The use of methods from the physical sciences to aid in the study of biological systems. Note that biophysics questions are only allowed if they are mainly about physics.

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205 views

Is the hard problem of consciousness an obstacle to finding a physical theory of everything? Why or why not?

I do not understand how, without understanding the mind and how (physical) neural interactions within the brain give rise to consciousness, one can have a definitive theory of everything. There will ...
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2answers
47 views

Can you hear vibrations through your bones?

If we have a source, like a speaker, but with no sound and only the vibrations, and this vibrations were transported to a surface which you can put your elbows on it and then put your hands to your ...
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1answer
71 views

What happens to photons, electrons, etc [duplicate]

What happens to photons when they hit our eye? where do they end up? if they generate heat, why our eye don't get overheated? Similarly what happens to electrons when the light hits certain metals, ...
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1answer
58 views

Literature on scientific achievements in physiological acoustics after Helmholtz [closed]

I'm greatly interested in theoretical/mathematical/physiological aspects of music and the corresponding acoustics. As everyone knows, the Greek already discovered that consonant sounds seem to ...
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1answer
84 views

What is one human power? [closed]

some time ago I was asked what the HP equivalent of a human was, looking into this apart from in the creation of steam engines the power definition 1 Horse power was set at the work of two of the best ...
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1answer
55 views

A sound that always seems to come from behind you

Many years ago I heard a radio broadcast featuring a beeping sound that always seemed to come from behind me. The announcer said that the sound would have this quality and it did, even when I turned ...
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3answers
90 views

The second law of thermodynamics and life on Earth [closed]

The second law of thermodynamics says that order always decreases in a system. The appeareance of life seems to contradict that law, but if we invoke the Sun, everything faals into place again. But ...
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1answer
26 views

Correcting Myopia with a Diverging Lens

My textbook says that a diverging lens works by rendering the object a virtual image at the myopic eye’s far point. However, wouldn’t the eye then perceive an object farther than its far point at the ...
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1answer
59 views

Change of internal energy to kinetic energy

Why do we feel tired while running as during running we are increasing our kinetic energy. I understand that the energy inside us(from food or something else) is being converted to KE while running ...
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1answer
32 views

Infrared light and heat

I know that mid wave IR, long wave IR, and far IR are all infrared light that we feel as heat. Often, even when it is cold and windy, if I face the sun in a sunny spot it feels like it is 80 degrees F ...
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1answer
41 views

Missing causal correlation between distant parts in the brain [closed]

The Wikipage on the Primary Motor Cortex says: Evarts suggested that each neuron in the motor cortex contributes to the force in a muscle. As the neuron becomes active, it sends a signal to ..., ...
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2answers
73 views

What law of physics did these people think they disproved?

I was trying to understand the Physics of how water gets to the leaves of a tree and found this article which claims some experiment disproved a 300 year old law of Physics. Sounds pretty unlikely... ...
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3answers
104 views

Can higher level animals have lower entropy than the food they consume?

If there is plant source of energy 100Cal and an animal source of energy 100Cal for a human being, where the animal derived that energy from a similar plant source, can we say for sure that the animal ...
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1answer
354 views

What would happen to the human body if we went almost at the speed of light? [duplicate]

If we were to travel almost at $299\,792\,458~m/s$, or the speed of light, what would happen to the human body? Would the human body stay the same or would there be consequences that would harm the ...
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2answers
93 views

Laser tattoo removal

I would like to know if someone could please briefly explain how laser technology of tattoo removal works? And second, could there possibly be any dangers to cells, specially on bones?
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1answer
71 views

A parameter to quantify instability in flight

Suppose I have plotted the body angles of a flying aeroplane.I have two such plots. One of a normal plane, and the other plot in which a primary sensor of the aeroplane is removed. So with the absence ...
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1answer
203 views

Does the space between molecules have no pressure?

