Why "even light"?

[Genady]

10 minutes ago, md65536 said:

The phrase "not even light can escape a black hole" is correct. Do you find it confusing? The statement doesn't imply that light is expected to escape from everything, or that if IT cannot escape then NOTHING can, and I doubt many others have that confusion.

What is unclear to me is a role of the word "even" in it.

[StringJunky]

14 minutes ago, Genady said:

What is unclear to me is a role of the word "even" in it.

In this instance, it means including phenomena that a layman would not normally consider part of it. It's a kind of rhetorical interjection intended to surprise the layman reader. "Ooh...did you know that it includes light as well?"

Edited August 3, 2023 by StringJunky

[md65536]

24 minutes ago, Genady said:

What is unclear to me is a role of the word "even" in it.

Typically laypeople would think of inability to escape in terms of strong gravity and its effect on masses, so it is reasonable to emphasize that it also applies to light. I don't think the writers needed to worry, "this word might confuse people who already understand this."

 

Edited August 3, 2023 by md65536

[MJ kihara]

1 hour ago, exchemist said:

Experience: people that can't communicate coherently often can't think coherently, I have found. 

What's your area of expertise? If your a doctor I would want to know about that from you...having attitudes and stereotyping is not thinking coherently....you haven't talked anything substantial about light escaping from blackhole or are you coming up with a new way to communicate concept of relativity that am not deciphering...I need help here pliz...😂.

6 hours ago, Genady said:

If this is the case, then the comparison to light is simply wrong, because one does not need a high velocity to escape a Newtonian BH. One could just crawl out of it.

How is it possible to crawl out of a  Blackhole...of course Newtonian BH?

[StringJunky]

22 minutes ago, MJ kihara said:

What's your area of expertise? If your a doctor I would want to know about that from you...having attitudes and stereotyping is not thinking coherently....you haven't talked anything substantial about light escaping from blackhole or are you coming up with a new way to communicate concept of relativity that am not deciphering...I need help here pliz...😂.

How is it possible to crawl out of a  Blackhole...of course Newtonian BH?

He's asking about a particular word usage, not the subject itself.

[Genady]

31 minutes ago, md65536 said:

Typically laypeople would think of inability to escape in terms of strong gravity and its effect on masses, so it is reasonable to emphasize that it also applies to light. I don't think the writers needed to worry, "this word might confuse people who already understand this."

 

Perhaps so, I don't know. In my mind, a much more powerful emphasis of how strong the gravity of BH is, would be a phrase, e.g., "nothing, even a spacecraft with an infinitely powerful engine, can't escape it."

32 minutes ago, MJ kihara said:

How is it possible to crawl out of a  Blackhole...of course Newtonian BH?

As I said here, https://www.scienceforums.net/topic/132131-why-even-light/?do=findComment&comment=1246405,

"A powered spacecraft, a ladder, a tower, a rope hanging from an orbiting spacecraft, etc."

[swansont]

14 minutes ago, Genady said:

Perhaps so, I don't know. In my mind, a much more powerful emphasis of how strong the gravity of BH is, would be a phrase, e.g., "nothing, even a spacecraft with an infinitely powerful engine, can't escape it."

I think the average layperson thinks light is unaffected by gravity.

[exchemist]

 

46 minutes ago, MJ kihara said:

What's your area of expertise? If your a doctor I would want to know about that from you...having attitudes and stereotyping is not thinking coherently....you haven't talked anything substantial about light escaping from blackhole or are you coming up with a new way to communicate concept of relativity that am not deciphering...I need help here pliz...😂.

 

My profile is visible if you care to look it up.

I answered the thread OP in post 2 as clearly as I was able. (I did include a joke, mind you.)

[MJ kihara]

26 minutes ago, StringJunky said:

He's asking about a particular word usage, not the subject itself.

got it.

50 minutes ago, MJ kihara said:

2 hours ago, exchemist said:

Experience: people that can't communicate coherently often can't think coherently, I have found. 

What's your area of expertise? If your a doctor I would want to know about that from you...having attitudes and stereotyping is not thinking coherently....you haven't talked anything substantial about light escaping from blackhole or are you coming up with a new way to communicate concept of relativity that am not deciphering...I need help here pliz...😂.

This was a follow up for-exchemist comment.

28 minutes ago, Genady said:

As I said here, https://www.scienceforums.net/topic/132131-why-even-light/?do=findComment&comment=1246405,

"A powered spacecraft, a ladder, a tower, a rope hanging from an orbiting spacecraft, etc."

In such a case does the Blackhole in question have a singularity?

[Genady]

12 minutes ago, MJ kihara said:

In such a case does the Blackhole in question have a singularity?

Newtonian BH does not have singularity.

28 minutes ago, swansont said:

I think the average layperson thinks light is unaffected by gravity.

But if they think that light is unaffected by gravity, then how does the black hole's effect on light emphasize its gravity?

[StringJunky]

54 minutes ago, Genady said:

Newtonian BH does not have singularity.

But if they think that light is unaffected by gravity, then how does the black hole's effect on light emphasize its gravity?

