[Kryptid]

You are looking at water with a vagueness, try being underwater in a swimming pool.   You can see the entire length of water between you and the side of the pool.

So what?

You say the surface is reflecting light so you can see the water, what is the reflected  visible wave-length?

It's whatever wavelength happened to strike the surface of the water. That should be obvious.

[guest39538]

You are looking at water with a vagueness, try being underwater in a swimming pool.   You can see the entire length of water between you and the side of the pool.

So what?

You say the surface is reflecting light so you can see the water, what is the reflected  visible wave-length?

It's whatever wavelength happened to strike the surface of the water. That should be obvious.

It is not a wave-length between 400-700nm that is for sure, that should be obvious .

[Kryptid]

It is not a wave-length between 400-700nm that is for sure, that should be obvious .

What makes you say that? Visible light from the Sun reflecting off of objects is how we see them.

[guest39538]

Given that he has stated light is reflected so that you can see the surface, why do you not think it would be visible wavelngth light?

 Quite clearly because we can see the water.   

[guest39538]

It is not a wave-length between 400-700nm that is for sure, that should be obvious .

What makes you say that? Visible light from the Sun reflecting off of objects is how we see them.

We only see with our eyes things that have visible light between 400 - 700 nm,   400 - 700 nm having colour, the water has no colour but we can see it,   so if we can see it , it must be reflecting visible light in a wave-length other than 400-700nm.

[Kryptid]

It is not a wave-length between 400-700nm that is for sure, that should be obvious .

What makes you say that? Visible light from the Sun reflecting off of objects is how we see them.

We only see with our eyes things that have visible light between 400 - 700 nm,   400 - 700 nm having colour, the water has no colour but we can see it,   so if we can see it , it must be reflecting visible light in a wave-length other than 400-700nm.

That's called white light, which is a mixture of all the colors of light.

[guest39538]

It is not a wave-length between 400-700nm that is for sure, that should be obvious .

What makes you say that? Visible light from the Sun reflecting off of objects is how we see them.

We only see with our eyes things that have visible light between 400 - 700 nm,   400 - 700 nm having colour, the water has no colour but we can see it,   so if we can see it , it must be reflecting visible light in a wave-length other than 400-700nm.

That's called white light, which is a mixture of all the colors of light.

No it is not white light, it is clear , I can see white and it is different than clear.   White light is a mixture of frequencies I would not disagree, but the light  permeating between objects is not white .

[Kryptid]

No it is not white light, it is clear , I can see white and it is different than clear.   White light is a mixture of frequencies I would not disagree, but the light  permeating between objects is not white .

Very well, if you want to be technical about it. Still, when light of all different visible frequencies reaches your eyes, your brain interprets that as white. That's what's happening when sunlight reflects off of water. Water reflects light of all visible frequencies.

[guest39538]

No it is not white light, it is clear , I can see white and it is different than clear.   White light is a mixture of frequencies I would not disagree, but the light  permeating between objects is not white .

Very well, if you want to be technical about it. Still, when light of all different visible frequencies reaches your eyes, your brain interprets that as white. That's what's happening when sunlight reflects off of water. Water reflects light of all visible frequencies.

LOl, no it is does not,   water is not white either.   Let me explain why you can see the raindrop , the surroundings allow you to see the raindrop, the raindrop distorts your line of sight,  you see the sky and clouds through the raindrop. 

At night you can't see the raindrop, because the sky is dark . 

Try to understand that lensing is the raindrop distorting the light.

[Kryptid]

LOl, no it is does not,   water is not white either.   Let me explain why you can see the raindrop , the surroundings allow you to see the raindrop, the raindrop distorts your line of sight,  you see the sky and clouds through the raindrop. 

At night you can't see the raindrop, because the sky is dark . 

Try to understand that lensing is the raindrop distorting the light.

Yes, the light distortion is part of the reason you can see water. Although water is not opaque like white paint, it still does have a finite reflectivity and does reflect at least some portion of the light that strikes its surface. Otherwise, you wouldn't be able to see your reflection in the water.

I guess this thread has stopped being about black holes now?

