In the E-Reader Era, a Book a Year Is Slacking

[murraypaul]

Originally Posted by Sil_liS

Then there is the fact that we cannot discard the year as a unit of measure, since the distances between stars and galaxies are best described by lightyears.

That is circular reasoning. The only reason we use lightyears is because we measure time in years. If we measured time only in hours, we'd use lighthours instead.

[Sil_liS]

Originally Posted by murraypaul

That is circular reasoning. The only reason we use lightyears is because we measure time in years. If we measured time only in hours, we'd use lighthours instead.

We are measuring time in years and days and hours and minutes and seconds. The choice of describing the distances between stars and galaxies by lightyears has to do with the order of magnitude of the unit of measure. The terms lightday and lighthour and lightsecond are also used, but they are not the best choice for measuring the distance between galaxies.

How do you suppose that we wouldn't measure time in years? Do you assume that we would have no desire to determine the time necessary for our planet to go around the sun?

[murraypaul]

Originally Posted by Sil_liS

We are measuring time in years and days and hours and minutes and seconds. The choice of describing the distances between stars and galaxies by lightyears has to do with the order of magnitude of the unit of measure. The terms lightday and lighthour and lightsecond are also used, but they are not the best choice for measuring the distance between galaxies.

Nor are lightyears, which is why they are used more in science fiction than in reality. The parsec is the preferred unit.

How do you suppose that we wouldn't measure time in years? Do you assume that we would have no desire to determine the time necessary for our planet to go around the sun?

I made no comment either way about the initial argument, just that having to use years so that we can use lightyears is not a good reason.

[Sil_liS]

Originally Posted by murraypaul

Nor are lightyears, which is why they are used more in science fiction than in reality. The parsec is the preferred unit.

So this or this website are science fiction? What about NASA? I would give you links to articles, but you would have to pay to view them.

Originally Posted by murraypaul

I made no comment either way about the initial argument, just that having to use years so that we can use lightyears is not a good reason.

I didn't say that we have to use years to use lightyears. The use of candela as the unit for luminous intensity would not depend on people using candles as a light source. I said that would still use lightyears, so the concept of a year would still exist and there would be no reason to discard it from expressing the age of a person.

I also said that if we didn't use lightyears, we could get an unit of measure for time appropriate for measuring the age of a person from the alternative to lightyear. If you want to use parsecs to measure the distance, then you can have a unit of measure for the time it takes a photon to travel the distance of a parsec (3.26 Earth years). This would still be a better choice than hours to express the age of a person.

[Jadon]

Originally Posted by Sil_liS

How do you suppose that we wouldn't measure time in years? Do you assume that we would have no desire to determine the time necessary for our planet to go around the sun?

We might not, depending on various things. If you live on a planet with a very short or long year, its year may be of little convenient use to you. If your friends come from various planets, you deal with years of different lengths, so having to specify which year you mean, or use a standard one which doesn't agree with any of yours, may be inconvenient. You may not live on a planet at all, but instead reside permanently on a ship, or in a system with only planetoid belts, or whatever.

Some science fiction works have used metric seconds, instead. (The Outcasts of Heaven Belt by Joan D. Vinge, for example.) "I'll be done in a kilosecond" or a megasecond-long vacation. My brother had a party when he hit a gigasecond.

[murraypaul]

Originally Posted by Sil_liS

So this or this website are science fiction? What about NASA? I would give you links to articles, but you would have to pay to view them.

The word 'more' is not a synonym for 'only'.

[murraypaul]

Originally Posted by Jadon

We might not, depending on various things. If you live on a planet with a very short or long year, its year may be of little convenient use to you.

At the other end of the scale, I would think that in primitive societies, the lunar month would be a much more useful unit, as it can be easily counted by anyone.

[QuantumIguana]

Year, month and day are all one syllable long. Hour and second are two syllables long (hour is sort of in between one and two syllables). I don't think that is coincidence. The terms we use the most tend to be short. Cat, dog, pig, horse, fish, sheep, etc.

[Sil_liS]

Originally Posted by Jadon

We might not, depending on various things. If you live on a planet with a very short or long year, its year may be of little convenient use to you. If your friends come from various planets, you deal with years of different lengths, so having to specify which year you mean, or use a standard one which doesn't agree with any of yours, may be inconvenient. You may not live on a planet at all, but instead reside permanently on a ship, or in a system with only planetoid belts, or whatever.

If you think like that then timezones must seem like an inconvenience as well. And don't get me started on the daylight savings time.

Originally Posted by murraypaul

The word 'more' is not a synonym for 'only'.

You are right, it's not. From what I have seen the preferred term is light-year, but this was not the best way to express this. I'll try another way:
google "site:nasa.gov parsec" 6,570 results
google "site:nasa.gov light-year -buzz" 42,000 results (the "-buzz" is to exclude Buzz Lightyear from the results)

Springerlink.com is a website where you can find scientific journals.
google "site:springerlink.com parsec" 1,820 results
google "site:springerlink.com light-year" 595,000 results

What makes you think that parsec is used more than lightyear in reality?

Originally Posted by murraypaul

At the other end of the scale, I would think that in primitive societies, the lunar month would be a much more useful unit, as it can be easily counted by anyone.

And yet people seem to have agreed that using the seasons (and therefore the year) is a better way to tell the passage of time.

[murraypaul]

Originally Posted by Sil_liS

What makes you think that parsec is used more than lightyear in reality?

That isn't actually what I said.

In response to your statement:

The terms lightday and lighthour and lightsecond are also used, but they are not the best choice for measuring the distance between galaxies.

