What is that indicator/math symbol?

[Arup Biswas]

Some sort of hazziness inside a circle ..name of that??

 

[Drakkith]

Theta?

Edit: https://en.wikipedia.org/wiki/Theta

 

[fresh_42]

Theta?

Edit: https://en.wikipedia.org/wiki/Theta

And it's only made to let English native speakers look bad, as it is no "th" but originally pronounced as "teta", and of course with an "eh", not an "e".

 

[Drakkith]

And it's only made to let English native speakers look bad, as it is no "th" but pronounced as "teta", and of course with an "eh", not an "e".

Err, what?

 

[George Jones]

It is an uppercase theta; you are probably mores used to seeing a lowercase theta.

 

[fresh_42]

Err, what?

Ancient Greek: θῆτα thē̂ta [tʰɛ̂ːta]

 

[Drakkith]

Ancient Greek: θῆτα thē̂ta [tʰɛ̂ːta]

Oh, you're just saying it was originally pronounced differently than we do now.

 

[TeethWhitener]

The Greek-Americans that I asked pronounce it "thita," rhyming with "pita" but enunciating the t.

 

[Arup Biswas]

Isberg and Resnick really confuses me [emoji24] He could use beta,gamma or anything, instead of this uppercase theta [emoji26]

 

[mfb]

As this is in the context of radioactivity, alpha beta or gamma would be a problematic choice, and you probably want to keep delta for delta-electrons as well. $\theta$ for angles is quite common,no idea why that text uses $\Theta$.

 

[fresh_42]

Oh, you're just saying it was originally pronounced differently than we do now.

Yes, but whether one pronounces it in modern Greek, with an "[ i ]" or in ancient Greek with an "[ e ]", the "th" is wrong, as it is the Greek version of a "t" which is pronounced as a "t". Perhaps I should start and say the Steelers are from Pittsborough ...
Edit: I might have been wrong here, as the Greek have a sound [$t^h$] which is closer to "th" than to "t", something as in "theft". I had forgotten that there is also the $\tau$ for "t".

The Greek-Americans that I asked pronounce it "thita," rhyming with "pita" but enunciating the t.

Yes, but modern Greek is a bit different from the ancient language.

 

[fresh_42]

Isberg and Resnick really confuses me [emoji24] He could use beta,gamma or anything, instead of this uppercase theta [emoji26]

We usually loot every alphabet we can get a hand on $a,b,c,\ldots , \alpha,\beta,\gamma,\ldots , \mathfrak{a},\mathfrak{g},\mathfrak{h},\ldots, \mathbb{C},\mathbb{F},\mathbb{N},\ldots ,\mathcal{A},\mathcal{B},\mathcal{C},\ldots , \mathscr{A},\mathscr{B},\mathscr{C}$
that it makes me wonder why we don't use и , я , ч , etc.

 

[mfb]

Cyrillic needs more love.

 

[Mark44]

We usually loot every alphabet we can get a hand on $a,b,c,\ldots , \alpha,\beta,\gamma,\ldots , \mathfrak{a},\mathfrak{g},\mathfrak{h},\ldots, \mathbb{C},\mathbb{F},\mathbb{N},\ldots ,\mathcal{A},\mathcal{B},\mathcal{C},\ldots , \mathscr{A},\mathscr{B},\mathscr{C}$
that it makes me wonder why we don't use и , я , ч , etc.

Don't forget the Hebrew letter aleph ($\aleph$), as in $\aleph_0, \aleph_1$ and so on.

 

[Larry Boemler]

Arabic has some interesting letters. Too many important symbols have a wide variety of meanings