Exploring Intergalactic Bodies: What Information Do They Offer?

[zeromodz]

Is light the only type of information we get from intergalactic bodies? Is there any other type of information? Thank you

 

[Andy Resnick]

We also gain information from studying gravitational effects.

 

[Pengwuino]

What do you mean "information"? Most of our experiments look at the light produced, but there are experiments that look for things such as neutrinos.

Here's a link to one at the South Pole : http://icecube.wisc.edu/

 

[zeromodz]

I mean like is there any type of way for information to get from point a to b on intergalactic scales that doesn't involve light

 

[Nabeshin]

We also gain information from studying gravitational effects.

Yes, but you gain this information through analyzing the positions and motions of objects, all of which is received from light.

Neutrinos are a good alternative, and the other i can think of is gravitational wave astronomy, which of course is not really a branch of astronomy at all yet considering we haven't detected a single wave. Theoretically, though, it can offer a wealth of information.

 

[WannabeNewton]

you can also get information from gravitational waves although we have not been successful yet. Since gravitational waves interact much less with matter they contain a greater "wealth" of information than electromagnetic radiation.

 

[DaveC426913]

In case it does not go without saying: we receive information all up and down the electromagnetic spectrum, of which light is a teeny tiny wedge (less than one order of magnitude) sandwiched between about 10 orders of magnitude of radio & microwave on one side and about 6 orders of magnitude of x-rays & gamma rays on the other.

The radio spectrum is arguably far more rich in information about distant objects than light.

 

[Dr Lots-o'watts]

Light is only a small range the entire EM spectrum. Don't exclude radio, microwave, THz, IR, UV and x-ray and gamma. All of these need different kinds of telescopes.

There is a host of cosmic particles besides neutrinos.

Meteorites should not be neglected. And some probes have brought back dust from comet tails.

Gravitational waves may be detectable. Do a search for LIGO.

 

[DaveC426913]

Meteorites should not be neglected. And some probes have brought back dust from comet tails.

I think they can confidently be neglected considering the OP is asking about intergalactic information.

 

[pergradus]

don't forget cosmic rays, although I'm not sure exactly what information we can learn from them, they're still a source of "stuff" being sent our way.

 

[Dr Lots-o'watts]

Indeed. The title suggests "outer space", which has a broader definition.

 

[johng23]

Light is only a small range the entire EM spectrum. Don't exclude radio, microwave, THz, IR, UV and x-ray and gamma. All of these need different kinds of telescopes.

Are you of the opinion that the word "light" should only refer to visible light? It's definitely common to refer to infrared and UV light, and I've heard people (including myself) call x-rays and THz light as well. Otherwise the prefix "visible" would not be necessary.

Just wondering what most people's usage is.

 

[AstrophysicsX]

Don't forget sound waves.

 

[KingNothing]

Theoretically, anything at all can be considered "information". Perhaps all the bits and pieces of rocks that go through our atmosphere are encoded with some information. Anything that exists can technically be considered "information".

 

[russ_watters]

We don't get sound waves or bits of rock from intergalactic space!

 

[KingNothing]

We don't get bits of rock from intergalactic space!

Sure we do. What do you think meteorites are?

 

[russ_watters]

Sure we do. What do you think meteorites are?

Meteorites are bits of rock from our solar system, not from intergalactic space.

 

[Andy Resnick]

Yes, but you gain this information through analyzing the positions and motions of objects, all of which is received from light.

Neutrinos are a good alternative, and the other i can think of is gravitational wave astronomy, which of course is not really a branch of astronomy at all yet considering we haven't detected a single wave. Theoretically, though, it can offer a wealth of information.

The OP was rather vague: is the only *source* of information electromagnetic, or is the only mode of *transmission* of information electromagnetic?

 

[Andy Resnick]

In case it does not go without saying: we receive information all up and down the electromagnetic spectrum, of which light is a teeny tiny wedge (less than one order of magnitude) sandwiched between about 10 orders of magnitude of radio & microwave on one side and about 6 orders of magnitude of x-rays & gamma rays on the other.

Light is only a small range the entire EM spectrum.