"It is so strong, it can pull on light as well as matter". This is not a level of educating where you would be mentioning extreme curvature as the proper reason.

Edited August 3, 2023 by StringJunky

[zapatos]

As a layman it is obvious to me that as mass increases it becomes harder to get something off the surface of a body. I can easily toss a ball in the air. A bowling ball is harder. Imagine launching a boulder. To launch a spaceship requires a massive amount of brains and energy. Yet I can flip on my $2 flashlight with a flick of my finger and see the light beam instantly move up the side of the building and into space. Light readily leaves something as massive as the sun. I have absolutely no experience where light seems to be held back. It seems gravity cannot hold it back, nor does gravity even have any affect on it.

So when someone says "Even light cannot escape!", I  think "WOW! That is AMAZING!!" Light ALWAYS escapes!! (in my experience) "The amount of gravity in a black hole must be something really extreme. And as an afterthought, I guess that is why it is called 'black'."

[Genady]

3 hours ago, md65536 said:

The statement doesn't imply that light is expected to escape from everything

Aha! To somebody, it does:

14 minutes ago, zapatos said:

So when someone says "Even light cannot escape!", I  think "WOW! That is AMAZING!!" Light ALWAYS escapes!! (in my experience)

 

[md65536]

34 minutes ago, Genady said:

Aha! To somebody, it does:

 

The expectation that light ALWAYS escapes comes from "in my experience" here, not from the statement "Even light cannot escape!" At best the statement acknowledges that it might be expected that light wouldn't escape, not that it must be expected.

But that justifies inclusion of "even light". I think it's more likely that someone already expects that light should escape, and the statement corrects that common(?) misconception, rather than that someone doesn't think that light is expected to escape until after reading the statement.

 

This doesn't really matter though. The statements including "even" are correct, and succinct. I think it's a good way to describe black holes. I think it's useful for beginners to understand that BHs involve spacetime curvature, and I think it's unlikely that anyone who already understands is going to be misled by the word "even".

Edited August 3, 2023 by md65536

[Genady]

4 minutes ago, md65536 said:

The expectation that light ALWAYS escapes comes from "in my experience" here, not from the statement "Even light cannot escape!" At best the statement acknowledges that it might be expected that light wouldn't escape, not that it must be expected.

But that justifies inclusion of "even light". I think it's more likely that someone already expects that light should escape, and the statement corrects that common(?) misconception, rather than that someone doesn't think that light is expected to escape until after reading the statement.

But that was exactly what I meant in the OP when I wrote, "as if light is expected to escape from everything" (bold emphasis added).

Anyway, I think this phrase is just a popular cliché. I've conducted a little experiment five minutes ago. I've asked ChatGPT for a short description of black hole. Of course, its answer represents common patterns in these descriptions. And the first sentence is,

Quote

A black hole is a region in space where the gravitational force is so intense that nothing, not even light, can escape from it.

 

[MJ kihara]

3 hours ago, zapatos said:

So when someone says "Even light cannot escape!", I  think "WOW! That is AMAZING!!" Light ALWAYS escapes!! (in my experience) "The amount of gravity in a black hole must be something really extreme. And as an afterthought, I guess that is why it is called 'black'."

That was exactly what I thought when i first came across that expression...it gave me the urge to understand more...up to now...I had to spend seven year to go through internet materials to the level of coming up with a theory that someone of nature...layman...when he reads it to spend much less time to internalize the issues of gravity....and I think it works,since when I start short conversations with my friends(you know if am a layman...then they are strawmen) here about it and afterwards they start asking interesting questions some at par with question I see across... reasonable than from crackpots.

3 hours ago, md65536 said:

I think it's useful for beginners to understand that BHs involve spacetime curvature, and I think it's unlikely that anyone who already understands is going to be misled by the word "even".

Curvature-from my perspective come with geometric explanations that can be difficult to relate to initially to nature, for beginners.for instance relating right triangles with spacetime intervals,yet when i look at the skies(space) i don't see triangles...and further complicating things when it come to time dilation and length contraction....the beginner heads(of course depending on how hard it is) start spinning alot...I was once in such situations esp with just introductory elementary physics background...and it feels embarrassing sometimes to know they are critical issues of nature and universe that someone can't comprehend and yet it seem obvious to others(physicist).

3 hours ago, Genady said:

Anyway, I think this phrase is just a popular cliché. I've conducted a little experiment five minutes ago. I've asked ChatGPT for a short description of black hole. Of course, its answer represents common patterns in these descriptions. And the first sentence is,

 

What does it says about about spacetime curvature?

[md65536]

4 hours ago, Genady said:

Anyway, I think this phrase is just a popular cliché.

 

I think it's more useful to include it than not to. It's not just aimed at people who expect light to escape from everything, but also those who wouldn't even consider that light might be related at all. That light--specifically--can't escape a black hole is a huge part of an average lay understanding of black holes.

[Genady]

31 minutes ago, md65536 said:

That light--specifically--can't escape a black hole is a huge part of an average lay understanding of black holes.

