Many sci-fi and fantasy fans enjoy stories about "time travelers" and some scientists try to research the principles behind such theoretical feats. What many people do not realize is that the Catholic Mass is an example of true "time travel."
Many Christians wish they could have "been there with Jesus," to know him and to talk to him when he lived and walked the earth. Jesus, as one of his last gifts, GAVE people the ability to do just that, generation after generation. Jesus gave the sacrament of the Holy Eucharist (also called Communion), celebrated during the Catholic Mass, so that people throughout the generations can literally and physically be present with him during his Last Supper, and join with him in giving sacrifice to God. When a person attends a Catholic Mass, he is literally taken back in time to be with Jesus during the Last Supper. Jesus explains this very clearly when he instructed the Apostles to "do this in memory of me."
What a strange choice of words for someone who had not "gone" anywhere! He is right there with them, yet tells them to perform the breaking of bread and sharing of wine "in memory" of him. Jesus is explaining that the Apostles are to continue to have a gathering of the Last Supper, and that he, Jesus, will be physically there with them, just as he is at that moment. This is what is meant by the Real Presence. Jesus is truly present in the Holy Eucharist.
I think people need to be reminded what a treasure and marvel that this is. When they ask, "Do we HAVE to go to Mass every week? *sigh*" my reply would be to explain, "Yes, for two reasons. One is that Jesus affirmed the validity of the Ten Commandments and one is that you shall keep the Lord's day holy. People used to keep the entire day holy. Now with shopping, TV, chores, work on Sunday and other activities, you should be glad to God that Mass fulfills the 'keeping the Sabbath holy' without taking the entire day. And second, do you not want to do what so many say they wish to do, which is to be with Jesus, know Jesus, and be physically in his presence and for him to literally be present in turn? Then why do not people run to Mass? It should be one of people's greatest desires, not a 'burden.'"
I hope this helps shed some light on the literal presence of Jesus Christ in the midst of everyone who takes the time to attend to him.