Volcano explosions do not put out radioactive materials on the same scale.
Volcano explosions- the physical explosion is local- not widespread. Soot spreads- but there is a single centre of source.

In fact- there has been extinctions and population declines heavily linked with large volcano explosions due to climactic changes they can incur. So even though Volcanos are not weapons- they do kill.

Humanity has suffered two bottle necks in the past. Using DNA analysis it is estimated at one point our population dropped down below a couple-score. We very nearly went extinct.

We have enough nuclear material on this planet to destroy every urban centre. The radiation would spread in heavy doses to all areas. Climate change is likely- so even if radiation doesn't kill you- the fact that food supplies would be cut off would result in starvation. No water supply would be left un-altered. Survivors could be far-spread and not have interaction. Lower populations are more volatile and likely to die out due to random fluctuations.

What if all they showed on alien cable channels was reality show crap?

"Oh my Gawd, like this bimbo from Orion totally stabbed me in both of my backs. The Pegasus 457 bachelor was like, totally mine."

So, it's not all progress then.

It's not like world conquest or elimination of neighbours HASN'T been attempted before. It's not like it won't be attempted again (if we as a species live long enough).

Don't even need to be competing for resources to be a threat. It could be ideology, mental instability of leaders. Fear from the other side. Anything could drive them to war.

We'll probably be different enough that we can't trade. We'll certainly be different enough that we can't trade daughters in marriage agreements like nations of old did.

Yes, but we are advancing. Wouldn't it be safer to wipe us out BEFORE we're a threat- rather than risk waiting until we might be able to put up a fight?

I expect to see men on street corners around Denver holding signs:

"Will Poo for Food."

Quite sure. Not only that- but it was demonstrated in the 1940's in Japan. There are enough nuclear weapons to destroy the world many times over. We could wipe ourselves out if we chose.

Will help mine. I always took the "colonize like crazy" approach. By the time rival species are able to attack- you can afford to lose a few planets- and will be so far ahead of them by all other metrics you can quickly build a fleet to defeat them. More planets available makes this strategy even better.

Never played Moo3. But on Moo2- I found this strategy worked: declare war on the strongest enemy- do what it takes to get everyone else that you can to join in... you will get so much kudos for being in a mutal war- everyone will love you... you then take out the next biggest threat (getting everyone to join in)... then the next... then the next... and so on. If you get others to join in each time- your relationship with everyone will sky rocket meaning after the 2nd species you wipe out- you'll be able to get anyone you want to do whatever you want.

If they receive an I Love Lucy transmission- are able to determine it's purpose is TV entertainment- and figure out how to turn it into light/sound... ... we're all doomed- they'll send a death ray at us with immediate effect.

Or they have natural immunity via evolution. Species on earth have differing tolerances. Besides we can't expect alien life to use "DNA" unless populated via panspermia. It is possible their equivalent to our DNA (if they have one) is not affected by UV.

I'm sorry- but if you're going to use my poo to power your rickshaw- I expect to be paid for it. I worked long and hard producing that poo.

As cool as it would be to find another civilization- I hope we never do. At least- no one more advanced than us. (any one less advanced we probably would never find).

Chances of another civilization/species being friendly would be low. Think of it this way.

1) Anyone more advanced than us would likely have computers.
- if you have advanced computers- you would eventually rely on them for advice (at minimum) for running your government/civilization. We can therefore determine that their civilization would base decisions based on logic.

2) Logically- allowing another sapient species to exist would be a threat. There is always a possibility they will attack you, or compete for resources. The logical thing any sapient species should do to any other sapient species is wipe them out (if they can).

- you can always study a civilization from the ruins of their lands- after you exterminate them. We already have the technology to exterminate ourselves- so it is safe to assume any other more advanced species would too.

If the civilizations expired millions of years ago- and the planet is geologically active- there would probably be no trace.

If the civilization were more advanced than ours- we probably wouldn't know what to look for- and would probably never find them unless we landed there.

Nah... Sealand is smaller than the footprint required to launch a rocket. Also, at that latitude it would be more difficult than at the equator. They would need to aquire territory near the equator and with a military of two people- that might be tough.