seeing the past

[FrogSplash]

I've been extremely interested in the search for the first galaxies and possibly the Big Event itself. I won't say big bang because it could be something else entirely.

My question is: If were seeing galaxies as they looked in the past. Could it be possible that were seeing our own galaxy too?

[neufer]

My question is: If were seeing galaxies as they looked in the past. Could it be possible that were seeing our own galaxy too?

Before we could possibly 'see ourselves' in the past we would probably have to see multiple images of other objects in the sky.

However, we don't yet see multiple images of other objects in the sky even using the Wilkinson Microwave Anisotropy Probe (WMAP):

<<If the observable universe encompasses the entire universe, one can determine the global structure by observation. Further, the universe could be small in some dimension and not in others (like a cylinder): if a small closed loop exists, one would see multiple images of objects in the sky.

Analysis of data from the Wilkinson Microwave Anisotropy Probe (WMAP) looks for multiple "back-to-back" images of the distant universe in the cosmic microwave background radiation. It may be possible to observe multiple images of a given object, if the light it emits has had sufficient time to make one or more complete circuits of a bounded universe. Current results and analysis do not rule out a bounded global geometry (i.e. a closed universe), but they do confirm that the spatial curvature is small, just as the spatial curvature of the surface of the Earth is small compared to a horizon of a thousand kilometers or so. If the universe is bounded, this does not imply anything about the sign or zeroness of its curvature.

Based on analyses of the WMAP data, cosmologists during 2004–2006 focused on the Poincaré dodecahedral space (PDS), but horn topologies (which are hyperbolic) were also deemed compatible with the data.>>

[Nereid]

An old-ish post, but still ...

My question is: If were seeing galaxies as they looked in the past. Could it be possible that were seeing our own galaxy too?

We could see our own galaxy-in-the-past, if there were some sort of giant mirror in the sky, reflecting the light from stars in the Milky Way back to us.

While I don't know of any such mirror, studying reflections of past events - that we, here on Earth, see 'today' - has been done (example), leading to conclusions about the nature of supernovae which would have been observed exploding centuries ago (had people here on Earth, at the right place, at the time been careful enough to observe the sky, and record what they saw).

[Beyond]

That was a pretty neat video of the reflection, Nereid. It brought to mind a song the Supremes sang about 'reflections'. From what i could make out from the video, It would seem that the supernovae and the reflection are about equal distance from here, and that we are getting the reflection from angled sides of what is doing the reflecting, not like if the reflecting surface was actually behind(farther away)the supernovae, in which case you could actually say the past is being reflected back to us. Of course i might have missed something.Which,alas,is all too common.

[Nereid]

That was a pretty neat video of the reflection, Nereid. It brought to mind a song the Supremes sang about 'reflections'. From what i could make out from the video, It would seem that the supernovae and the reflection are about equal distance from here, and that we are getting the reflection from angled sides of what is doing the reflecting, not like if the reflecting surface was actually behind(farther away)the supernovae, in which case you could actually say the past is being reflected back to us. Of course i might have missed something.Which,alas,is all too common.

Glad you liked it Beyond.

Your understanding is correct, in that the dust reflecting the supernova explosion is not behind the supernova, but off to one side. But it's not really a question of being behind vs off to one side; rather that what we see coming from the dust is light that has travelled further - ~400 light-years further - than the x-rays we see from the supernova remnant. If there were suitable clumps of dust ~200 light-years behind the position of the supernova (and just a fraction of a degree off-line), we'd see the same thing (ignoring any relative motion between the dust and the supernova (remnant)).

Also, the dust is not a mirror, so recovering any image from the reflected light would be exceedingly difficult; of course, careful time-lapse records would - or might - allow reconstruction of the light-curve of the supernova (i.e. how bright it was as a function of time), and taking spectra of the reflected light allows recovery of the spectrum of the supernova. Together these are enough to determine the type of supernova, and perhaps a few details of things like its pre-explosion mass.

[Beyond]

Thanks Nereid. Just looking at the picture, i forgot just how Big little bits are w-a-y out there. Gads, space is really BIG! Sure am glad i don't have to vacuum it.

[BMAONE23]

Thanks Nereid. Just looking at the picture, i forgot just how Big little bits are w-a-y out there. Gads, space is really BIG! Sure am glad i don't have to vacuum it.

Interestingly put Beyond...I always thought of Space as the place that vaccuums itself