In any living organism there exists are space between cells filled with interstitial fluid. Loss of this fluid into abnormal areas (3rd spacing) can cause relative to severe hypo-volemia. The fluid ...
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1answer
745 views

Calories burned doing 1 squat [closed]

To calculate the calories burned doing 1 squat, wouldn't it simply involve the distance that your center of mass is moving and your weight? I read some other article that said your legs act as levers, ...
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1answer
43 views

Measuring life through radiation

Dramatic title, I know. But it's shorter than Measuring a person's effective mass through radiation and comparing it to their weighed mass and I figured this would get people's attention. I just ...
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1answer
733 views

How is tritium illumination possible without negative health effects?

Turns out there's tritium illumination - a tiny very strong plastic tube will be covered in phosphor and filled with tritium. Tritium will undergo beta decay and a flow of electrons will cause the ...
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2answers
3k views

Why the pressure of atmosphere doesn't crush you when you e.g. walk outside?

Why the pressure of atmosphere doesn't crush you when you e.g. walk outside? I mean the density of air is $1.26 kg/m^3$, so with $100 km$ above us, it exerts much pressure on you when you walk ...
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1answer
122 views

People eating and gaining energy

Let's say we have 100 grams of chocolate which has 571 kilocalories (so it's about 2.4 megajoules) and we have barbell which weights 100 kilograms and need to lift it to 0.5 meters height. So how ...
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1answer
44 views

Energy/entropy in transport of molecules across cell membranes

I'm asking a "Maxwell's Demon" question. I've read statements that sorting molecules and sending them to one side or the other of a barrier requires work, but none of these statements have explained ...
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1answer
32 views

Plausibility of the distance estimation in a cycle ergometer gym exercise

A friend of mine pedaled for an hour on a cycle ergometer, a stationary bicycle in a gym. At the end of the ride the cycle computer reported a distance of $40\:\mathrm{km}$ and an average power of ...
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1answer
69 views

What is the real definition of entropy? [duplicate]

In our bio class our teacher told us that entropy was the amount of heat lost by a system. But I had learned before that entropy was like chaos / disorder in a closed system. Which definition Is ...
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1answer
71 views

Measuring friction coefficient with a inclined plane. Beetle problem

I want to measure friction coefficient between a beetle and an inclined plane (angle of inclination $\theta$). As we all know, friction coefficient $\mu$ is given with: $\mu=tg \rho$, where $\rho$ is ...
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1answer
40 views

Solving for the firing rate of a model neuron

I'm trying to decipher Figure 15.2A on page 442 of this book chapter. It plots the firing rate $\nu$ of a model neuron against its mean current $\mu_c$. The equation used to calculate the firing ...
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2answers
69 views

Loss of temperature of a sphere [closed]

I am trying to get an intuition of whether it theoretically seems possible for a living cell (a yeast for example) to regulate its own temperature. Let's consider a spherical living cell which radius ...
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1answer
252 views

Are muscle cells electric dipoles?

I'm wondering how we can detect the electrical activity of a muscle cell. My initial thought on this question was that the membrane potential, around $\Delta V_{\text{membrane}} = -80mV$ across the ...
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1answer
58 views

Will I sunburn faster when driving compared to being parked?

I'm not sure if the same logic applies to light and rain when comparing running/driving with a stagnant situation. See, e.g. Why does driving faster make my windshield catch more rain? Suppose I have ...
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1answer
119 views

What happens when a bird lands on a power line?

I know that when a bird is sitting on a high-voltage power line, virtually no current flows through the bird because there is (almost) no voltage drop between its legs, the two points are ...
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1answer
64 views

Factors affecting pain of static electricity shock

Referring to How to avoid getting shocked by static electricity?, someone I knew suffered much pain from static electric shocks when touching door knobs or car doors where I didn't feel anything doing ...
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1answer
31 views

a question regarding Fourier transform in electron microscopy

I have recorded a micrograph of a 2-D array at a magnification of 43,000x on my DE-20 digital camera, which has a 6.4 μm pixel size and a frame size of 5120 × 3840 pixels. This magnification is ...
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3answers
82 views

