Serious question, how do you know if a profile is authentic in nostr?

nostr:npub1a2cww4kn9wqte4ry70vyfwqyqvpswksna27rtxd8vty6c74era8sdcw83a nostr:npub1s5yq6wadwrxde4lhfs56gn64hwzuhnfa6r9mj476r5s4hkunzgzqrs6q7z