How can I argue that aliens/intelligent life does NOT exist anywhere else in the universe?

I am doing a debate for school and I cannot find information as to how aliens do NOT exist. If anyone has any ideas, scientific or not, that aliens do NOT exist, then I beg you. Or if you know where I could find this information. I don't want a debate here, just to find information please.
Thanks in advance!

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).