Infinitely small?

[Chuffy]

I'm watching a documentary about the Hubble space telescope. The chap presenting it has just used the phrase 'infinitely small'.

How can something be infinitely small? Surely there comes a point where the thing simply ceases to exist?

If anyone can explain this in terms which won't make my brain want to crawl under behind the sofa and cry I'd be very grateful.

 

[Noodley]

Explanation: Science for people who read the Mail

 

[Chuffy]

Explanation: Science for people who read the Mail

I'm not sure who should be more insulted, me or the bloke from the European Space Agency who was presenting the program.

 

[Noodley]

I'm not sure who should be more insulted, me or the bloke from the European Space Agency who was presenting the program.

He'll have been told what his audience would be and how to 'sex it up' with meaningless words.

You, on the other hand....

Ayway, X Factor has just come on. And Robbie is gonna be singing LIVE.


Time to go for a long bath.....

 

[Dayvo]

Time to go for a long bath.....

Have you got one, what with you being, er, tall for your height?

 

[marinyork]

There's no particular reason why something cannot be infinitely small. It is a possible difference between Maths and Physics. The universe is whatever it turns out to be though, who knows? However the view of infinitely small in physical sciences is that it usually stops at some point (for various arguments) or might as well. Basically infinitely small usually means if it does have any spatial extent it either doesn't matter or isn't measurable or both. In terms of the big bang, infinitely small means exactly what it says on the tin (ish).

I quickly found this http://www.science.doe.gov/bes/scale_of_things.html which has a nice table that you get the idea of things on the cell and atomic and above level. Things get so small that Physicists use the SI prefixes. Milli means a thousandth of a metre, micro a millionth, nano a billionth, pico a trillionth and so on. What is referred to as the classical electron radius (electrons are believed to be point particles) is about a million times smaller than anything in that diagram. Things can theoretically be about a sextillionth of the size of the classical electron radius.

 

[661-Pete]

Damn! Missed that programme (but it's a repeat, I think I saw it at first airing ).

'Infinitely small'? If we take that as equivalent to 'infinitesimal', then there's a sound mathematical basis for something which tends towards zero but never quite reaches it. Indeed we wouldn't get very far in science and technology without such a concept. Did none of you lot do calculus at school? Surely you remember the expression 'dx', representing an infinitesimally small increment in the variable 'x', but it can't be exactly zero or 'x' would never change!

But I don't know how they used the phrase in the HST programme. Possibly it is a case of 'popular science' stumbling over its own feet...

 

[Chuffy]

Damn! Missed that programme (but it's a repeat, I think I saw it at first airing ).

'Infinitely small'? If we take that as equivalent to 'infinitesimal', then there's a sound mathematical basis for something which tends towards zero but never quite reaches it. Indeed we wouldn't get very far in science and technology without such a concept. Did none of you lot do calculus at school? Surely you remember the expression 'dx', representing an infinitesimally small increment in the variable 'x', but it can't be exactly zero or 'x' would never change!

But I don't know how they used the phrase in the HST programme. Possibly it is a case of 'popular science' stumbling over its own feet...

No.

Er, thanks chaps. I think....

 

[661-Pete]

No.

Er, thanks chaps. I think....

Well, you asked for an explanation. I tried .

 

[Chuffy]

Well, you asked for an explanation. I tried .

That's ok Pete. I'm so near the back of the class with kind of stuff that I'm practically at the front.

 

[purplepolly]

How can something be infinitely small? Surely there comes a point where the thing simply ceases to exist?

If anyone can explain this in terms which won't make my brain want to crawl under behind the sofa and cry I'd be very grateful.

it's very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very small

 

[marinyork]

Well, you asked for an explanation. I tried .

Er, Pete, Calculus went off the "school" syllabus some time in the early-mid 80s.

Anyway I didn't see the programme. Presumably they were talking about "infinitely small" in terms of the big bang?

 

[Chuffy]

Er, Pete, Calculus went off the "school" syllabus some time in the early-mid 80s.

That's after I left.

Anyway I didn't see the programme. Presumably they were talking about "infinitely small" in terms of the big bang?

Black holes were being bandied about. Beards were being worn and quasars were mentioned.

 

[Davidc]

Won't argue with what MY has posted. There is another usage though.

Something which approaches (or tends to) infinitessimally small, (or anything divided by infinity, or zero), as another thing approaches a certain value can be said to become infinitessimally small.

The difference is a bit esoteric.

 

[solmisation]

That's ok Pete. I'm so near the back of the class with kind of stuff that I'm practically at the front.

If anyone tells you that you are as thick as two short planks, just inform them that

1 Planck length= 10-35 meters

not really that thick!