How far the light can be shine?

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In summary: Otherwise, scientists use other methods like supernovae to estimate the age of the universe.Indirect methods. One way is to measure the redshift- how far a particular emission line has been skewed. The age of the universe is determined, in part, by the redshifted background radiation (the 4 K noise).Another way, as russ mentioned, is using "standard candles". These are sources that we "know" emit a certain amount of light: http://csep10.phys.utk.edu/astr162/lect/cosmology/cosmicd.html
  • #1
zyx_oay
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light can be speed faster about 300,000 km/s,
but how long the distance that light can be arrive?
 
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  • #2
You can see stars, can't you?
 
  • #3
Any distance until it interacts with something.
 
  • #4
We've observed objects as distant as about 13 billion light years. So, we know of light that has traveled that far. (For reference, 13 billion light years is a little more than 1.2*10^26 meters. That's 120 trillion trillion meters, which is about 75 billion trillion miles.)
 
  • #5
Parlyne said:
We've observed objects as distant as about 13 billion light years. So, we know of light that has traveled that far. (For reference, 13 billion light years is a little more than 1.2*10^26 meters. That's 120 trillion trillion meters, which is about 75 billion trillion miles.)

How do the scientists conclude that the particular light we received is x years old?
 
  • #6
light year rings...

i would imagine triangulation and knowing the speed of light would be an unrealistically simple way of doing it...
 
  • #8
Inertia still applies for EM radition, so i believe it depends entirely upon the environment into which you are shining the radiation. Since the majority of space is nearly a perfect vacuum EM radiation will countinue along its original vector until acted upon by an outside force ie... black hole, nebula, telescope ect. Someone please correct me if I am wrong.
 
  • #9
dst said:
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970415c.html


Doesn't sound all that precise to me, parallax aside?
Most of those methods are highly accurate, especially since stars tend to fit a very tight band of types.

Note, though, that those methods are used for stars in our galaxy. For more distant stars/galaxies, they use redshift, type 1a supernovas, and cephid variable stars (for really nearby galaxies).
 
  • #10
robertm said:
Inertia still applies for EM radition, so i believe it depends entirely upon the environment into which you are shining the radiation. Since the majority of space is nearly a perfect vacuum EM radiation will countinue along its original vector until acted upon by an outside force ie... black hole, nebula, telescope ect. Someone please correct me if I am wrong.
Inertia is a property of mass, so it doesn't apply to light, but otherwise yes, it is similar to Newton's first law - if nothing gets in the way, it'll keep going essentially forever. The Hubble has taken pictures of objects 13 billion light years away.

http://hubblesite.org/newscenter/archive/releases/1997/25
 
  • #11
russ_watters said:
Most of those methods are highly accurate, especially since stars tend to fit a very tight band of types.

Note, though, that those methods are used for stars in our galaxy. For more distant stars/galaxies, they use redshift, type 1a supernovas, and cephid variable stars (for really nearby galaxies).

Oh right, well I wouldn't know :grumpy:
 
  • #12
russ_watters said:
Most of those methods are highly accurate, especially since stars tend to fit a very tight band of types.

Note, though, that those methods are used for stars in our galaxy. For more distant stars/galaxies, they use redshift, type 1a supernovas, and cephid variable stars (for really nearby galaxies).

they use the supernovae as a reference because of how much light it emits, right?
 
  • #13
robertm said:
... black hole, nebula, telescope ect.
And eyeballs: if a photon manages to travel anything like a billion trillion miles I'd rather catch it with my eye than a ccd.
 
  • #14
jobyts said:
How do the scientists conclude that the particular light we received is x years old?

Indirect methods. One way is to measure the redshift- how far a particular emission line has been skewed. The age of the universe is determined, in part, by the redshifted background radiation (the 4 K noise).

Another way, as russ mentioned, is using "standard candles". These are sources that we "know" emit a certain amount of light:

http://csep10.phys.utk.edu/astr162/lect/cosmology/cosmicd.html

Parallax measurements are good only for very close objects.
 

1. How does light travel through space?

Light travels through space in the form of electromagnetic waves. These waves do not require a medium to travel through, unlike sound waves. This allows light to travel vast distances through the vacuum of space.

2. What is the speed of light?

The speed of light in a vacuum is approximately 299,792,458 meters per second, or about 670,616,629 miles per hour. This is the fastest speed at which anything can travel in our universe.

3. Can light travel forever?

While light can travel vast distances, it cannot travel forever. Eventually, it will either be absorbed by matter or scattered in different directions. However, the distance it can travel before this happens is incredibly far - billions of light years.

4. How far can we see with our eyes?

With our naked eyes, we can see objects that are up to 2.5 million light years away. This is because our eyes are only capable of detecting visible light, which is a small portion of the electromagnetic spectrum. However, with the use of telescopes and other technology, we can see objects that are much further away.

5. What is the furthest distance that light has been observed in the universe?

The furthest distance that light has been observed in the universe is approximately 13.4 billion light years away. This is the age of the universe, so anything beyond this distance is not visible to us because the light has not had enough time to reach us yet.

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