To pic a nit, "light" refers to electromagnetic waves, and thus light covers the full spectrum- *visible* light occupies a vanishingly small fraction of the spectrum.

 

[DaveC426913]

To pic a nit, "light" refers to electromagnetic waves, and thus light covers the full spectrum- *visible* light occupies a vanishingly small fraction of the spectrum.

I beg to differ.

Light may refer to EM waves extending outside the visible portion, such as UV and IR, but light does not refer to radio waves.

 

[johng23]

I beg to differ.

Light may refer to EM waves extending outside the visible portion, such as UV and IR, but light does not refer to radio waves.

Ok, so what is the cut off? THz? Microwaves? And what is the physical reason for placing it where it is?

 

[DaveC426913]

Ok, so what is the cut off? THz? Microwaves? And what is the physical reason for placing it where it is?

I'd surmise it mostly has to do with the instruments we use to detect and manipulate them. If it can be manipulated with optical elements (glass), it's light. Radio waves and x-rays do not cooperate with telescopes made of glass elements.

 

[Andy Resnick]

I beg to differ.

Light may refer to EM waves extending outside the visible portion, such as UV and IR, but light does not refer to radio waves.

Why?

Back in the day, our millimeter-wave imaging system used lenses and waveguides. Any distinction is due to the tools used, not the physical concepts: diffraction, imaging, interference, etc apply to any frequency.

 

[DaveC426913]

Why?

Back in the day, our millimeter-wave imaging system used lenses and waveguides. Any distinction is due to the tools used, not the physical concepts: diffraction, imaging, interference, etc apply to any frequency.

It just seems kind of silly to talk about light when you're really talking about radio.

 

[SteamKing]

I don't think sound waves can be propagated thru outer space.

 

[DaveC426913]

I don't think sound waves can be propagated thru outer space.

Well, that's definitely true...

 

[JaWiB]

It just seems kind of silly to talk about light when you're really talking about radio.

It seems silly to talk about radio as a different thing when it's still an EM wave...


I think referring to other parts of the EM spectrum outside the visible as "not light" just confuses people. And by people I'm thinking of non-scientists.

 

[DaveC426913]

It seems silly to talk about radio as a different thing when it's still an EM wave...

As a different thing from what? EM? Sure. Light? No.

I think referring to other parts of the EM spectrum outside the visible as "not light" just confuses people. And by people I'm thinking of non-scientists.

Really? You don't think it confuses people if we start talking about the light being broadcast from a radio station?

Have you ever heard someone discuss the light emissions from a radio station, or the light emissions from a microwave oven?

 

[johng23]

Well, including microwave and radio in the category of "light" doesn't mean it has to become common usage to say you just warmed up your hot pocket with light. It just means that, when talking to a non-scientist about light, I may make a statement that "even radio waves are actually just light of a different wavelength".

Anyway, I see what you mean about detectors and optical elements being possible criteria for differentiating between light and "other" EM waves. But insisting that x-rays aren't light seems unacceptable. Most non-scientists only know of x-rays as the thing that takes pictures of your skeleton, and heck, the word "rays" is right in the name. If you're worried about confusing non-scientists I don't really think you're better off in this scenario.

 

[KingNothing]

Meteorites are bits of rock from our solar system, not from intergalactic space.

I guess I assumed that TS wasn't really trying to draw that distinction.

 

[turbo]

We get electromagnetic radiation (entire spectrum) from extragalactic space, as well as particles. Neutrinos and cosmic rays (some quite energetic) can originate from outside the MW, so we are not limited to "light" in that sense. One saving grace of observational astronomy is that it IS observational. All observers have the same data set to work with, apart from differences in the telescopes and detectors that they have access to.

 

[Dr Lots-o'watts]

Are you of the opinion that the word "light" should only refer to visible light?

Usually, I only use the word "light" if it's visible, but I suppose it can depend who I'm talking to and what's the context.

Thinking about it, in my daily work, we don't even use that word. It's just gamma, x-ray, UV, visible, IR (near, mid, far), THz, microwave and radio. All those are (EM) waves or beams.

Light refers to what happens when you flip the wall switch, and nothing on the optical bench.

As long as the message gets across, I guess.