Schwarzschild radius

[elas]

Indeed. The Fixler/Kasevich number is 6.693, with a standard error of 0.027 and a systematic error of 0.021, which means it's consistent with the other value, but not measured as precisely.

 

3 is the acceptable way of expressing 2.95, if you are only using one significant digit. Did Davies use this in a paper or a popular book or talk? I expect it's the latter

 

Thanks again, Davies did indeed quotes a value of three in 'The New Physics' a popular book obviously written to mislead amateurs like me!

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The following graph shows the Black Holes listed on:

http://www.johnstonsarchive.net/relativity/bhctable.html

Red and blue lines are the main and maximum error lines respectively.

Green line (second from top left) is the radius calculated from the Schwarzchild radius formula.

Red dash line is the radius calculated using the G constant.

The results are, unfortunately; inconclusive.

But I hope everyone who contributed to this forum will think the exercise worthwhile;

many thanks,

elas

Edited November 12, 2009 by elas
Consecutive posts merged.

[swansont]

What are you graphing? You need to label your graphs, otherwise they don't make much sense.

 

If it's mass vs radius, you'd better get a straight line, since the radius (and diameter) was probably just calculated from the mass. And scatter you find is from rounding, since only one or two digits was kept.

[elas]

What are you graphing? You need to label your graphs, otherwise they don't make much sense.

 

If it's mass vs radius, you'd better get a straight line, since the radius (and diameter) was probably just calculated from the mass. And scatter you find is from rounding, since only one or two digits was kept.

 

The three ways used to calculate the Black Hole radius are:

A) From the circumference given in the List of Black Holes.

B) Using the Schwarzschild radius equation.

C) Replacing the 2.95 constant of Black Hole radius equation with a constant (2.980727823) that equates with: r = G/m

The results show that in eleven cases B is closer to A than C and in nine cases C is close to A than B.

All of the twenty results fall well inside the margin of error given in the list.

The compilerof the list (Wm. Robert Johnston) does not say how the values for 'circumference' were obtained; the margin of error quoted above is that given for the mass values (converted to percentage values for use with r values).

Edited November 13, 2009 by elas

[Klaynos]

A) From the circumference given in the List of Black Holes.

 

How is that found?

 

Also, in the linked to list is teh mass not both the BH and the companion star?

[swansont]

How is that found?

 

Also, in the linked to list is teh mass not both the BH and the companion star?

 

The mass of the BH is given, with the mass of companion in parentheses.

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Merged post follows:

Consecutive posts merged

The three ways used to calculate the Black Hole radius are:

A) From the circumference given in the List of Black Holes.

B) Using the Schwarzschild radius equation.

C) Replacing the 2.95 constant of Black Hole radius equation with a constant (2.980727823) that equates with: r = G/m

The results show that in eleven cases B is closer to A than C and in nine cases C is close to A than B.

All of the twenty results fall well inside the margin of error given in the list.

The compilerof the list (Wm. Robert Johnston) does not say how the values for 'circumference' were obtained; the margin of error quoted above is that given for the mass values (converted to percentage values for use with r values).

 

Except that I suspect that A and B are actually the same, with the radius being calculated rather than empirically determined. The scatter you see is from rounding. Which makes the graph an exercise in plotting (ax) vs (x) and nothing more.

Edited November 13, 2009 by swansont
Consecutive posts merged.

[elas]

 

Except that I suspect that A and B are actually the same, with the radius being calculated rather than empirically determined. The scatter you see is from rounding. Which makes the graph an exercise in plotting (ax) vs (x) and nothing more.

 

Surely where there is no significant difference between the results of equations A, B and C and all fall well within the experimental margin of error; we should use the equation with the minimum number of factors or one that uses only factors relating to the entities being observed (i.e. mass and circumference).

Edited November 13, 2009 by elas