Thinking of investing in mechanical engineering companies

Software has been booming in developments in the past decade, to the point where we know that in the future it will replace 90% of all work done through computers, but we're still unsure of physical labor workers, theres always a deficit in that.
I firmly believe thats the future we've yet to see, if you ask most STEM students they'll tell you mechanical engineering will be the new hot field over compsci (im a compsci student myself).
Though I haven't seen any promising companies that do that, and I dont really understand economics enough.
What indexes or stocks are good for me to invest accourding to my beliefs? Im looking for a long term run.
Also feel free to dispute anything i've said if you dont agree, always looking to hear different opinions!