my neurons in my brain? ...
2
votes
0answers
152 views

What do the planets in our solar system smell like? [closed]

For example, if Jupiter is mostly hydrogen and and helium, but has ammonia clouds, does that mean it smells like a cat's litterbox? Does Mars smell like iron? Asking in order to give kids a more "...
2
votes
2answers
109 views

Why are people dark skinned in hotter areas despite dark colour absorbing the most heat? [closed]

I’m not sure if the reason is in the field of biology or more towards physics but as my reasoning is based on the physics part being that perfectly black bodies are perfect absorbers of heat and light ...
2
votes
1answer
94 views

What would happen if the aqueous and vitreous humour of a human's eye are replaced by some harmless transparent liquid of different refractive index?

The title says it all. What would the person be able to see? Note By harmless, I mean that it is non-corrosive, non-toxic, etc. The liquid doesn't cause any biological damage to the eye or any other ...
1
vote
4answers
4k views

Running or walking up stairs = same work?

I have a question belonging to the picture below. It is mentioned that whether you walk up or run up stairs the same work is done. When work equals (force in the moving direction) times the way, ...
2
votes
1answer
84 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 ...
0
votes
0answers
202 views

Can a human body actually experience large gravitational time dilation?

As sometimes depicted in science fiction, can a human actually experience a large gravitational time dilation? These depictions often show a human experiencing a large dilation (ex. 1 minute = 10 ...
0
votes
1answer
221 views

Physics of Sound and the middle ear?

Once sound waves reach the eardrum, ,the eardrum moves back and forth and transmits those waves/pulses to three bones that serve to transmit and amplify the pulses to another "drum" in the inner ear. ...
15
votes
4answers
520 views

On what specific astronomical observations is the Fermi paradox based?

This is a question about the Fermi paradox, a topic that can attract a lot of opinions. However, the scope of this question is strictly limited to a specific factual topic, and I've edited it quite ...
0
votes
1answer
147 views

How can cats survive a 32 floor fall? [closed]

There have been instances where cats fall from more than 30 stories high, yet escape alive! The record was a cat which fell 32 floors, yet only suffered only slight damage to its body and lost a ...
3
votes
1answer
56 views

What would the ideal amount of gravity be for an Olympic sprinter?

The goal here is to get the sprinter running as fast as possible. How much of an effect would more or less gravity have on the top speed of an Olympic sprinter, say... Usain Bolt? 6 ft 5 in (1.95m) ...
4
votes
1answer
1k views

Can humans hear transverse sound waves?

According to Wikipedia and validated by a clever thought experiment here, sound waves can be transverse as well as longitudinal, if they're propagating through a solid. Consider my mind blown and my ...
0
votes
2answers
75 views

What is the difference between the way the brain sends signals as opposed to how an electronic device sends signals? [closed]

As I understand it, a brain communicates through sending signals via ions and chemical reactions resulting in concentrations of ions, a computer sends signals by electrons. I'm really trying to do 3 ...
3
votes
0answers
171 views

What happens to your pulse rate when you are in zero gravity in space? [closed]

I am new to stack exchange, this is my first post. To start with, what happens to your blood pulse rate when you are in zero gravity? Does it increase or decrease? I thought a lot about this but am ...