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As Hubble Breaks a Distance Record, We Learn Its True Limits
StartsWithABang writes: You might think that, when it comes to finding the most distant objects in the Universe, all we need is a good telescope, to leave the shutter open, and wait. As we accumulate more and more photons, we're bound to find the most distant, faint objects out there. Sure, Hubble just broke its own cosmic distance record, but it's certainly not the most distant. Thinking so misses an important fact: the Universe is expanding! And with that expansion, the wavelength of the light we can see gets redshifted. Ultraviolet light winds up in the infrared, infrared light winds up in the microwave, and the most distant galaxies that are out there are invisible, even to Hubble. Here are Hubble's limits, and how the James Webb Space Telescope will overcome them.
As often happens, my RSS feed display chopped off the end of the headline, and my overactive imagination supplied a much more interesting conclusion:
As Hubble Breaks a Distance Record, We Learn Its True ...
Purpose.
It's a radio... for talking to God!
systemd is Roko's Basilisk.
Because using capitals to indicate an exclaimation rather than an exclaimation point makes you look more intelligent?
What were you thinking, putting an autoplaying video on the front page????
(Sorry for going offtopic) ... or something.
Strange that video's never autoplay on my computer. Maybe you should install adblock+, ghostery, muter,
European Linux user, living in Antwerp
I guess you stumbled on a logical error (and you didn't read the article). 1. Very old light reaches us all the time, not just since the start of the Hubble. Thus light from very far away objects has hit Hubble from the beginning, but we weren't able yet to identify it. So there is a function of time, but it has more to do with our increasing ability to make sense of Hubble data. 2. The article talks mainly about the limits of Hubble. As it has a limited mirror area, the amount of light it can collect is limited. Objects farther away have to be brighter to be visible with Hubble. 3. Hubble works only with light that can be reflected by its mirror. The longest wavelength it can detect is 1 micron. As light that comes from far away is redshifted, its wavelength increases. Usually we use the Lyman series of absorbtion lines of Hydrogenium to measure the redshift. As soon as the shortest wavelength of the Lyman series is redshifted to a wavelength of more than 1 micron, we can't see it anymore in Hubble. Thus the farthest object of which we can estimate the distance with Hubble can't be farther away than the redshift of the Lyman series to 1 micron allows. Yes, also X ray can be redshifted to UV and to visible light, which then could be detected by Hubble, but we can't measure the redshift (yet), because we don't know how to identify the absorbtion lines that exists in X rays.
That's only if our telescopes could reach the Hubble Sphere. That way light speed + space expansion would be our distance limit and only time would allow us to see objects between the Hubble Sphere and the Cosmic Space Horizon.
But so far with our best equipment we are barely reaching a third of this distance and our limits are still of technological nature - or more accurately of economical nature (we *know* how to build better telescopes that would reach farther, but we don't have the budget).
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the distance to the visible horizon - the most distant object we can see - isn't growing, it's *shrinking*.
Not yet.
We have a much more firm limit in the form of the image of the Big Bang and it's still within the Hubble Sphere. We technically *could* see past it, but even if we had the hardware, it's pretty much opaque.
Yes, as the universe ages, the image moves away from us at c + expansion rate, and eventually it will vanish behind the cosmic event horizon forever, and since then its acceleration will begin to swallow objects making less available for observation. But we have a good few billion years until the cosmological limits imposed by space expansion become our worry. Until then, our theoretical limits are caused by the structure of the universe, and practical limits - by $$$.
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Note TFA has a redshift(z) scale that is backwards. They have z=1 at 6 billion years, and z>20 at 200 million years.
"an important fact: the Universe is expanding!" : Actually, this is not known, only theorized. It's based on the notion that red-shift / blue-shift relate to distance. But that's never been proven, and there are others out there that think it isn't about motion at all. Although we have a consensus opinion that uses it as fact, it isn't a proven fact.
What were you thinking, putting an autoplaying video on the front page????
(Sorry for going offtopic) Strange that video's never autoplay on my computer. Maybe you should install adblock+, ghostery, muter, ... or something.
Yes, because everyone reads slashdot on their infinitely customisable home computer, and not at work.
To have a right to do a thing is not at all the same as to be right in doing it
Then maybe you should promote these extensions to work's IT department as security tools, citing the use of Flash ads as drive-by Trojan droppers.
Maybe they should ask CSI for some help. Those guys have tech that can magnify any image to infinity.
We have already seen the point where the universe turns from an opaque plasma soup into transparent space. IIRC that's why the first cosmic background pics were called "the face of god".
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Please quit shooting all caps are worse than of what you are complaining, unless they have four in a row in which case fuck that guy there is never an excuse for four exclamation points
(briefly skims blogpost)
nope only one used at a time
---Saying gnome 3 is better than windows 8 not so much a compliment as it is damning with light praise.
Wow. Instead of StartsWithABang's usual EndsEveryOtherSentenceWithABang, it's down to EndsEveryThirdParagraphWithABang. Progress!
What's absorbing in the x-ray region? Certainly not hydrogen, taking a 1s to free would not absorb that much energy.