I don't know if there are data to support this statement, but I'm ready to believe it. I am ready to believe it, because this phrase is repeated so often, that if they remember anything about black holes, then they remember it.

[md65536]

4 hours ago, Genady said:

I don't know if there are data to support this statement, but I'm ready to believe it. I am ready to believe it, because this phrase is repeated so often, that if they remember anything about black holes, then they remember it.

Here's a few people you could ask if that's why they used the phrase:

"within a certain region of space around it — nothing can escape its gravitational pull. Inside what's known as the black hole's event horizon, not even light itself can escape from a black hole." -- Ethan Siegel https://www.forbes.com/sites/startswithabang/2020/03/24/sorry-stephen-hawking-but-every-black-hole-is-still-growing-not-decaying/

'Physical objects (those that move at or more slowly than the speed of light) can pass through the “event horizon” that defines the boundary of the black hole, but they never escape back to the outside world. Black holes are therefore black — even light cannot escape — thus the name.' -- Sean Carroll https://www.preposterousuniverse.com/blog/2020/11/26/thanksgiving-15/

"Ultimately, when the star has shrunk to a few tens of kilometers size, its gravity grows so enormous that nothing, not even light, can escape its grip. The star creates a black hole around itself." -- Kip Thorne https://www.its.caltech.edu/~kip/scripts/PubScans/BlackHoles-Thorne-Starmus.pdf

Incidentally, I first looked up Misner, Thorne, Wheeler - Gravitation thinking they might have used the phrase there, and they didn't, and I couldn't find a case where Hawking used it either. The older descriptions of black holes introduced them as "collapsed stars", I guess because that was their only expected existence? They introduced them by describing the formation of the horizon, with a lot more to think about than just "nothing can escape (not even light!)". So I can see how that phrase is at least disappointing. However, I couldn't suggest an improvement, and I think simply omitting "even light" would be even less helpful.

 

Edited August 4, 2023 by md65536

[Genady]

4 hours ago, md65536 said:

However, I couldn't suggest an improvement, and I think simply omitting "even light" would be even less helpful.

I think that the emphasis on escaping is weak. They - bodies, light - not only cannot escape, but they also cannot make a move away from the BH center or even stay still. Everything necessarily keeps moving deeper and deeper into the BH.

It is not just about "light itself" (Ethan Siegel). It is about time itself. Beyond the event horizon, direction toward the center is the forward direction of time. Everything - even light  - moves forward in time, which means, toward the BH center.

[Genady]

16 hours ago, MJ kihara said:

What does it says about about spacetime curvature?

I think this question would be OT here.

[Steve81]

On 8/3/2023 at 3:22 PM, StringJunky said:

"It is so strong, it can pull on light as well as matter". This is not a level of educating where you would be mentioning extreme curvature as the proper reason.

Depends on the teacher. I’d use a suspended blanket and a series of progressively larger weights. A small weight would create a small depression in the blanket, and eventually you’d get to a point where a sufficiently massive weight would break the whole dang setup. Seems like a fair way to visualize it. Another fun way to put it, Black Holes = Hotel California. We are programmed to receive…but you can never leave.

Edited August 11, 2023 by Steve81

[Genady]

1 hour ago, Steve81 said:

Depends on the teacher. I’d use a suspended blanket and a series of progressively larger weights. A small weight would create a small depression in the blanket, and eventually you’d get to a point where a sufficiently massive weight would break the whole dang setup. Seems like a fair way to visualize it. Another fun way to put it, Black Holes = Hotel California. We are programmed to receive…but you can never leave.

The blanket exercise demonstrates a breaking point. What does it have to do with black holes though? I mean, you got the Earth, the weight, and the blanket. What does the blanket signify? What does a depression in the blanket signify? 

Regarding the Hotel California, I don't see any similarity with the black holes at all. You could just use a mousetrap instead.

[Steve81]

44 minutes ago, Genady said:

The blanket exercise demonstrates a breaking point. What does it have to do with black holes though? I mean, you got the Earth, the weight, and the blanket. What does the blanket signify? What does a depression in the blanket signify? 

Regarding the Hotel California, I don't see any similarity with the black holes at all. You could just use a mousetrap instead.

The blanket is a two dimensional representation of spacetime. The depression demonstrates how massive objects warp spacetime (gravity). With a black hole, this effect becomes so profound, it creates an inescapable pocket of space. At least that’s my rudimentary understanding.

Edited August 11, 2023 by Steve81

[Genady]

10 minutes ago, Steve81 said:

The blanket is a two dimensional representation of spacetime. The depression demonstrates how massive objects warp spacetime (gravity). With a black hole, this effect becomes so profound, it creates an inescapable pocket of space. At least that’s my rudimentary understanding.

I think that this demonstration is wrong for a number of reasons:

1. Blanket breaks. Spacetime does not.

2. The depression in the blanket is caused by weight of the object. A black hole is caused by its size.

3. The depression is caused not by the object's gravity, but by the Earth's gravity.

4. The blanket responds to the weight due to its elasticity. The spacetime does not.

...