Ask your friends, “I want to know how much a liter of water weighs. Do you know the answer?”
Some of your friends will say, “It’s one kilogram. Someone I trust told me that once.”
Some will say, “I don’t know. And I don’t feel like weighing it.”
Some will not weigh it, don’t know the answer, but give you an incorrect answer anyway.
And a small number of your friends will actually get a scale and weigh it for you.
Those friends are called scientists. Cherish them.