74
votes
Why aren't we bumping into objects outside of the visible range?
We do.
Birds fly into windows.
The first time I saw glasses with an anti reflection coating, I tried to poke my fingers through. I was curious why the frames had no glass in them.
You don't exactly ...
- 45.6k
46
votes
Why aren't we bumping into objects outside of the visible range?
It's a good question. but the answer is basically evolution. Organisms that frequently bumped into things that they couldn't see/detect were easy prey and so quickly removed from the gene pool.
- 60.3k
34
votes
Why aren't we bumping into objects outside of the visible range?
Something that hasn't been mentioned yet (perhaps because it's too obvious): if an object isn't transparent, but rather doesn't reflect any light of the visible spectrum, the first instinct might be ...
- 3,461
20
votes
Why aren't we bumping into objects outside of the visible range?
I think your nephew is thinking something like this: Blue objects reflect blue light, and red objects reflect red light. But what about objects whose color is infrared? Why don't we bump into them?
...
- 3,680
18
votes
Why aren't we bumping into objects outside of the visible range?
As mmesser314 answered, in fact we do. When light finds the surface of a material, three different phenomena happens: transmission,absorption and reflection. Reflection is the simplest one, it is ...
- 3,262
13
votes
Why aren't we bumping into objects outside of the visible range?
Easy.
Glass doors are a simple example, but they are SOMEWHAT visible because of the refraction of the light. And the glass is not absolutely transparent either.
Just turn off the lights at night.
You ...
- 8,249
11
votes
Why aren't we bumping into objects outside of the visible range?
Visible light encompasses a wide range of frequencies. So for something to be totally invisible to our eyes, it would have to be transparent in all these frequencies. Natural objects like this are ...
- 1,199
5
votes
Why aren't we bumping into objects outside of the visible range?
I feel like some of the answers miss that this question actually works in reverse.
Why did our - and most animals' - eyes evolve to see EM radiation specifically in this range of frequencies? Because ...
- 481
4
votes
What is the general energy expresion for a massless particle?
The Planck relation
$$E=hf$$
is valid for all particles, massive $(m\ne 0)$ and massless $(m=0)$.
The energy-momentum relation
$$E^2=(cp)^2+(mc^2)^2$$
is valid for all particles.
The relation
$$E=cp$$ ...
- 41k
2
votes
If the current frequency is within the human hearing range, why can't we hear it?
If the current frequency (50 Hz or 60 Hz) falls within the human hearing range (20 Hz to 20 kHz), why can’t we hear it?
Human ears detect vibration of air molecules inside the ear. If some object is ...
- 15.2k
2
votes
Why aren't we bumping into objects outside of the visible range?
Your nephew has a really good intuition for why vision is so interesting! As several of the above answers have noted, sometimes we do bump into objects because their interactions with visible light ...
- 3,387
1
vote
What is the exact nature of molecular vibration in solids and how does it relate to an object's natural fundamental resonant frequency?
The core issue is the indirect link between microscopic atomic vibrations (phonons, $\omega = \omega(\mathbf{k})$) and macroscopic resonant frequencies in a solid, specifically an iron tube. It's not ...
- 186
1
vote
Theorized tone of two engines combined
The "tone" produced by an engine exhaust depends on the size and shape of the exhaust pipe, which will amplify some frequencies from the engine noise and will supress others. So if you ...
- 60.3k
1
vote
Why aren't we bumping into objects outside of the visible range?
The "visible range" refers to frequencies. Objects are not frequencies. So it doesn't make sense to refer to an object as being "outside the visible range". You may be using that ...
- 9,116
1
vote
Why aren't brightness and loudness represented as spectra?
They can be.
In many applications, people just want to know about or control the overall amplitude of a signal (think turning the lights or the radio up or down), and don't care to know or control ...
- 10.4k
1
vote
Accepted
Why aren't brightness and loudness represented as spectra?
The problem is terminological - Brightness is a subjective characteristic of human light perception, not a physical quantity.
Light intensity is more physical term, but it may mean many different ...
- 65k
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