The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
No wording about the date available; treat it as unverified.
Dr. Kaku's own site lays out the Kardashev scale and says of Type I status: "within 200 years or so, we should attain Type I status" - matching the pin's century-or-two estimate, though the page commits to no firm year, so it is the primary source for the idea rather than for 2100 specifically.[1]
Something missing or wrong? Say it in your own words: a link that backs this pin up, a different start or end date and why, or a fact it lacks or gets wrong. The AI checks it against this pin's sources, searches for better ones, and adds any page that backs you up. The pin's own sources still count most.