[guest39538]

LOl, no it is does not,   water is not white either.   Let me explain why you can see the raindrop , the surroundings allow you to see the raindrop, the raindrop distorts your line of sight,  you see the sky and clouds through the raindrop. 

At night you can't see the raindrop, because the sky is dark . 

Try to understand that lensing is the raindrop distorting the light.

Yes, the light distortion is part of the reason you can see water. Although water is not opaque like white paint, it still does have a finite reflectivity and does reflect at least some portion of the light that strikes its surface. Otherwise, you wouldn't be able to see your reflection in the water.

I guess this thread has stopped being about black holes now?

Not at all, lensing is light related, we have discussed the distortion of light.   

A BH is either

1) opaque and dark in colour

2) transparent and clear in colour ( such as a field).

[Kryptid]

A BH is either

1) opaque and dark in colour

2) transparent and clear in colour ( such as a field).

Light can't pass through a black hole, so option number one is correct.

[guest39538]

A BH is either

1) opaque and dark in colour

2) transparent and clear in colour ( such as a field).

Light can't pass through a black hole, so option number one is correct.

Why can't light pass through a BH?   Surely both options give the same appearance, 

a dark opaque object would absorb light surely? 

[Kryptid]

Why can't light pass through a BH?   Surely both options give the same appearance, 

a dark opaque object would absorb light surely? 

Its gravity is too strong to allow any light to escape that crosses its event horizon.

[guest39538]

Why can't light pass through a BH?   Surely both options give the same appearance, 

a dark opaque object would absorb light surely? 

Its gravity is too strong to allow any light to escape that crosses its event horizon.

Interesting, but surely if that was the case, BH's would be showing up as hot spots all over the Universe?   

+hf/S=>T   


It can't gain without loss and not gain temperature.

[Kryptid]

Interesting, but surely if that was the case, BH's would be showing up as hot spots all over the Universe?   

+hf/S=>T   

Heat cannot get out of their event horizon either.

[guest39538]

Interesting, but surely if that was the case, BH's would be showing up as hot spots all over the Universe?   

+hf/S=>T   

Heat cannot get out of their event horizon either.

Then in time they might turn super nova?

Can we look at Bh's in being a dark star?

[Kryptid]

Then in time they might turn super nova?

Explosions can't escape the horizon. The late Stephen Hawking showed that quantum processes at the event horizon, however, can allow a black hole to "evaporate" over time: https://en.wikipedia.org/wiki/Hawking_radiation

Can we look at Bh's in being a dark star?

Interestingly enough, "dark star" is actually one of the earliest phrases used to describe what would eventually become known as a black holes. The assumptions behind a dark star were a little different, however, because only Newtonian mechanics were known at the time. They were assumed to be solid objects and the concept of an event horizon had not yet been discovered. Light would travel up a certain distance from their surface before inevitably being pulled back down again. This would allow you to see a dark star's emitted light if you were close enough to it (in contrast to relativity's black holes, which do not let light out of their horizons at all).

[guest39538]

Then in time they might turn super nova?

Explosions can't escape the horizon. The late Stephen Hawking showed that quantum processes at the event horizon, however, can allow a black hole to "evaporate" over time: https://en.wikipedia.org/wiki/Hawking_radiation

Can we look at Bh's in being a dark star?

Interestingly enough, "dark star" is actually one of the earliest phrases used to describe what would eventually become known as a black holes. The assumptions behind a dark star were a little different, however, because only Newtonian mechanics were known at the time. They were assumed to be solid objects and the concept of an event horizon had not yet been discovered. Light would travel up a certain distance from their surface before inevitably being pulled back down again. This would allow you to see a dark star's emitted light if you were close enough to it (in contrast to relativity's black holes, which do not let light out of their horizons at all).

Could it be possible that a BH does emit light, but at a frequency we cannot yet detect?

[Kryptid]

Could it be possible that a BH does emit light, but at a frequency we cannot yet detect?

Technically, Hawking radiation would be just that. For most black holes, the radiation emitted is so weak that we wouldn't detect it. However, that's coming from outside of the horizon, not inside of it.