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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.

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Why the Sun has a higher temperature than humans?

Why the Sun has a higher temperature than humans if the energy/gramme of matter ratio of humans is greater than that of the Sun?
Aarnihauta's user avatar
0 votes
0 answers
74 views

Does the Host Rock of This Mexican Hyalite Show Signs of Uranium Minerals? I Previously Cut It and Am Now Concerned

I previously cut a Hyalite specimen from Zacatecas, Mexico. Using a Geiger counter, I measured a slightly higher level of radioactivity on the cut surface compared to the environment. Although I know ...
Flame Gems's user avatar
1 vote
1 answer
56 views

What am I seeing while closing my eyes? [closed]

We all must have noticed that when we close our eyes or rub them with our hands we generally see some patterns,shapes or colors. I am still unable to understand what are these things called and whe do ...
Ishaan's user avatar
  • 517
0 votes
2 answers
110 views

Are calories an appropriate measurement of energy for biological systems? [closed]

According to this source, a calorie is an inappropriate unit to quantify the energy contained in food because a "calorie is heat energy" and "humans don't absorb photons" but ...
Jon Behnken's user avatar
1 vote
2 answers
124 views

Why clothes keep us warm?

I want to understand why clothes keep us warm. I understand that they reflect back thermal radiation and also trap air thus significantly reducing cooling due to thermal convection. My question is, do ...
Plemath's user avatar
  • 208
4 votes
2 answers
106 views

What does life (photosynthesis) change for entropy? A thought experiment

The relationship between entropy and life is complex and has even "philosophical" ramifications. The following thought experiment seems simple enough to bring a clear answer, but I'm unsure ...
YAG's user avatar
  • 143
3 votes
1 answer
98 views

Does the Kardashev Scale have any practical application?

As the question states: are there any practical applications of the Kardashev Scale?
Dancrumb's user avatar
  • 1,058
0 votes
2 answers
65 views

Are these levels of RF radiation harmful?

I live on the top floor of a building that has four 5G antennas on the roof. The house is curved, and from my viewpoint, I can partially see one of the antennas pointing towards me. Curious about the ...
Armands L.'s user avatar
15 votes
4 answers
8k views

If microwave ovens run at 2.4 GHz, what is the long-term effect on living tissue of exposure to this frequency, but with a thousand times less energy?

Very low power electromagnetic waves with a frequency of 2.4 GHz can't cook anything. That's obvious, despite the heating effect such radiation has on water. However, what if such an object containing ...
Mesijé vopřenej Vo zeď's user avatar
0 votes
1 answer
73 views

Can a liquid become supersaturated by a dissolved gas when going from a lower to a higher pressure?

This question has spawned from a discussion between myself (a novice diver but an engineer), and a diving instructor. The training materials indicate that if you are driving and go from sea level, to ...
ScottishTapWater's user avatar
0 votes
2 answers
90 views

Light from an eclipse [closed]

Why do people fry their eyes staring at the sun during a solar eclipse? Is it that they stare at the sun for a long time---longer than if they stared without an eclipse? Or is it that during the ...
Thad_The_Man's user avatar
0 votes
1 answer
76 views

Calculating jumping distance?

I'm trying to figure out how to calculate the jumping distance of a person or animal based on body weight and initial speed, but I can't seem to find any relevant information online about this. Is ...
Papa Solen'ya's user avatar
0 votes
0 answers
671 views

Why does a CT scan with contrast make you feel warm?

I recently had a CT scan with IV contrast liquid. I was warned it might make me feel warm and that this is normal. I had an amazing sensation of heat moving down my body. All my searches tell me that ...
Skrrp's user avatar
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0 votes
0 answers
78 views

How strong of an MRI machine would be able to kill a person?

Previous title: How strong of a magnetic field could dissociate water molecules? (Changed as this is probably not possible) This is part of an attempt to answer the question 'How much MRI is enough to ...
upbeatmeeting's user avatar
1 vote
0 answers
35 views

Cosmic web distribution and neuron system similarities

Does the cosmic web follow Gaussian distribution? If so, is that the reason it resembles the human neuron system? Does the human neuron system follow Gaussian distribution too? (sorry if this deviates ...
Kellan Heerdegen's user avatar
1 vote
1 answer
55 views

Why and how white noise cancels other background noises?

This idea of white noise cancelling other background noises is quite popular these days and I always wonder how it works? https://www.youtube.com/watch?v=nMfPqeZjc2c This is a sample of white noise. ...
Devansh Mittal's user avatar
0 votes
2 answers
84 views

Is holding a falling object the same effort as lifting it?

