Defending from Tourism

I am playing a game as Poland on Emporer and I have a strong science lead, something like 6 techs over the next civ and I just hit the Atomic Era. I got Atomic Theory and now I am beelining straight for Rockets, and then Satellites.

What I am worried about is I only produce 20 culture / turn, and I have 20 happiness. I am third place in points and the two civs ahead of me are Arabia and Celts.

Do I have to worry about their tourism overcoming my culture and beating me once they reach the Atomic and Information Era? What is the best way to defend myself against Tourism if I am pure science? There's only 2 or 3 antiquity sites around me I can pick up and I have no culture guilds.

I suggest you check the influence by player tab in the culture screen and see how bad things are. At this point, you might need to wage war on the tourism leaders. In general, the defense against tourism is high culture and tourism of your own.

You should have 70+ tourism by Atomic. Did you slot arties/GWs?
If not then have all cities dig arties and musician bomb the cultural leader, or just flat-out exterminate him.

As has been said, to defend against tourism you really need to have high culture and tourism yourself. Not *too* high but more than 20. It's probably worth it to go for the guilds just for the extra culture. As for what you can do now, try to prevent as many modifiers as you can. Refuse their open borders in your lands. Try to get large military powers to DoW on them, both so they'll pillage trade routes they've established to you (thus reducing that modifier) and just slow them down in general. Or cut the middle man and DoW on them yourself. Getting The Great Firewall could also be useful.