probable distance from Urth to Bleen

Jerry Friedman · 03 Dec 2002, 00:26 · from urth-v0212.mbox · original

This is the message as the crawl holds it, before anything here touched it. What the conversation shows has been through ingest: transfer encodings decoded, attachments dropped, quote markers repaired, and the archiver’s ? resolved into quotation marks and dashes. Those repairs are judgements and some of them are wrong, which is what this page is for. Email addresses are obscured here as they are everywhere else on the site, so it is before our repairs rather than byte for byte.

From: Jerry Friedman <jerry_friedman at yahoo.com>
Subject: RE: (urth) probable distance from Urth to Bleen
Date: Mon, 2 Dec 2002 16:26:41 -0800 (PST)
Message-ID: <urth-v0212-2333 at digest.urth.net>
X-Urthmirror-Source: http://www.urth.net/urth/archives/v0212/2333.txt.shtml
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printable

--- Dan'l Danehy-Oakes <ddanehy at siebel.com> wrote:
> > Um, no, Jerry . . . when the Whorl is at rest, the Whorl=20
> > people experience time at the same flow as people on Urth or=20
> > Blue or Green, but at near-light speeds subjective time (the=20
> > passage of time experienced by the crew) is compressed=20
> > compared to the objective time of the rest of the universe=20
> > (or technically "any other location that is not accelerated=20
> > to NAFAL velocities," which happens to encompass most of the=20
> > universe).

This "technically" comment is more nearly correct than your
"subjective" and "objective" comments.  You're forgetting the
expansion of the universe, though.  To be nit-pickingly correct,
a great deal of the matter in the universe *is* moving at
relativistic velocities in our reference frame.  So your "any
other location" happens to encompass our galaxy, indeed our
local supercluster and much more, but not the whole universe.

> > This is the basis of the famous "twin paradox." =20
> > (I'm not coining the use of "objective" and "subjective"=20
> > here: that is how it is done.)  Look into it, if you like,=20
> > since it is fascinating!  Or just take my word for it.
>=20
> Um, no, Mantis ... in a world that obeys Einstein's rules,=20
> "time" is equally [ob|sub]jective in any inertial reference
> frame; more specifically, "time" on the Whorl cruising at
> NAFAL velocities is no more and no less objective than "time"=20
> on the surface of Urth. This is a consequence of "time" not=20
> being an independent entity in such a world; it is one=20
> dimension of a four-or-more-dimensional manifold which we=20
> (more) properly refer to as "spacetime."
>=20
> The "objective time"/"subjective time" terminology you use
> comes, not from relativistic physics, but from SF writers=20
> who play with these concepts in their novels but either=20
> do not comprehend what I oversimplify in the previous
> paragraph, or else assume (and I think this quite likely)
> that most "users" of NAFAL ships would think this way, the
> non-absolute nature of spacetime in an Einsteinian universe
> being kind of difficult to wrap one's head around. (I do
> not claim to have my head all the way around it by any
> means!)=20

Thanks, Blattid.  I probably shouldn't mention that I have a
Ph. D. in physics, since then people might stop arguing with me
about physics, and as my students could tell you, I do make
mistakes.

There's an interesting and comprehensible discussion of the twin
paradox at <http://tinyurl.com/3648>.  It contains the comment,
'Relativity here pays the price of permissiveness. It says to us,
"Pick whichever frame you like to describe your results, or use
spacetime diagrams and don't choose a reference frame at all.
They're all equivalent, I don't mind."  No wonder that one
explanation ends up looking like three or four.'

And nothing saying that one reference frame is subjective and
another is objective.

Jerry Friedman

__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com

--=20

An unofficial mirror of a public mailing list · about & removal requests · download the archive · before the list · original archive at urth.net