The biology tag has no wiki summary.
21
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2answers
2k views
Why is the sky not purple?
I realise the question of why this sky is blue is considered reasonably often here, one way or another. You can take that knowledge as given. What I'm wondering is, given that the spectrum of ...
14
votes
6answers
2k views
Are human eyes the best possible camera?
I am not a physiologist, but whatever little I know about human eyes always makes me wonder by its details of optical subtleties. A question always comes to mind. Are human eyes the best possible ...
14
votes
2answers
1k views
Why don't electric fish shock themselves?
Fish like electric eels and torpedoes have specially designed nerve cells that allow them to discharge hundreds of volts of electricity.
Now, while pure water is usually nonconductive, the dissolved ...
9
votes
4answers
3k views
How can a human eye focus on a screen directly in front of it?
I am asking this question here because I think the answer has something to do with the way light is bent as it's captured through the eye.
I saw a show a while ago about tiny screens on contact ...
7
votes
2answers
664 views
Why are smaller animals stronger than larger ones, when considered relative to their body weight?
I am interested in why many small animals such as ants can lift many times their own weight, yet we don't see any large animals capable of such a feat.
It has been suggested to me that this is due to ...
6
votes
2answers
591 views
How to distinguish female and male voices via Fourier analysis?
What makes one, without looking, be able to identify the gender of the talker as male or female?
I mean if we Fourier analysed the voice of males and females, how the 2 spectrums are different which ...
5
votes
2answers
57 views
Sillicon based life
My question may not be suitable here, because it's more of astrobiology. Life as we know, is carbon based.
Is it possible life based on silicon?
What will be the conditions for habitability for ...
5
votes
1answer
269 views
Would travelling at relativistic speeds have any impact on human biology?
If a person was sitting on a craft that has accelerated to near light speed speed from Earth (e.g. 99.999% of light speed) would there be any impact on his or her human biology due to relativistic ...
5
votes
2answers
347 views
Sunflowers and radioactivity
I read yesterday that sunflowers were used and to cleanup radioactivity at Chernobyl and the Atomic Bomb sites in Japan and may be used as part of a campaign to clean up the Fukushima area.
But my ...
5
votes
2answers
172 views
Effects of a very large magnetic field on the human body
Ever since reading about the NHMFL I have always wondered about this and asked several people without getting a good satisfactory answer. My question is, considering the simplest case let's say a ...
5
votes
1answer
1k views
How much sky do we see at any one moment?
When we look at any particular point the sky, what percentage of the celestial sphere do we see?
This question arises from the notion that on average there passes one meteor per hour overhead. So ...
4
votes
2answers
1k views
How can an an ant lift 50 times its own weight and pull 30 times its weight?
According to many sites like this one, an ant can apparently lift 50 times its own weight and pull 30 times its weight. Is it true?
Can it be proved using physics? Though most sites agree that an ...
4
votes
1answer
46 views
What is the minimum pressure difference for your ears to pop?
I'm assuming the answer to this largely varies from person to person. Assuming you could instantly change the pressure around your head by amount $\Delta p$, what is the minimum $\Delta p$ for your ...
3
votes
2answers
333 views
Human perception of distance
When we see things around us, distant objects look smaller to our eyes than nearby objects do.
Is there any physics-related reason why our eyes or brain perceive things like this?
Or if this is ...
3
votes
1answer
137 views
Why (infra-)red light is not used in diagnostics?
I noticed that human body conducts red visible light quite well. A hand placed over a powerful red lamp seems to be semi-transparent while over any other color it does not.
Possibly the light ...
3
votes
1answer
62 views
Relation between Casimir and hydrophobic effects
Background
Some years ago I was studying "Fundamentos de biología" (Biology fundamentals) and learned how the lipids create a bilayer due to the water repulsion. Some time later I learned that this ...
2
votes
4answers
353 views
How does the introduction of living things into a closed system affect the rate of change of entropy?
Does the introduction of living things into a closed system increase or decrease the overall rate of change of entropy of a system?
2
votes
6answers
2k views
Limit of human eye flicker perception?
I am designing a LED dimmer using software-controlled Pulse Width Modulation, and want to know the minimum PWM frequency that I must reach to make that LED dimming method indistinguishable from ...
2
votes
2answers
333 views
Are cosmic muons causing mutations or even influence evolutionary rate?
As there are experiments studying influence of cosmic rays on organisms,
http://www.ncbi.nlm.nih.gov/pubmed/11541768
I ask my self, if there any influence to DNA from atmospheric muons on the Earth ...
2
votes
1answer
506 views
Effects of high frequency lighting on human vision?
I have a couple of different LED flashlights. One of them has three different "modes" of brightness, and the way it controls it is via pulse width modulation (PWM). Here is a picture that illustrates ...
2
votes
4answers
2k views
What could make the SWITL materials behave like this?
SWITL - what could this be? Ultra thin paper with some adhesive that binds to fat? (or as I originally thought, a hoax)?
A robotic hand to scoop gel-like substances...
...
1
vote
3answers
128 views
Can endergonic reactions occur outside of living organisms?
If the Gibbs free energy equation is defined as:
∆G = ∆H - T∆S
And the amount of energy/work released from a reaction is:
...
1
vote
1answer
102 views
Will a plant grow faster or slower when affected with less/more gravitational forces
Will a plant grow faster when you would apply more upward gravitational force?
and/or
Will a plant grow slower when you would apply more downward gravitational force?
0
votes
1answer
73 views
What is the $Q_y$ transition in a bacteriochlorophyll?
Bacteriochlorophyll (BChl) are pigments that occur in the photosynthetic mechanisms of bacteria. I am studying some papers on the excitonic properties of BChl's, and the term $Q_y$ transition comes up ...
0
votes
1answer
112 views
Is a low-current electrical arc harmful to humans?
I've heard that electrical flux non-destructive particle testing machines are considered safe because they use less than 2 amps. I have seen an arc created between two objects do considerable damage, ...
0
votes
1answer
170 views
Reeh–Schlieder theorem in QFT and entanglement in biological systems
Context: There have been a few papers out recently which mention how photosynthesis in plants might have connections to entanglement, or even perhaps that entanglement is causing photosynthetic ...
0
votes
1answer
161 views
Physical Explanation of Being Able to “Think” [closed]
This may look like a philosophical question, but I'm looking for physical explanations (if there's any), that's is why I'm asking it here.
What is the ability of thinking? We are all creatures ...
0
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0answers
412 views
How to calculate the resonance frequencies of human being cells? [closed]
I would like to calculate the human being's cells natural resonance frequencies.
can someone please help we with that? where should I start from?
0
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0answers
70 views
How and where is the information which constitutes memories stored in our brain? [closed]
I am wondering if the information was stored as in computers, with a sort of condensators system, but this would imply a certain discretization, and seems to be too restrictive.
Therefore, how the ...
-1
votes
1answer
24 views
Maximum depth for bacteria on rogue planets [closed]
If microscopic life evolves on a planet which is subsequently ejected from orbiting its star, then the planet would cool down. How deep into the interior of the planet could organisms reach, assuming ...
-1
votes
0answers
34 views
How does research in biology and physics differ? [closed]
I am an apple tree biologist and I remember a presentation from a physics professor who said physics is much more concrete and precise than in most present day biology. Could you share your thoughts? ...