It seems like lifting objects requires more effort compared to dropping them, although the law of conservation of energy still applies. As discussed Physics Stack Exchange answer, energy transfers ...
Manticore's user avatar
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1 vote
2 answers
117 views

Is it plausible that Earth's magnetism can induce heart attacks by affecting red blood cells? [closed]

https://ui.adsabs.harvard.edu/abs/2014cosp...40E1114G/abstract#%3A~%3Atext%3DIt%20was%20shown%20statistically%20that%2Ccomparison%20with%20quiet%20geomagnetic%20conditions This study says that on ...
Malcom's user avatar
  • 39
0 votes
2 answers
58 views

Why do the proteins in our eye have a continuous (bell shaped) absorption spectrum?

From quantum physics, I would expect that seeing e.g. red would excite the 564nm energy level of the Photopsin protein. I would also expect to only see (apart from some small smeering out) that we are ...
mtooling's user avatar
0 votes
1 answer
40 views

How wave speed affects perception?

If there were 2 sound waves with the same wavelength and amplitude, but different speeds, how would my perception of the waves vary? How would my perception vary if they were light waves instead of ...
VV_721's user avatar
  • 133
1 vote
2 answers
55 views

Would quantum superposition stop if we observe the particle in the case of photosynthesis?

I started looking up more into quantum biology from photosynthesis to genetics mutation and how they are explained by quantum properties. my question is about the case of photosynthesis: quantum ...
Rihab's user avatar
  • 11
0 votes
1 answer
68 views

Why does cigarette smoke stay so stubbornly on our bodies? [closed]

How does anything stick to anything, for that matter? Another example: why does perfume also stay so stubbornly on our bodies? And why do some perfumes stay longer than others on a fundamental level?
damacc's user avatar
  • 9
-1 votes
2 answers
58 views

How do dark color varies from people when seeing the back of their eyelids?

Depending on the light source, the back of people's eyelids either be black or dark gray depending on what lit environment they're in? the how does eyes function when people have the back of their ...
Amber Alvia's user avatar
19 votes
6 answers
3k views

Can human ear hear 4 Hz frequency, if I tap my hand 4 times per second on table?

Frequency means the number of repetitions per second. Humans can hear between 20 Hz and 20 kHz, but I have a very basic question: if I tap my hand four times on a table per second, it means I am ...
Avinash Agrawal's user avatar
8 votes
4 answers
3k views

Do colours which are not visible to human eyes exist?

Are there any colours that our human eye cannot comprehend but other animals can see? The ability to see colours is the property of our eyes. For example an average dog would see less colours than us. ...
Aleph's user avatar
  • 412
2 votes
5 answers
229 views

Power Generation in a Bicycle

Consider a person pedaling a bicycle, if we consider the system consisting of the rider and cycle as a total and apply work energy conservation we can see that whatever force the rider applies on the ...
L lawliet's user avatar
  • 143
-4 votes
1 answer
84 views

Are there laws of creation for biological life? [closed]

I am no scientist, but I do love science as well as the unknown. Are there laws of creation for biological life? Would it be safe to assume that our bodies are made up from things that came directly ...
The Grout Savior's user avatar
1 vote
2 answers
50 views

Optimizing accuracy of different basketball shots [closed]

I have a high school math project and chose to work on basketball trajectory because I thought I would enjoy it the most. But honestly, I have a hard time calculating a 3D trajectory. So I thought ...
Nicolas's user avatar
  • 11
0 votes
1 answer
300 views

Could a human-sized flea really jump over the Eiffel Tower?

I am puzzled why so many people think such a large flea could jump as high as the Eiffel Tower. We know that a 3mm long flea can jump 150mm, which is 50 times its own length. So I suppose it's ...
Brian F's user avatar
  • 151
18 votes
3 answers
22k views

Why did these algae grow like this in the pool? Are these curves the gravitational equivalents of the bell curve?

My friend sent me these pictures of a pool that has been abandoned for a long time, and we are curious about the reason behind the peculiar growth of algae in this pattern. The needle-like towers of ...
Tripasect's user avatar
  • 318
12 votes
5 answers
2k views

Why is cycling easier while standing on the pedals?

On high slopes and rugged terrains, riding a bicycle while standing on the pedals is easier. Even though I cannot physically define what is "easy"; since it is a feeling that my body ...
AlphaLife's user avatar
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0 votes
0 answers
421 views

How fast can the human hand move?

I was playing with my six year old daughter the other day with her toy airplanes (I’m a pilot and she’s very interested in aviation now). I took the little F16 toy and flew it passed her as quickly as ...
Cjh199712's user avatar
1 vote
0 answers
108 views

Is there a depth under which the buoyant force is no longer sufficient to bring a diver back to the surface? [duplicate]

I came across the story of diver Yuri Lipski who died while diving in the Blue Hole. This made me wonder something and it may be a stupid question but I thought I'd ask: For a human diver with normal ...
Fermin C's user avatar
10 votes
2 answers
5k views

Reverse blood flow in an IV

When the IV drip for a patient is completed, the patient's blood will flow back. This is apparently due to the pressure difference. However, IV needles are inserted into veins in the direction of ...
Starlight's user avatar
  • 347
-1 votes
2 answers
76 views

Is this statement accurate: We are 4D beings (l,w,d,t) with the ability to visualize in 3D (using our brain) and see in 2D (using our retinas)? [closed]

I've read conflicting information on us being 4D beings (length, width, depth, time) and in what dimension we are able to see. Interested to hear your thoughts, especially if you provide sources.
Benjamin Awerkamp's user avatar
11 votes
2 answers
4k views

Is it correct to say that "WE" feel only 5/140 of the actual weight of brain as buoyancy acts on brain due to cerebrospinal fluid?

