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/sci/ - Science & Math

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11305935 No.11305935 [Reply] [Original]

Hi,

so Ive read this because I too wondered why we can see farther than ~14 billion lightyears.
https://www.google.com/amp/s/www.forbes.com/sites/startswithabang/2018/02/23/if-the-universe-is-13-8-billion-years-old-how-can-we-see-46-billion-light-years-away/amp/
The 3-step solution explains it very good, by saying we can see the age of the universe x lightyears as a base. Then almost double that because the objects we see can move at almost lightspeed, so 13,8 x almost 2 = 27. Then he says the space itself between galaxies is expanding, pushing us to 41 billion lightyears, with an additional 5 billion because of dark energy. But it still leaves me with questions:

1) He says because the object we are seeing moves at almost lightspeed so we can calculate that the distance to it now is almost 2 times that of lightyears x age of universe. But why doesnt he include the option that the observer can too move at almost lightspeed away from the object hes seeing? Wouldnt that push us from 46 billion to 46 + 13,8 Billion lightyears?
2) Why can whole galaxies move at almost the speed of light? Because of dark energy again?
3) If the space between galaxies is expanding with more than the speed of light due to dark energy, why doesnt it go into two direction, doubling the speed? Like if I imagine the space between galaxies as 3d, wouldnt that mean it pushes the galaxies away at lightspeed+ and us away from the galaxies, again at lightspeed+, so 2x lightspeed+? Putting another 13,8 billions+ on the 46 billions + 13,8 billions.

>> No.11305938

>>11305935
forgot to edit an almost in
>Wouldnt that push us from 46 billion to 46 + (almost) 13,8 Billion lightyears?

>> No.11306001
File: 456 KB, 641x648, The Universe.png [View same] [iqdb] [saucenao] [google]
11306001

>>11305935
It is a wee bit more complex.

>> No.11306218 [DELETED] 

>>11305935
>the objects we see can move at almost lightspeed,
wrong
stuff st the edge of the observable universe, 46 bn ly away from us, is receding at about 3x c

>> No.11306224

>>11305935
>the objects we see can move at almost lightspeed,
wrong
stuff at the edge of the observable universe, 46 bn ly away from us, is receding at about 3x c

>> No.11306273

>>11306224
But is it receding due to its own speed or does it just appear/add up to that because of its own speed + the expanding Space + the speed of the observer?

>> No.11306391

>>11306273
>its own speed
not much of that going on, it's pretty much all because of space expansion. One exception is Andromeda, coming at us, but that's just a local quirk.

>> No.11306807

>>11306391
The site I quoted said only 13,8+5 of the 46 billion lightyears in radius is due to space extension. The rest is due to calculated place of objects that are moving away (redshift) and visible light simply due to lightyears times age of universe.

>> No.11306950

>>11306807
>site I quoted
too bad for the site

>> No.11306976
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11306976

>>11305935
>dark energy
the universe isn't expanding. it's a hoax by brainlets for brainlets.

>> No.11307208

>>11305935
>But why doesnt he include the option that the observer can too move at almost lightspeed away from the object hes seeing?
Galilean transformations for velocity are not applicable for relativistic speeds. Ignoring expansion, objects can never move away from you at more than c.

>> No.11308342

>>11307208
>>11307208
>Ignoring expansion, objects can never move away from you at more than c.

That's why I and the author of the site said almost