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.

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What determines the mathematical relations between energy use, axon thickness, and firing rate of action potentials in a neuron?

I have a naive model of action potential energy use and I’m unsure where the model is wrong. Clearly the model is wrong because its conclusion is wrong. When an action potential moves along an axon, ...
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Could I survive at (or near) absolute zero with a very, very, very thick sweater?

Imagine I'm in an infinitely large vacuum and have a special apparatus built into my body that allows me to breath, eat, pee/poo, etc. and never age. The vacuum is similar to deep space and has no ...
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Teaching Electromagetism to Life-Science Students

I am going to be teaching an introductory university class on E&M and Modern Physics (from Coulomb's Law through Maxwell's Equations and optics, followed by a brief mention of quantum and ...
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Force exerted by a muscle [closed]

You have a forearm in a horizontal position and from the forearm you pull a muscle in a vertical position 4 cm from the elbow. The hand holds a weight of 6 kg at 44 cm from the elbow and the weight of ...
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1answer
36 views

Has physics ever tried to explain how do we get “sensorial experiences”? [closed]

To be clear about what I mean with "sensorial experiences", let's take for example our visual experiences. Certainly, physics (and other sciences) explains a whole process which involves light ...
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Is 260 picoampere sufficient to transmit a signal through an axon in a nerve?

Would 260 picoampere be sufficient to transmit a signal through a 1 meter long axon in a nerve, with a diameter of one micron? There is context to why I ask this, but, because of failure to interpret ...
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42 views

Is evolution a violation of natural law? [duplicate]

According to the laws of nature progression is always downward. One of these laws is the Second Law of Thermodynamics which says that isolated systems cannot increase in complexity. For example, a ...
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2answers
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Why is it hard to exercise with wearing the mask? [closed]

In today with COVID 19, we should wear the mask all day. My teacher in Korean high school said "If you want to play basketball, you could play with wearing the mask" to me. My friends and I wanted to ...
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11answers
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Are colors grounded in physics or are they a matter of human perception? [duplicate]

My father was colorblind, and I always wondered if colors were a matter of physics or if different colors are just a human way of describing and differentiating our visual perception of the world? ...
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36 views

Using particle physics math model to simulate simplest life [duplicate]

We still don't know many thing going inside living cells so I'm wondering whether it's possible to create a math/computer model operating on basic known particles (or higher level composite particles ...
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10answers
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What determines whether colors you can't see are visible or not?

So, when someone is red-green colorblind, the colors appear the same to them, like this: And if you're totally colorblind, then things presumably just appear like they would in a black-and-white ...
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6answers
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Does bending your arm in space require any energy?

Since your are weightless in space, your arm has no weight, right? Does this mean that bending it in space requires no energy? Why or why not?
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Energy Conservation in Holding Weights [duplicate]

This is a two part question, and it might have to do with biology a bit. Part 1: I grab a heavy dumbbell and curl it. Halfway up I stop the curl and just hold it there with my elbow at 90 degrees. ...
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1answer
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Why do leaves of trees shudder when they expose to heavy smoke? [closed]

Why do leaves of trees shudder when they expose to heavy smoke? See this video here: https://i.imgur.com/hTOOxu6.mp4
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1answer
58 views

Is $200 \,\text{J}$ enough for heart defibrillation? [closed]

In some movie I saw that defibrillation was done on a patient by emitting $200 \,\text{J}$ electric impulse onto heart region. I couldn't in noway imagine is this quantity big or small, so I've tried ...
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2answers
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Can life decrease the entropy of an isolated system? [closed]

A high entropy isolated system is shuffling through its more probable micro-states. Local entropy dip produce several structures. These structures, akin to life, feed on free energy to preserve ...
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1answer
40 views

During pull-up, does your upper body use less energy when the legs are raised?

The pull-up mainly uses your biceps and your lats, which are exclusively upper body muscles. So would raising your legs during a pull-up reduces the energy used in those muscles? Let's say the energy ...
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1answer
45 views

Restart the Universe expansion? [closed]

Is there anything that could restart the universe expansion? Basically a black whole or something else entirely different? It seems to me that, once the Universe stops expanding, the human life ...
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1answer
48 views

High pressure cryonics

In this link, it is suggested to use high-pressure cryonics to freeze living cells, tissues or small organism as opposed to various and potentially toxic anti-freeze agent. The core idea is that over ...
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2answers
142 views

What does meant AC corona? Any connection to coronavirus? [closed]

In the abstract of this paper Authors said in abstract of that paper entitled Simulation of the AC corona phenomenon with experimental validation : ".....,This phenomenon is also associated with ...
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1answer
89 views

How can a picture of a virus be taken when they are not even 300 nm (wavelength of blue light) long?

We cannot take photos of protons because they are not at least the size of the wavelength that registers into visible light. I see photos of Coronavirus in the news everywhere where there is a clear ...
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0answers
41 views

Physics-based Demonstrations for biology students

I am looking for resources where physics concepts relevant to biology are explained in simple terms by actual experiments or virtual animations. The site should be suitable for freshman students with ...
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0answers
67 views

Is there a minimum principle which governs neuronal activity in brain function? [closed]

Reinforcement learning is a well established field which attempts to explain the behavior and decision-making of toddlers, among other agents. The core principle of this theory is based on dynamic ...
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2answers
44 views

Formation of Life on various planets

Is there any theory that suggests every creature (including bacteria and fungi) in our planet is formed by the atoms of our planet. If that is true, then is it possible that any other organisms will ...
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2answers
87 views

Is there any different model for universe which can create life?

