5 ms·
This paper would seem to put many others estimating the prevalence of astrobiological activity into question.
by ipnon 6y ago
This paper would seem to put many others estimating the prevalence of astrobiological activity into question.
- ivalm 6y agoI don’t think so. For astrobiology we are mostly looking for life in our galaxy, this study looks at presence of very far away galaxies. For purposes of communication those galaxies are forever out of reach as they are at such high red shifts they are escaping from us faster than speed of light.
- ljlolel 6y ago"escaping from us faster than speed of light." ?????
- ksherlock 6y agohttps://en.wikipedia.org/wiki/Expansion_of_the_universe https://en.wikipedia.org/wiki/Expansion_of_the_universe The expansion of the universe is the increase in distance between any two given gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion whereby the scale of space itself changes. The universe does not expand "into" anything and does not require space to exist "outside" it. As the spatial part of the universe's spacetime metric increases in scale, objects move apart from one another at ever-increasing speeds. To any observer in the universe, it appears that all of space is expanding while all but the nearest galaxies recede at speeds that are proportional to their distance from the observer – at great enough distances the speeds exceed even the speed of light.
- drran 6y agoRed shift can be caused by Doppler shift of frequency and by loss of energy by photons. When Red shift is interpreted as 100% Doppler shift, then we have such absurd velocity. Of course, nobody saw a photonic boom when the whole galaxy crossed the speed of light barrier.
- ivalm 6y agoThat’s not at all what I/others are talking about. This is about expansion of the universe and new space being created between us and distant locations. Locally the galaxy isn’t moving particularly fast (relative to CMB, or whatever).