Use of and differences between "could be" and "could have been"

Question

Source

I was studying today's newspaper and this appeared:

How did the metals get there? Metals are used in practically every product we use. Even detergents and shampoos have traces of them. Nanoparticles are used to limit body odour in socks, for instance. A lot of this is absorbed by the body and discarded as waste, which enters the sewage system and treatment plants.

So I could have been a millionaire by now? Since the idea isn’t to sift through individual toilet refuse, no, you would still probably be where you are now. To actually mine the sewage, wastewater is treated through physical, biological, and chemical processes, resulting in treated water and biosolids. The biosolids, says US researchers, may be as good as a gold mine.

Is the usage of could have been correct? If yes, then how does it differ from I could be a millionaire by now?

Please explain this to me.

Answer 1

First of all, the difference between "could have been" and "could be" is that both of them indicate that it's impossible to get the result but why it's impossible is the difference, in could have been, it's impossible because it's past. It could have been possible if he did it in the past.

But with 'could be' it's impossible because it's unreal situation, it could have never happened in the past or now.. It's a hypothesis or imagination.

So here in your context the use of 'could have been' mean that it might have been possible that he becomes a millionaire if he started collecting that waste in the past.. It's real, not imaginary but it's impossible because it wasn't done in the past.

Answer 2

The simple answer is that both "could be" and "could have been" express some possibility or potential. "Could be" is used for potential future events:

If I invest in the right stock, I could be rich!

"Could have been" is used for potential past events, or ongoing events up to the present moment:

If I had invested in the right stocks back in the 1980's, I could have been rich by now.

In the context of the article, the writer is considering your point of view, and imagines you thinking about "mining" your excrement for precious minerals. She expresses it as a past potential because, in order to be rich today, you would have had to be mining for some time.

To put it another way: You imagine that, if you had started mining when you were 10, and today you're 40, then, by now, you could have been rich.

The key phrase here is "by now". This indicates the action continued up to the present moment. If you want to use "could be" in this context, just rephrase the sentence as a current possibility:

So (if I had been mining my excrement for some time) I could be a millionaire today?

Of course, as the article says: no, you neither (by now) would have been or (today) would be a millionaire, as there is only a very small amount of value in an individual's excrement.

Answer 3

Interesting question!

Could have been is correct here, and could be isn't, and I will show you why.

So I could have been a millionaire by now? is short for So I could have been a millionaire by now if my bodily waste had been harvested?

Another way of explaining: *So I could be a millionaire etc." isn't a conjecture, it isn't fantasy.

Answer 4

1. I could have been a millionaire by now... - but I won't be.

2. I could be a millionaire by now... - if I did it.

Plainly, when there is no possibility of getting any success we use 'could have been'.

When there is a possibility then 'could be' is used.

Consider:

1. I could have been a millionaire if I had accepted the deal. But unfortunately I did not accept the deal and I can not be a millionaire.

2. You could be a millionaire if you accept the deal. There is a chance for you to accept the deal and become a millionaire.