Why can we see space, but not time?

[Jupiter60]

If space and time are really related, why is it that we can see space, but we can't see time?

 

[ZapperZ]

How are you able to see space?

Zz.

 

[Jupiter60]

I can see space right now. The space between me and my computer. I can see myself move through space, though not through time. I have to look at a clock to see my movement through time. Are space and time really related?

 

[Dale]

We don't see either space or time, we see light.

 

[ZapperZ]

I can see space right now. The space between me and my computer. I can see myself move through space, though not through time. I have to look at a clock to see my movement through time. Are space and time really related?

Actually, you don't see space. You see the object! And you do you know why you think you are seeing a 'distance'? Because (i) you have depth perception because of your two eyes and (ii) the light from the object reaches your eyes AT DIFFERENT TIMES! In other words, your sense of distance actually depends on some time differences! So if we apply your "logic" of seeing space, I could also argue that you're seeing time as well!

Zz.

 

[Chestermiller]

If space and time are really related, why is it that we can see space, but we can't see time?

By not being able to see time, I assume what you mean is that you can't see into the 4th dimension, even though you can see in the 3 spatial dimensions. This is because you are inherently a 3 dimensional being, and suffer from the physical limitation that you cannot see into your own fourth dimension. You can however see partially into the 4th dimension of other reference frames and objects that are moving relative to yourself.

 

[dipole]

You have to be precise asking these kinds of questions, and define what you mean when you say you can "see" space. Your eyes are able to gauge distance because of parallax - the image each eye sees is slightly different, depending on how far away something is. You measure distance, or percieve it, by measuring the parallax.

With time, you don't have a sensory organ specifically devoted to sensing time, at least not one you're so consious of as with your vision. However, you can feel the passage of time, you know that what you did this morning happened several hours ago, and that you went to sleep before you woke up.

You can "see" time by watching a clock, or water dripping, or anything which occurs in some regular way, but your eyes aren't directly meant to measure it.

 

[Emilyjoint]

We don't see either space or time, we see light.

mmmmmm...I don't think we do see light ! we see what light shines on.
I look at a candle and I see the flame because of light. I look from the side but I cannot see 'the light' from the candle pass me. If we could see light the space in front of me would be covered with criss cross lines of light ! Like a spider web or a mesh of some kind.

 

[ModusPwnd]

mmmmmm...I don't think we do see light ! we see what light shines on.
I look at a candle and I see the flame because of light. I look from the side but I cannot see 'the light' from the candle pass me. If we could see light the space in front of me would be covered with criss cross lines of light ! Like a spider web or a mesh of some kind.

I don't think so. Light is the only thing we can see. Light is what enters the eye. Of course you cannot see the light crossing in front of you... It has not entered your eye.

 

[A.T.]

The eyes see light.
The brain sees space.

 

[Dale]

mmmmmm...I don't think we do see light !

The function of the human eye is well studied. We see light.

 

[Dale]

The eyes see light.
The brain sees space.

That is a reasonable point. The brain "sees" time every bit as much as it "sees" space.

 

[A.T.]

The brain "sees" time every bit as much as it "sees" space.

And the brain doesn't need eyes to see space. People born blind grasp 3D space just fine.

 

[Emilyjoint]

The function of the human eye is well studied. We see light.

You have not given my quote as it was stated !

 

[Dale]

You have not given my quote as it was stated !

I quoted you exactly. Your quote, as it was stated, was wrong.

Our eyes see light, not objects, not space, not time.

 

[Jupiter60]

I don't think so. Light is the only thing we can see.

Not really. Well, not for most of us. There are some people though who have no more vision than to tell the difference between light and dark. Those people only see light. They have only light perception.

http://en.wikipedia.org/wiki/Blindness

Those described as having only light perception have no more sight than the ability to tell light from dark and the general direction of a light source.

 

[Drakkith]

Not really. Well, not for most of us. There are some people though who have no more vision than to tell the difference between light and dark. Those people only see light. They have only light perception.

http://en.wikipedia.org/wiki/Blindness

I don't know what you're getting at. The eye detects one thing and one thing only. Light. The brain then interprets the signals sent by the eye to form an image that you "see".

