Can Babies See the Angels?
Question

Do children see the angels or the jinn?
If a nursing infant laughs when he is looking at an empty space in the room, does that mean that he has seen an angel?
Praise be to Allah.Is seeing the Angels possible?
Seeing the angels, in a form other than their true form in which Allah created them, is possible. It is proven that a number of the Companions saw the angels in human form , as was also proven among nations who came before us.
Can we see the Angles in their real form?
As for seeing the angels in their real form , there is no report regarding that except reports which say that the Prophet (blessings and peace of Allah be upon him) saw Jibril [in his real form] twice, and he was stunned by what he saw of his great size in his real form.
It was narrated that `Umar ibn Al-Khattab (may Allah be pleased with him) said: Whilst we were with the Messenger of Allah (blessings and peace of Allah be upon him) one day, a man came to us whose garment was exceedingly white and whose hair was exceedingly black, and there were no signs of travel on him, and none of us knew who he was. He came and sat before the Prophet (blessings and peace of Allah be upon him), resting his knees against his and placing his hands on his thighs. He said: O Muhammad, tell me about Islam…. And the Prophet (blessings and peace of Allah be upon him) said: “O `Umar, do you know who that questioner was?” I said: Allah and His Messenger know best. He said: “That was Jibril, who came to you to teach you your religion.” (Muslim, 8)
It was narrated that Sa`d ibn Abu Waqqas (may Allah be pleased with him) said: On the day of Uhud, I saw on the right of the Messenger of Allah (blessings and peace of Allah be upon him) and on his left two men wearing white garments, fighting fiercely to defend him, and I never saw them before or since. (Muslim, 2306) These two men were angels .
Al-Suyuti (may Allah have mercy on him) said: “Al-Nawawi said: From this Hadith, we understand that seeing the angels is not only for the prophets; rather the Companions and the Awliya’ (extremely pious people) have seen them, and they did not fight only on the day of Badr." (Sharh Al-Suyuti `ala Muslim 5/317)
Another example is Jibril (peace be upon him) appearing to Maryam (peace be upon her), and the Hadith about the angel who appeared to the bald man, the leper and the blind man, and other sound texts.
Can we see the Jinn?
Seeing the jinn – also in a form other than their real form – is also possible. Examples of that include the following:
It was narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) appointed me to guard the Ramadan zakah. Someone came and started taking some of the food. I grabbed hold of him and said, ‘I am going to take you to the Messenger of Allah (peace and blessings of Allah be upon him)!’ He said, ‘Let me be, for I am in need and I have children and am in great need.’ So I let him go. … At the end of the hadith it says: The Prophet (peace and blessings of Allah be upon him) said: `He indeed told you the truth, although he is a liar. Do you know who you have been speaking with for the past three nights, O Abu Hurayrah?’ I said, ‘No.’ He said, `That was a devil.’” (Muslim, 2187)
Ibn Hajar (may Allah have mercy on him) said: “What we learn from this Hadith… is that the devil may appear in different forms, so it is possible to see him. The words of Allah (interpretation of the meaning), {Indeed, he sees you, he and his tribe, from where you do not see them} [Al-A`raf 7:27] refer to when he is in his original form with which he was created." (Fat-h Al-Bari by Ibn Hajar  4/489)
Thus we know that seeing the angels and the jinn in a form other than their real form is possible and does happen.
Can babies see the Angels?
As for suggesting that only children can see that, we do not know of any text which speaks of that. This is a matter of the unseen, and we cannot say anything about it except on the basis of evidence, and there is no evidence to deny or affirm that.
And Allah knows best.