Astronomers today are able to detect CMB radiation on earth using COBE satelites. Some of the CMB radiation detected from way back during the origin of space and time, just after The Big Bang almost 13.7 billion years ago. I mean that was way back in time, earth wasnt even born yet. How is it possible for radiation which was created 13.7 billion still be in existence today for human to detect and measure them ? On the same note, can astronomer / scientist detect light from let say 10 billion years ago ?
2007-02-01 03:28:29 · 8 answers · asked by chan_mun_keng 1 in Science & Mathematics ➔ Astronomy & Space
Because the cosmic microwave background is an artifact of the Big Bang. To be precise, it marks the moment the universe cooled enough for atomic nuclei to collect and hold on to the free electrons, converting the universe from an opaque highly-charged plasma to transparent neutral gas (meaning that, for the first time, instead of bouncing from particle to particle, photons could travel freely into into space.) As the universe wasn't very large at the time, this transition occured really quickly, and involved the entire universe. As a result, this flash of light would've come from everywhere, pretty much at once. That's an awful lot of photons. Though many would eventually collide with something and get absorbed, not all of them would suffer that fate, and continue to zip around the universe until their journey is cut short by being absorbed by a radio astronomer's microwave detector.
And yes, we could detect light from ten billion years ago. All we have to do is find an object ten billion light-years away. The light reaching us now from that particular object would have started on its journey ten billion years ago. In fact, we've found clusters of galaxies from ten billion years ago, and have glimpsed a galaxy from thirteen billion light-years away.
2007-02-01 04:07:49 · answer #1 · answered by Sam D 3 · 0⤊ 0⤋
the CMB is just a form of an electromagnetic wave, just like light. So as such it can only travel at the speed of light, so it still takes time to get to us from somewhere really far away. Same principle applies to everything we observe in distant space. For example, since Alpha Centauri (our nearest star BTW) is 25.8 trillion miles away, and light travels at 186,282.397 per second, if you do the math it will take the light roughly 1603 days, or 4.39 years, to reach us. So really when we look at our nearest star, we see what is happening 4.39 years ago there. When astronomers look out into space, we're looking into history. So to answer your question, the CMB radiation was emitted at a place that is 13.7 billion light years away, and since it can only travel at the speed of light, it has taken 13.7 billion years to get to us. All astronomers have to do to look at light from 10 billion years ago is to look at a galaxy thats 10 billion light years away. And it still exists, because all the CMB is is a much higher wavelength of visible light, and visible light travels forever too. photons can be asorbed or emitted by things, but not destroyed, so unless the radiation encouters some other factor that would cause it to be asorbed it will travel forever.
2007-02-01 04:03:31 · answer #2 · answered by Beach_Bum 4 · 0⤊ 0⤋
The leftover radiation from the big bang is EVERYWHERE. It was in that singularity that expanded, and it's filled space. The larger space gets (as the universe expands), the longer the wavelength gets - so it's cooling down, all the way to the microwave part of the spectrum. It's leftover radiation from 13.7 billion years ago, but it's everywhere, not just 13.7 billion light years away.
Yes, we can see light that left it's galaxy/star 10 billion years ago. Look up quasars, gamma ray bursts, and the Hubble deep field - these are galaxies, proto-galaxies, and extremely massive stars from the very first billion years or so of our galaxy. Pretty cool, huh?
2007-02-01 03:46:41 · answer #3 · answered by eri 7 · 0⤊ 0⤋
It's easy -- The radiation from the big bang has been traveling 13.7 billion years. The universe is transparent (since about 400,000 years after the big bang). Almost all the radiation has NOT hit a star, or even a stray atom, in all the time since then.
2007-02-01 03:56:56 · answer #4 · answered by morningfoxnorth 6 · 0⤊ 0⤋
Well, when you watch fireworks from a great distance away, you still hear the sounds from several seconds ago, even thought the explosive which created the sound is completely gone. It's the same thing with light waves. Just because the object which created them no longer exists, it doesn't mean that the light waves from its previous existence no longer exist. Got that?
And, yes, we can see light from 10 billion years ago.
2007-02-01 03:36:40 · answer #5 · answered by Anonymous · 1⤊ 0⤋
can you see a star ? well it could be that you are seeing that star 100000000 years ago ! because the speed of light is finite ! and only more or less 3*10^7 km/s, that means images of billions of years age are arriving only now.
The CMB is a little more complicated, because it's ubiquitous in every direction, but not uniform.
Just turn on the radio, go to a frequency without a radio station. you hear static. part of that static is CMB. welcome to radioastronomy.
2007-02-01 03:41:30 · answer #6 · answered by scientific_boy3434 5 · 0⤊ 0⤋
Beyond me pal.
2007-02-01 03:37:27 · answer #7 · answered by Anonymous · 0⤊ 4⤋
magic or alien technology
2007-02-01 03:35:34 · answer #8 · answered by Joel H 4 · 0⤊ 4⤋