Many sources of biological sciences (e.g.https://medium.com/@drvnx/what-is-that-thing-without-which-we-are-dead-f556fb1029ef ) say that the actual weight of brain is almost 1400gwt but as brain ...
Shinnaaan's user avatar
  • 1,357
0 votes
1 answer
172 views

Can the human eye see the images of 300 nm light on a screen through a diffraction grating?

In my textbook there is a question as follows: A diffraction grating with 200 lines per mm is placed between a monochromatic light source and a screen. The distance from the grating to the screen is 2....
Kantura's user avatar
  • 1,329
30 votes
7 answers
9k views

Why does blowing a whistle in someone's ear damage it more than blowing directly in their ear? Won't the whistle reduce overall energy?

If I blow really hard from a whistle near someone's ear, it'll hurt a lot. But if I blow directly at a person's ear, it won't hurt nearly as much. But shouldn't the whistle (or any other obstruction) ...
chausies's user avatar
  • 1,090
1 vote
0 answers
60 views

How long will oxygen last in a $3\times 3\times 3 $ meter room for one person? [closed]

Let's assume that the windows and doors are tightly closed. How can I calculate at what moment I will feel a lack of oxygen and my well-being will worsen? Can one person completely consume all the ...
Tamila Ambeon's user avatar
13 votes
7 answers
5k views

Are human eyes interferometers?

It seems like 2 eyes is enough “wetware” to do interferometry inside brain. Can you definitely see some reason why this could not be happening, or some way to test if it does happen?
Euphorbium's user avatar
0 votes
1 answer
158 views

Does the human brain use random number generators? [duplicate]

Neurons fire depending on the impulses they get from other neurons. This seems to be 'deterministic'. However, sometimes it might be useful to use random processes instead. Does the human brain have ...
Riemann's user avatar
  • 1,440
5 votes
1 answer
228 views

Generation of order on the Earth

I learnt in a course on Biological Physics that it is possible to generate order without violating the second law of thermodynamics. This can be done if "high quality" energy is delivered to ...
eeqesri's user avatar
  • 1,488
1 vote
2 answers
75 views

The sun's neutrinos and the brain [closed]

Is it possible for the sun's neutrinos to be detectable biologicaly . Or what is the simplest way for a experimenter to detect neutrinos externally?
Levimega's user avatar
1 vote
1 answer
108 views

Question about the 2nd law of thermo

In some ways the 2nd law of thermodynamics appears to be violated by the creation of large molecules like proteins. The reason this seems to be a violation is because individual atoms become much more ...
scl's user avatar
  • 95
-4 votes
5 answers
484 views

How is abiogenesis not a violation of the second law of thermodynamics?

Randomly traveling molecules plus random changes in temperature, pressure, acidity, electric charges equals a cell. That is a decrease in entropy. How does that not violate second law of ...
Bob's user avatar
  • 137
0 votes
1 answer
493 views

What happens, if amino acids are exposed to extreme heat?

What will happen to amino acids if they are exposed to extremely high temperature such as the temperature of the Sun? Do the amino acids become more simple structures?
SnoopyKid's user avatar
  • 364
12 votes
2 answers
2k views

Which electrons kill you during electrocution?

I understand that there are three velocities in play in a circuit (I haven't studied Physics past high school so give me some rope) v1: the velocity by which the electrical field propagates through ...
Marcus Junius Brutus's user avatar
0 votes
3 answers
614 views

Out running a bear

I was going to ask this in wilderness but I’m pretty sure we’ll need some math to find out the real answer. They say you can’t out run a grizzly bear because they run about 35 mph. While the average ...
Luke's user avatar
  • 125
5 votes
3 answers
593 views

What's the reason that it requires less effort to walk against an escalator (to stay stationary) than walking up stairs?

I had this discussion with my relatives about the reason why it feels like you spend less energy on a step machine in the gym (basically an escalator that goes down), than it is to move up some stairs....
user3635700's user avatar
2 votes
0 answers
92 views

In theory, how fast could I possibly serve in a game of ping-pong?

A tennis player can serve in a more or less straight line from their racket to the service box on the other side of the net: there's a direct line of sight. That means that there's no inherent limit ...
Daniele Procida's user avatar

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