Work power and energy

When you push your bicycle up on an inclined the potential energy of the bicycle and yourself increases. Where does this energy come from?
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3answers
302 views

How to generate Red light from a Blue-Dominated Spectrum [closed]

I have a white LED light source, the spectrum of which looks as follows --- I want to filter out red light from this white LED source. But as you can see the spectrum dwindles in the red zone. And ...
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1answer
177 views

How do you calculate the power needed to keep something stationary? [duplicate]

1) If I place an object on a table, it will sit there forever. There's no change in potential or kinetic energy. If I hold the object at the end of my outstretched arm, eventually I can't do it ...
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1answer
75 views

What are some publications which continue Schrödinger's “What is life?” discussion?

I'm looking for modern publications on the physical nature of life in which the primary reference is to the discussion started by Schrödinger in 1944 in his book "What is life". For example, ...
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2answers
438 views

Is two cars colliding at 25 mph the same as one car colliding into a wall at 50 mph in reference to injuries?

This question has been asked using 50 & 100 mph reference, see this Phys.SE post and links therein. However, I am interested in the potential injuries to occupants of the autos. As the one going ...
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1answer
385 views

Temperature gradient in body [closed]

Is there a Temperature gradient in the human body? especially I have heard that the eye is colder than other places? Is that right?
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1answer
726 views

What is the difference between “in-plane shear modulus” and “shear modulus”

In the wiki it is article only about shear modulus and it is written that it's unit is Pascal. At the same time in all researches about Red Blood Cells shear stresses, authors write "in-plane shear ...
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1answer
172 views

Dynamic Light Scattering

In the Dynamic Light Scattering experiment, how is the intensity distribution plotted against time, keeping in view the multiple scattering of photon particles in laser ?
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1answer
38 views

Could we recognise if time was running at a different rate for one species than another? I.e a human and an ant

My question is quite simple if time ran at a different speed for smaller creatures, how would we be able to observe this or confirm by experiment?
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0answers
12 views

Height estimate by step profile?

With so many current apps in mobiles tracking number of steps based on analyzing the accelerometer's measurements in time during a walk, I was wondering the following: Would it be possible to ...
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1answer
37 views

Is there a pressure differential between the skin and any parts inside the human body? [closed]

Since most of the human body is never directly exposed to the atmosphere, is there a meaningful difference in pressure between any internal organs and the skin? If so, how do open wounds which ...
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4answers
128 views

What is the theoretical fastest way a human could be accelerated without dying? [closed]

Humans can survive maybe 3-10 $g$'s sustained acceleration when applied to their backs, like in a rocket launch. This question is not about that. I'm wondering about alternative theoretical future ...
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1answer
28 views

What is the different between Poisson Nernst–Planck and Poisson Navier–Stokes in the Electrolyte?

I am now studying about electroosmosis flow phenomena which is governing by the Navier-Stokes equation and Poisson equation. By combine these two equation we can describe the electrolyte flow velocity ...
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1answer
32 views

Why divide surface area to volume for strength in living beings? [duplicate]

As the title says, why divide surface area to volume for strength in living beings ? I mean why all surface area ? Shouldn't it be area touching the ground ? Thanks in advance! :)
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0answers
18 views

Hiccup in frequency domain

Main question: What would the Fourier transform of hiccup look like? This question is too general so let me elaborate a few possible approaches. Hiccup just as a series of pulses (of no matter what ...
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0answers
19 views

Electric dipole moment of a coaxial cable?

Question Does a cylindrical coaxial cable have a net electric dipole moment, and if so why? Context I am trying to understand why the heart has a net electric dipole moment. In the heart we have ...
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1answer
37 views

Generallized Canonical Ensemble - Isobaric Ensemble

I am trying to understand the way generalized canonical ensembles like the pressure ensemble are derived from the standard canonical ensemble. In the derivation for the standard form, one defines a ...