Can You See Light in a Vacuum with a Flashlight?

[timetraveldude]

If you were in a vacuum and shined a flashlight would you see the light?

 

[The_Thinker]

Not unless there are dust particles present or you are shining it at something specific.

 

[Adrian Baker]

You can only ever see light when you look directly at the source or when it is reflected off something...

You can see the sun and stars, and we on Earth are in a vacuum!

 

[Lokolo]

its like the moon, we see the moon only because light from the sun is reflecting off of it onto our earth.

If you shined a torch into space, you wouldn't see the light unless it hits something on its way, and this is delayed (depending on how far away it is!). An example, turn your torch on, a light comes a year later off an object (planet maybe!), switch it off and the light will stop shining a year later.

Ps. you would need a very poweful torch

 

[12345]

It takes light from the sun 8min. to reach Earth, which means the sunlight you see now set off on it's journey from the sun 8min. ago.

 

[timetraveldude]

Not unless there are dust particles present or you are shining it at something specific.

Thank you. Your answer was the only good one. A simple question, a simple answer.

This raises some interesting points. If light can only be observed when it is interacting with matter what can be said about its existence when it is not observable?

 

[Adrian Baker]

Absolutely nothing.

 

[russ_watters]

Thank you. Your answer was the only good one. A simple question, a simple answer.

This raises some interesting points. If light can only be observed when it is interacting with matter what can be said about its existence when it is not observable?

Leading question based on a partial answer. Adrian is correct: You're going in the wrong direction.

 

[pallidin]

This raises some interesting points. If light can only be observed when it is interacting with matter what can be said about its existence when it is not observable?

It's existence is not affected. Light, or any other force, does not depend on observation for existence.

 

[timetraveldude]

Absolutely nothing.

Just because you can not observe something with your eyes doen't mean you can't say something about it.

 

[timetraveldude]

Leading question based on a partial answer. Adrian is correct: You're going in the wrong direction.

This is your view. You think that if you can not measure it with a machine or detect it with you senses it doen't exist. You are wrong.

 

[JasonZ]

This is your view. You think that if you can not measure it with a machine or detect it with you senses it doen't exist. You are wrong.

Noone questioned its existence (except perhaps yourself). Tell us what you believe can be said, since you seem to be looking for a specific (supportive?) answer.

-Jason

 

[timetraveldude]

Noone questioned its existence (except perhaps yourself). Tell us what you believe can be said, since you seem to be looking for a specific (supportive?) answer.

-Jason

You people need to learn how to have a debate.

 

[timetraveldude]

It's existence is not affected. Light, or any other force, does not depend on observation for existence.

Then how do you know it exists?

 

[Adrian Baker]

You people need to learn how to have a debate.

We are therefore so fortunate to have you here as a fine example...

This is your view. You think that if you can not measure it with a machine or detect it with you senses it doen't exist. You are wrong..

I'll obviously have to work on my technique...

 

[abertram28]

Then how do you know it exists?

how do you know it exists even when you 'see' it? how do you know a blinking light is a blinking light rather than your pulse in a tumor on your optic nerve?

i think you need to re-evaluate your thoughts on knowing and believing. I am betting you can't differentiate between the two. most people cant. when they 'see' something they feel that they know it, but really they are believing it. to know it, you must believe in it, true, but you must also know the conditions the predict it and the conditions that it creates. then you can evaluate whether something exists. i believe all science is hypothetical.

 

[timetraveldude]

how do you know it exists even when you 'see' it? how do you know a blinking light is a blinking light rather than your pulse in a tumor on your optic nerve?

Because other people see the same thing.

i think you need to re-evaluate your thoughts on knowing and believing. I am betting you can't differentiate between the two. most people cant. when they 'see' something they feel that they know it, but really they are believing it. to know it, you must believe in it, true, but you must also know the conditions the predict it and the conditions that it creates. then you can evaluate whether something exists. i believe all science is hypothetical.

Knowing is certain, believing is not. You know a vase because the mind that perceives the object perceives the object in accordance with the definition of a vase.

 

[abertram28]

Because other people see the same thing.

the major problem i see with that is that you cannot rule out coinicidence. similarly you can't say that if you don't see it but i do see that it doesn't exist. if its not two way, id say its not proof.

Knowing is certain, believing is not. You know a vase because the mind that perceives the object perceives the object in accordance with the definition of a vase.

i don't get it. you know why? cause i don't have a definition for vase in my mind. therefore, they simply cannot exist! you said it yourself, if others don't see it, its not really there.

</sarcasm>

 

[timetraveldude]

the major problem i see with that is that you cannot rule out coinicidence. similarly you can't say that if you don't see it but i do see that it doesn't exist. if its not two way, id say its not proof.

It is impossible that the number of people who understand red indicates stop is a conincidence.

i don't get it. you know why? cause i don't have a definition for vase in my mind. therefore, they simply cannot exist! you said it yourself, if others don't see it, its not really there.

</sarcasm>

If you don't understand the definition you don't perceive the vase.