 

[Dale]

And the brain doesn't need eyes to see space. People born blind grasp 3D space just fine.

Another excellent point (you are on a roll A.T.!)

 

[Jupiter60]

I don't know what you're getting at. The eye detects one thing and one thing only. Light. The brain then interprets the signals sent by the eye to form an image that you "see".

What about shapes? The eye detects shapes. Shapes aren't light though. Though people with very severe visual impairment can't see shapes, only light.

 

[Drakkith]

What about shapes? The eye detects shapes. Shapes aren't light though. Though people with very severe visual impairment can't see shapes, only light.

The eye does not detect shapes. It detects the presence of light. Based on the pattern of signals your brain puts together the image, including the shape of things.

 

[Algr]

The eye can only sense photons that happen to enter the iris. It can detect the number of photons, (Brightness) some info about their frequency (Color) and also direction relative to the eye itself. (Shapes)

From there, the brain invents ideas such as "Space" and "Time" to develop a model of what it thinks is going on around you. Other senses like sound and touch can contribute to and extend this model. But you don't really "see" space; it might be better to say that you infer it.

 

[pbuk]

If space and time are really related, why is it that we can see space, but we can't see time?

Because although they are related, they are not the same thing. You may as well ask "if thunder and lightning are really related, why is it that we can see lightning, but we can't see thunder?"

 

[phinds]

Because although they are related, they are not the same thing. You may as well ask "if thunder and lightning are really related, why is it that we can see lightning, but we can't see thunder?"

Nice analogy !

 

[A.T.]

But you don't really "see" space; it might be better to say that you infer it.

The question remains why the concept of time seems different than the concept of space. Is it because they are objectively physically different, or because the way the brain works? Maybe it is because the thought process itself inherently requires the passage of time, and state changes over time.

 

[ZapperZ]

The question remains why the concept of time seems different than the concept of space.

But a priori, why should they be the same?

I wonder if an alternate universe, if these two concepts appear the same, someone's going to ask why they are not different?

Zz.

 

[Dale]

Is it because they are objectively physically different, or because the way the brain works?

They are objectively physically different. Space is measured with rods and time is measured with clocks. Since the same physical device cannot measure both it is clear that they are physically different.

The brain "sees" both space and time as you have eloquently pointed out, but that doesn't mean that they are both the same.

 

[Jupiter60]

I guess we don't actually see space. We have depth perception, but we're not seeing space.

 

[B4ssHunter]

i think that time is not something we can see , but rather something that just exists , its a 4ourth dimension but that doesn't mean we should be able to see it , you don't see space , you see object , and as objects come closer or go further or even stay in their position , time passes on and you know that , you can't go and watch a movie for instance then claim you didn't sense time or you didn't know time passed , its a perception that we might have created , the perception of time , whether it exists or not .

 

[mfb]

Actually, you don't see space. You see the object! And you do you know why you think you are seeing a 'distance'? Because (i) you have depth perception because of your two eyes and (ii) the light from the object reaches your eyes AT DIFFERENT TIMES! In other words, your sense of distance actually depends on some time differences! So if we apply your "logic" of seeing space, I could also argue that you're seeing time as well!

Zz.

For humans (and all other living creatures), it is impossible to use the tiny time differences to estimate any distances on earth. Light is just too fast. It is possible for sound, as that is slower.
With the moon or other objects, it would be possible - if we would have flashlights bright enough to see their spot on the moon (we do not).

Electronic sensors are better, they can measure distances with a precision of millimeters based on the propagation time of light.

 

[Borg]

Visually understanding objects is learned by the brain. The July edition of Scientific American had a good article about previously blind children in India who were given sight for the first time. They have a lot of difficulty assembling parts of a scene into a coherent whole which causes difficulty in even discerning two dimensions.

Here is a TED discussion by the author:
Pawan Sinha: How brains learn to see