I made three assertions:
a) Light-year was also not the best choice for measuring distance between galaxies
b) Light-year is used more in science fiction than in reality
c) Parsec is the preferred unit (for measuring distance between galaxies)

And for the latter, as you accept NASA as a source:
http://heasarc.nasa.gov/docs/cosmic/milkyway_info.html

Although the light year is a commonly used unit, astronomers prefer a different unit called the parsec (pc).

International Astronomical Union:
http://www.iau.org/public/measuring/

Beyond the Solar System the distances in astronomy are so great that using the AU becomes too cumbersome. The IAU recognises several other distance units to be used on different scales. For studies of the structure of the Milky Way, our local galaxy, the parsec (pc) is the usual choice. This is equivalent to about 30.857×1012 km, or about 206,000 AUs, and is itself defined in terms of the AU – as the distance at which one Astronomical Unit subtends an angle of one arcsecond. Alternatively the light-year (ly) is sometimes used in scientific papers as a distance unit, although its use is mostly confined to popular publications and similar media. The light-year is roughly equivalent to 0.3 parsecs, and is equal to the distance traveled by light in one Julian year in a vacuum, according to the IAU. To think of it in easily accessible terms, the light-year is 9,460,730,472,580.8 km or 63,241 AU. While smaller than the parsec, it is still an incredibly large distance.

[QuantumIguana]

When NASA communicates with the public, they nearly always use light-years rather than parsecs. Thus, it is not true that light-years is used more in science fiction than in reality. What astrometrics uses is only part of reality.

[Sil_liS]

Originally Posted by murraypaul

I made three assertions:
a) Light-year was also not the best choice for measuring distance between galaxies
b) Light-year is used more in science fiction than in reality
c) Parsec is the preferred unit (for measuring distance between galaxies)

And for the latter, as you accept NASA as a source:
http://heasarc.nasa.gov/docs/cosmic/milkyway_info.html


International Astronomical Union:
http://www.iau.org/public/measuring/

It seems that you missed something in the quote:

Beyond the Solar System the distances in astronomy are so great that using the AU becomes too cumbersome. The IAU recognises several other distance units to be used on different scales. For studies of the structure of the Milky Way, our local galaxy, the parsec (pc) is the usual choice. This is equivalent to about 30.857×1012 km, or about 206,000 AUs, and is itself defined in terms of the AU – as the distance at which one Astronomical Unit subtends an angle of one arcsecond. Alternatively the light-year (ly) is sometimes used in scientific papers as a distance unit, although its use is mostly confined to popular publications and similar media. The light-year is roughly equivalent to 0.3 parsecs, and is equal to the distance traveled by light in one Julian year in a vacuum, according to the IAU. To think of it in easily accessible terms, the light-year is 9,460,730,472,580.8 km or 63,241 AU. While smaller than the parsec, it is still an incredibly large distance.

There is a reason why I'm pointing this out:
The name parsec is "an abbreviated form of 'a distance corresponding to a parallax of one second'".

Trigonometric parallax--the tiny, apparent back-and-forth shifts of nearby stars caused by our changing perspective as the earth orbits the sun--can indeed be used to measure distances only to comparatively nearby stars.

Notice the "only".

When it comes to galaxies:
In the 1920s Edwin Hubble used the period-luminosity relation for variable stars to establish the distances to various galaxies and proved that they lie far outside our Milky Way. In the course of that work, he discovered what we now call 'Hubble's law,' that galaxies display a linear relation between distance and redshift (the redshift is the shift in the positions of lines in the galaxies' spectra toward the red end of the rainbow). Hubble's law is the basis for the modern understanding that we live in an expanding universe. After measuring the redshift, which we can do by passing a galaxy's light through a spectrogram, we can deduce the distance using Hubble's law. This technique is the astronomer's basic tool for finding the distances to the farthest things in the universe.

The reason why using light-year makes sense is because when you say that a galaxy is 13.2 billion light years from Earth, it means that the image that we get is the image of how the galaxy looked like 13.2 billion light-years ago.


And can you tell me the basis for this assertion: b) Light-year is used more in science fiction than in reality.

[Steven Lyle Jordan]

For awhile I was putting out 2 books in about 15-18 months, which was an easy pace for me. (Let's not get into comparing me to other authors or their quality, please.) It seems the most I got out of it was greater name-recognition while I had new works available... the quality of the work did not decline as I produced more books per year (if anything, it may have increased).

Presently, I haven't written anything new in over a year (as I've been re-proofing older books), and as a result, my name recognition has dropped, and so have my sales.

There's something to be said for concentrating on other aspects of your profession, such as marketing or exploring other markets. But clearly your audience (assuming you have one of those) cares nothing for that. Therefore, if they want you to write, and they'll pay for your books, you might as well write and make them happy.

But don't rush it. I could probably turn out three books a year, but they'd be crappy. That is not the way.

[murraypaul]

Originally Posted by Sil_liS

And can you tell me the basis for this assertion: b) Light-year is used more in science fiction than in reality.

I'm not sure I've ever seen parsec used in science-fiction, and if it is used at all, its used is overwhelmed by the use of light-years. In reality, both light-years and parsec are used.

[murraypaul]

Originally Posted by Sil_liS

There is a reason why I'm pointing this out:
The name parsec is "an abbreviated form of 'a distance corresponding to a parallax of one second'".

Trigonometric parallax--the tiny, apparent back-and-forth shifts of nearby stars caused by our changing perspective as the earth orbits the sun--can indeed be used to measure distances only to comparatively nearby stars.

Notice the "only".

The parsec was defined based on a calculation of a parallex of 1 arc second at the distance of the sun, but that has nothing to do with the measurement of the distance between two objects, and you don't measure parallex to calculate that distance. In the same way that the kilo was defined as the mass of 1 litre of water, but you don't measure people's weight by comparing them to volumes of water.
A parsec is a distance of 30.857×10^12 km.