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Asked by rohitmkiller to Adam, Geoff, Rob, Sheila, Suzie on 14 Mar 2011 in Categories: Space.
Question: There's a lot of research going on, trying to discover life in outer space via detection of radio waves and micro waves - although on our planet and in our lives, these 2 types of waves are quite fundamental, what is the guarantee that in a different galaxy, totally different physical laws may exist?
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Suzie Sheehy answered on 13 Mar 2011:
Good question!
There are a few different issues here – so I’ll try to go through them individually.
The first is the most fundamental, whether the laws of physics apply in different galaxies. They definitely do! (As far as we know) There is some evidence for this; if they didn’t, the galaxies wouldn’t be held together by gravity in the same way as ours and we probably wouldn’t see light from them in the same way no matter which galaxy we look at.
If we were to start talking about different Universes, though (rather than galaxies), it might be a totally different story! It often seems like our Universe was set up exactly so that life, as we know it, can exist. But what if gravity were different, or we had a whole different set of chemical elements, could life exist then? I’m sad to say we might never know, as even if alternative Universes do exist, we might never be able to access them.
The other issue here is whether radio or microwaves are signs of life. This is a great question – because although we broadcast signals out to space in these frequencies, what if other civilisations existed that broadcast in different frequencies? I assume the reason we choose these frequencies is because they travel very far in space without being stopped… (correct me if I’m wrong… I didn’t look that up!) so they might turn out to be sensible for other civilisations to use as well.
I think the bigger question you’ve raised, though, is whether we could ever be present in the Universe at the same time as an alien race? The Universe is 13.7 billion years old and in comparison the existence of humans is just a tiny flick of time, no longer than batting an eyelid. If that’s true, it might be that by the time we got a signal from aliens, who could be millions of light years away, they (or we) might no longer exist!
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Sheila Kanani answered on 13 Mar 2011:
Great question, you seem to know a lot about this already.
I asked a similar question to my supervisor when I was in Oz working with radio telescopes, trying to detect Earth mass planets orbiting pulsars.
The thing with science is that you can never guarantee anything at all. Everything in science can be altered or changed if we have enough evidence. For example, everyone believed in Newton’s gravity laws until Einstein came along and blew them out the water.
Most of science is based on theory, maths and assumptions. Especially in space science, because we can’t often test our theories (like we can’t actually go to a black hole to test what would happen if we fell into one, but we can model what would happen mathmatically).
So in all honesty, we don’t really know, and therefore can’t guarantee, anything!!
However, if you do believe in the Big Bang then you might also believe that everything in the universe evolved from one thing. That might mean that if there are radio waves in our galaxy then, because we evolved from the same thing, there should be radio waves in the next galaxy, and that physical laws that work for us should also work in this other galaxy. Does that make sense?
On the other hand, in terms of alien life, we may be using radio and micro waves to look for life in outer space but these outer space creatures might not be able to see or detect these waves back, so we still might not be able to discover them! -
Adam Tuff answered on 14 Mar 2011:
Great question! The short and sweet answer is, I don’t think there is any garantuee. We can use our physical laws and what we know about them, and use these to understand what we can observe from different galaxies, in the forms of light, radio and microwaves…and even high energy radiation like x-rays and gamma rays. We’re fairly sure the same laws of physics govern other galaxies, because we see a lot of what happens in our own galaxy going on in our neighbouring galaxy Andromeda. But as we look at galaxies further and further away, it’s harder to detect the faint radiation, and so we can be less sure about what goes on in them.
As far as detecting, or communicating with alien life using radiowaves goes, it is a long shot – who’s to say that aliens would use the same methods of communication? We just don’t know. CETI, a program set up many years ago, still monitors for signals that look like they are artificial (I.e. created by machinery) – they’ve found a few interesting things, but nothing that is anything close to proof. The search goes on!
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Geoff McBride answered on 14 Mar 2011:
I have read some papers on astromomers reporting the laws of physics being slightly different but it wasn’t significant but don’t forget some cosmologists say that the speed of light was slower in the past. It’s an exciting field of study at the moment. Some are even questioning ehether the big bang even happened.
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Robert Simpson answered on 14 Mar 2011:
We only have one example of how life works: planet Earth. when we look for organic life we look for water, because it seems on Earth that this is essential to life. When we look for communicating alien civilisations we again only have ourselves as an example.
Space is so big, and we have to start somewhere. If we are the only carbon-based, water-loving lifeforms in the universe and we are the only ones that use radio waves to communicate, then we’ll not find life with the way we’re looking at the moment. But we have to start from somewhere and it it works for us, then it might just work for someone else out there.
Comments
rohitmkiller commented on :
Okay, thank you for the answers so far – they have been enlightening!
So okay, I now understand that in fact there are lot of different factors which may or may not be due to the distances and limitations of space and in particular Universe exploration.
Suzie, you said that the Universe is 13.7 billion years old, and Sheila you said about how if I believe in the Big Bang theory, that the same physical laws must exist in all galaxies as they are in ours; however, what evidence is there that in fact the Big Bang that we have theorised is not the only one, but there were in fact other Big Bangs and more than 1 universe???
Adam commented on :
This is exactly the thoughts of those who believe in parallel universes that could exist on different dimensional planes – some have theorised that there could be infinite universes each with different properties…for example there might be one where gravity is a repulsive instead of an attractive force, and no planets, or life would ever form or exist! This would lead to an “omniverse” – a collection of universes with every possible set of laws of physics. Deep question!
Suzie commented on :
I don’t think there’s any hard evidence, as far as I know the multiple universe theory is just a theory at the moment 🙂
Sheila commented on :
I sometimes think of it as a glass of lemonade. You know the bubbles are going to appear and then pop, but you don’t know where or when. Imagine each of these bubbles is a big bang! This would mean in one glass of pop there are many universes and many big bangs.
So yes, there could be more than one big bang, and there could be more than one universe, but because we are in one, we have no idea what is going on elsewhere.
I like the idea of multiverses and being able to travel to parallel universes and seeing where I could end up, or what a parallel-me could be doing if I’d made different choices 🙂
rohitmkiller commented on :
Okay, thank you all for the answers – I’m beginning to understand exactly how diverse space is and as Robert and Adam, you’ve said how we only know about the physical laws in our galaxy and nearby galaxies but if the speed of light was slower in the past then surely even known physical laws are changing over broad lengths of time, therefore, as many other galaxies and stars are millions of light years away, we may never know anything different for the time it takes for the light or radio waves etc. to reach us.