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I want make a quick correction to the video on quasars.

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In that video I said and I mistakenly said that the quasars or that the accretion disk that's really forming

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or releasing the energy of the quasar, that its releasing energy predominately in the... the xray part of the electromagnetic spectrum.

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And that was incorrect. Most quasars are actually emitting electromagnetic radiation

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across the spectrum all the way from xrays... all the way from xrays as high frequency xrays all the way

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down to infrared. All the way down to infrared. And some quasars even release super high frequency gammarays

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and they will release low frequency electromagnetic waves all the way down to radio waves. So I just wanted

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to make that correction. Its not predominately in the x-ray part of the spectrum, its across the spectrum

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right over here. Its this entire range of the spectrum and sometimes even a wider range. Now the other

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thing I want to clarify is this is the range of the spectrum thats being emitted. But we have to remember

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that most or, actually all of these quasars are quite far away. The closest is 780 million light years away.

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And many of them are many many billions of light years away. And so they are moving away from us

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at a very fast speed, or... they are getting redshifted becuase the universe is expanding so fast relative

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to us at that point or that coordinate is moving so fast away from our coordinate. And so even though this is

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the spectrum that is beeing emitted its all going to be redshifted. Its all going to be redshifted

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down and so we are going to observe things at a much, at a much lower frequency-- maybe around the radio

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part of the frequency. So everything will be redshifted down. And thats why these were originally called

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Quasi stellar radio sources. Any hopefully that clears things up a little bit.