I am an undergraduate student. I am not good at physics at all, but I interested to understand the physics. We know, our universe has four forces (there can be more than four) and some laws. And laws, ...
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2answers
63 views

The Calculation of work in different frames

Say there is a man running on a road. Friction is applying a force hence he is accelerating, but the friction is static hence does no work. We know that the change in kinetic energy is due to internal ...
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1answer
79 views

Effect of bluetooth headphones on health [closed]

There was an article on the internet assuming that there's a high chance that bluetooth headphones cause a lot of mental and physical damages to our body. They explained it in a pretty neat way if I ...
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2answers
66 views

Why is electrocution dangerous to humans and animals?

As far as I understand electric current is nothing more than the flow of electrons, that is, charge. So, my question is, what exactly happens when charge/electrons flow through our body and why is ...
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1answer
42 views

Understanding the relationship between $P=F/A$ in brain ventricles

Humans have a hollow space (see the colored part in the diagram below) inside our brain where cerebrospinal fluid is produced and circulated. A disease exists called "normal pressure hydrocephalus" ...
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Hyperspectral Imaging

Is it possible for a HSI camera to detect how long back a particular wound occured in the body? Eg: There's a body for postmortems with some marks/wounds at some places, can a HSI camera help us in ...
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1answer
90 views

Human colour perception – summary needed

I am a graphic designer and I really want to have knowledge about human colour perception but the longer I am looking for and the more I read the harder this topic seems to be. Physics is not my ...
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2answers
69 views

How can the energy be conserved, as negative work done on a moving body also wastes energy stored in my muscle? [closed]

Suppose a particle like object is moving on a frictionless surface. If I push it back to reduce its kinetic energy, it also wastes energy stored in my body. Is energy really conserved here? Again, ...
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2answers
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Bike Gears for maximum acceleration [closed]

What should the sizes of the gears on my bicycle be to achieve the highest acceleration possible?
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4answers
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Preventing fog inside snow goggles

I understand that goggles fog up because of a rapid temperature change. In other words, goggles that have been sitting on a table outside (i.e., are very cold), when you put them on your face which ...
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1answer
68 views

Spectral sensitivity of the human eye -

Following the question: Sensitivity of eye I would like to make sure what these % says about? Is it the ability to colour detection? The similar stuff is here: http://www.giangrandi.ch/optics/eye/...
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1answer
70 views

Banana vs Brazilian Nuts Radiation

Looking online I can find that the BED (Banana Equivalent Dose) is around 0.1uSv, but Brazilian Nuts can have up to 444Bq/kg. I know both of those foods are safe, I just wanted to understand how ...
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3answers
144 views

Why can't humans throw objects at bullet speed when the force involved seems so small?

The force that propels a bullet should at least be similar in intensity to the force experienced as recoil and the force exerted on the target. But these forces seem really low (the equivalent of a ...
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3answers
67 views

A single eye vision vs normal vision [closed]

I am trying to understand the basics of human vision and looking for a model to see pros and cons of a single eye vision vs two eyes vision. Generally my interest relates to a basic project in a ...
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6answers
7k views

Because things smell, is everything evaporating?

Everything, in theory, can have a smell, but that is not the whole point of this question. My main query is, since things do smell, does that mean that everything is slowly evaporating (or, ...
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3answers
75 views

Noise perception by humans - one vs two of the same noisy appliance - will the noise be “double”?

If I have a clothes washer in a room versus two of the same machine making the same noise, will the noise level be perceived by humans as twice the level it was before? I'm pretty sure sound is in a ...
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0answers
36 views

Could a planet experiencing tidal locking have a habitable area?

I wonder if it would be possible that, on a planet that always shows the same face towards the sun, there is a habitable area for some life-form similar to that of the Earth. I guess, since one face ...
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2answers
128 views

Is a 40 V/m electric field, coming from a wall socket and measured in air, a safety hazard? [closed]

I used a gaussmeter close to my child’s crib. Her head faces about 1 foot away from an electric socket. I was surprised it measured about 40 V/m at the socket and then gradually went down but was ...
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68 views

Can we rule out life swimming in the oceans of Europa and Enceladus on the basis of a lack of available energy?

Jupiter's moon Europa and Saturn's moon Enceladus (and several other moons too) have large subsurface oceans of liquid water, an ingredient considered essential for life. These two moons occasionally ...
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3answers
106 views

How unique is the length scale picked out by intelligent life? [closed]

Our human bodies pick out a length scale (let’s say 1m). How unique is this scale and why did it arise? In other words, how much smaller could humans, or multicellular lifeforms in general, be while ...
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44 views

Why don't we see/feel charged particles, penetrating our brains/retina?

If we see tracks in bubble or Wilson chamber, it means that particles are everywhere and can leave tracks in gases and liquids. They can also penetrate concrete of the building levels in the lab. So ...
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3answers
168 views

Do proteins interact through classical or quantum mechanics?

For the protein interactions that occur in our cells, do they "follow" classical mechanics or quantum mechanics when interacting? I have zero knowledge about quantum mechanics, but I was wondering ...
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1answer
40 views

On seeing and especially in the dark

Our retina detects the change in the electromagnetic field due to the jiggling of the atoms surrounding us as I understand the seeing process. In the total absence of a light "source", however, why ...
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4answers
3k views

What determines the top speed in ice skating?

I was watching a hockey skating competition. The best skaters are able to accelerate quickly and turn without losing much speed; however, most people have similar top speed around 20-25 mph. What is ...
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24 views

What are good books to study life sciences related physics at an introductory level?

I study medicine, but also love physics and I want to have this physical and mathematical perspective of what I learn. What are some good textbooks for studying physics for the life sciences (i.e ...
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2answers
124 views

How does tanning oil increase UV skin damage?

I see many websites claiming oils amplify UV waves. This would only seem possible if thicknesses caused no reflection as in a quarter-wave coating, but that seems hard to believe. So, is it a myth ...

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